A Medley of Potpourri

Isotope	Abundance	Half-life (t_1/2)	Decay mode	Product
²⁰⁹At	syn	5.41 h	β⁺	²⁰⁹Po
²⁰⁹At	syn	5.41 h	α	²⁰⁵Bi
²¹⁰At	syn	8.1 h	β⁺	²¹⁰Po
²¹⁰At	syn	8.1 h	α	²⁰⁶Bi
²¹¹At	syn	7.21 h	ε	²¹¹Po
²¹¹At	syn	7.21 h	α	²⁰⁷Bi

Astatine is a chemical element with the symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements. All of astatine's isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours. A sample of the pure element has never been assembled, because any macroscopic specimen would be immediately vaporized by the heat of its own radioactivity.

The bulk properties of astatine are not known with certainty. Many of them have been estimated based on the element's position on the periodic table as a heavier analog of iodine, and a member of the halogens (the group of elements including fluorine, chlorine, bromine, and iodine). However, astatine also falls roughly along the dividing line between metals and nonmetals, and some metallic behavior has also been observed and predicted for it. Astatine is likely to have a dark or lustrous appearance and may be a semiconductor or possibly a metal. Chemically, several anionic species of astatine are known and most of its compounds resemble those of iodine, but it also sometimes displays metallic characteristics and shows some similarities to silver.

The first synthesis of the element was in 1940 by Dale R. Corson, Kenneth Ross MacKenzie, and Emilio G. Segrè at the University of California, Berkeley, who named it from the Ancient Greek ἄστατος (astatos) 'unstable'. Four isotopes of astatine were subsequently found to be naturally occurring, although much less than one gram is present at any given time in the Earth's crust. Neither the most stable isotope astatine-210, nor the medically useful astatine-211, occur naturally; they can only be produced synthetically, usually by bombarding bismuth-209 with alpha particles.

Characteristics

Astatine is an extremely radioactive element; all its isotopes have half-lives of 8.1 hours or less, decaying into other astatine isotopes, bismuth, polonium, or radon. Most of its isotopes are very unstable, with half-lives of one second or less. Of the first 101 elements in the periodic table, only francium is less stable, and all the astatine isotopes more stable than francium are in any case synthetic and do not occur in nature.

The bulk properties of astatine are not known with any certainty. Research is limited by its short half-life, which prevents the creation of weighable quantities. A visible piece of astatine would immediately vaporize itself because of the heat generated by its intense radioactivity. It remains to be seen if, with sufficient cooling, a macroscopic quantity of astatine could be deposited as a thin film. Astatine is usually classified as either a nonmetal or a metalloid; metal formation has also been predicted.

Physical

Most of the physical properties of astatine have been estimated (by interpolation or extrapolation), using theoretically or empirically derived methods. For example, halogens get darker with increasing atomic weight – fluorine is nearly colorless, chlorine is yellow green, bromine is red brown, and iodine is dark gray/violet. Astatine is sometimes described as probably being a black solid (assuming it follows this trend), or as having a metallic appearance (if it is a metalloid or a metal).

Astatine sublimes less readily than does iodine, having a lower vapor pressure. Even so, half of a given quantity of astatine will vaporize in approximately an hour if put on a clean glass surface at room temperature. The absorption spectrum of astatine in the middle ultraviolet region has lines at 224.401 and 216.225 nm, suggestive of 6p to 7s transitions.

The structure of solid astatine is unknown. As an analogue of iodine it may have an orthorhombic crystalline structure composed of diatomic astatine molecules, and be a semiconductor (with a band gap of 0.7 eV). Alternatively, if condensed astatine forms a metallic phase, as has been predicted, it may have a monatomic face-centered cubic structure; in this structure it may well be a superconductor, like the similar high-pressure phase of iodine. Evidence for (or against) the existence of diatomic astatine (At₂) is sparse and inconclusive. Some sources state that it does not exist, or at least has never been observed, while other sources assert or imply its existence. Despite this controversy, many properties of diatomic astatine have been predicted; for example, its bond length would be 300±10 pm, dissociation energy 83.7±12.5 kJ/mol, and heat of vaporization (∆H_vap) 54.39 kJ/mol. Many values have been predicted for the melting and boiling points of astatine, but only for At₂.

Chemical

The chemistry of astatine is "clouded by the extremely low concentrations at which astatine experiments have been conducted, and the possibility of reactions with impurities, walls and filters, or radioactivity by-products, and other unwanted nano-scale interactions". Many of its apparent chemical properties have been observed using tracer studies on extremely dilute astatine solutions, typically less than 10⁻¹⁰ mol·L⁻¹. Some properties, such as anion formation, align with other halogens. Astatine has some metallic characteristics as well, such as plating onto a cathode, and coprecipitating with metal sulfides in hydrochloric acid. It forms complexes with EDTA, a metal chelating agent, and is capable of acting as a metal in antibody radiolabeling; in some respects astatine in the +1 state is akin to silver in the same state. Most of the organic chemistry of astatine is, however, analogous to that of iodine. It has been suggested that astatine can form a stable monatomic cation in aqueous solution, but electromigration evidence suggests that the cationic At(I) species is protonated hypoastatous acid (H₂OAt⁺), showing analogy to iodine.

Astatine has an electronegativity of 2.2 on the revised Pauling scale – lower than that of iodine (2.66) and the same as hydrogen. In hydrogen astatide (HAt), the negative charge is predicted to be on the hydrogen atom, implying that this compound could be referred to as astatine hydride according to certain nomenclatures. That would be consistent with the electronegativity of astatine on the Allred–Rochow scale (1.9) being less than that of hydrogen (2.2). However, official IUPAC stoichiometric nomenclature is based on an idealized convention of determining the relative electronegativities of the elements by the mere virtue of their position within the periodic table. According to this convention, astatine is handled as though it is more electronegative than hydrogen, irrespective of its true electronegativity. The electron affinity of astatine, at 233 kJ mol⁻¹, is 21% less than that of iodine. In comparison, the value of Cl (349) is 6.4% higher than F (328); Br (325) is 6.9% less than Cl; and I (295) is 9.2% less than Br. The marked reduction for At was predicted as being due to spin–orbit interactions. The first ionisation energy of astatine is about 899 kJ mol⁻¹, which continues the trend of decreasing first ionisation energies down the halogen group (fluorine, 1681; chlorine, 1251; bromine, 1140; iodine, 1008).

Compounds

Less reactive than iodine, astatine is the least reactive of the halogens. Its compounds have been synthesized in nano-scale amounts and studied as intensively as possible before their radioactive disintegration. The reactions involved have been typically tested with dilute solutions of astatine mixed with larger amounts of iodine. Acting as a carrier, the iodine ensures there is sufficient material for laboratory techniques (such as filtration and precipitation) to work. Like iodine, astatine has been shown to adopt odd-numbered oxidation states ranging from −1 to +7.

Only a few compounds with metals have been reported, in the form of astatides of sodium, palladium, silver, thallium, and lead. Some characteristic properties of silver and sodium astatide, and the other hypothetical alkali and alkaline earth astatides, have been estimated by extrapolation from other metal halides.

Hydrogen astatide space-filling model

The formation of an astatine compound with hydrogen – usually referred to as hydrogen astatide – was noted by the pioneers of astatine chemistry. As mentioned, there are grounds for instead referring to this compound as astatine hydride. It is easily oxidized; acidification by dilute nitric acid gives the At⁰ or At⁺ forms, and the subsequent addition of silver(I) may only partially, at best, precipitate astatine as silver(I) astatide (AgAt). Iodine, in contrast, is not oxidized, and precipitates readily as silver(I) iodide.

Astatine is known to bind to boron, carbon, and nitrogen. Various boron cage compounds have been prepared with At–B bonds, these being more stable than At–C bonds. Astatine can replace a hydrogen atom in benzene to form astatobenzene C₆H₅At; this may be oxidized to C₆H₅AtCl₂ by chlorine. By treating this compound with an alkaline solution of hypochlorite, C₆H₅AtO₂ can be produced. The dipyridine-astatine(I) cation, [At(C₅H₅N)₂]⁺, forms ionic compounds with perchlorate (a non-coordinating anion) and with nitrate, [At(C₅H₅N)₂]NO₃. This cation exists as a coordination complex in which two dative covalent bonds separately link the astatine(I) centre with each of the pyridine rings via their nitrogen atoms.

With oxygen, there is evidence of the species AtO⁻ and AtO⁺ in aqueous solution, formed by the reaction of astatine with an oxidant such as elemental bromine or (in the last case) by sodium persulfate in a solution of perchloric acid: the latter species might also be protonated astatous acid, H
₂AtO⁺
₂. The species previously thought to be AtO⁻
₂ has since been determined to be AtO(OH)⁻
₂, a hydrolysis product of AtO⁺ (another such hydrolysis product being AtOOH). The well characterized AtO⁻
₃ anion can be obtained by, for example, the oxidation of astatine with potassium hypochlorite in a solution of potassium hydroxide. Preparation of lanthanum triastatate La(AtO₃)₃, following the oxidation of astatine by a hot Na₂S₂O₈ solution, has been reported. Further oxidation of AtO⁻
₃, such as by xenon difluoride (in a hot alkaline solution) or periodate (in a neutral or alkaline solution), yields the perastatate ion AtO⁻
₄; this is only stable in neutral or alkaline solutions. Astatine is also thought to be capable of forming cations in salts with oxyanions such as iodate or dichromate; this is based on the observation that, in acidic solutions, monovalent or intermediate positive states of astatine coprecipitate with the insoluble salts of metal cations such as silver(I) iodate or thallium(I) dichromate.

Astatine may form bonds to the other chalcogens; these include S₇At⁺ and At(CSN)⁻
₂ with sulfur, a coordination selenourea compound with selenium, and an astatine–tellurium colloid with tellurium.

Structure of astatine monoiodide, one of the astatine interhalogens and the heaviest known diatomic interhalogen.

Astatine is known to react with its lighter homologs iodine, bromine, and chlorine in the vapor state; these reactions produce diatomic interhalogen compounds with formulas AtI, AtBr, and AtCl. The first two compounds may also be produced in water – astatine reacts with iodine/iodide solution to form AtI, whereas AtBr requires (aside from astatine) an iodine/iodine monobromide/bromide solution. The excess of iodides or bromides may lead to AtBr⁻
₂ and AtI⁻
₂ ions, or in a chloride solution, they may produce species like AtCl⁻
₂ or AtBrCl⁻
via equilibrium reactions with the chlorides. Oxidation of the element with dichromate (in nitric acid solution) showed that adding chloride turned the astatine into a molecule likely to be either AtCl or AtOCl. Similarly, AtOCl⁻
₂ or AtCl⁻
₂ may be produced. The polyhalides PdAtI₂, CsAtI₂, TlAtI₂, and PbAtI are known or presumed to have been precipitated. In a plasma ion source mass spectrometer, the ions [AtI]⁺, [AtBr]⁺, and [AtCl]⁺ have been formed by introducing lighter halogen vapors into a helium-filled cell containing astatine, supporting the existence of stable neutral molecules in the plasma ion state. No astatine fluorides have been discovered yet. Their absence has been speculatively attributed to the extreme reactivity of such compounds, including the reaction of an initially formed fluoride with the walls of the glass container to form a non-volatile product. Thus, although the synthesis of an astatine fluoride is thought to be possible, it may require a liquid halogen fluoride solvent, as has already been used for the characterization of radon fluoride.

History

Dmitri Mendeleev's table of 1871, with an empty space at the eka-iodine position

In 1869, when Dmitri Mendeleev published his periodic table, the space under iodine was empty; after Niels Bohr established the physical basis of the classification of chemical elements, it was suggested that the fifth halogen belonged there. Before its officially recognized discovery, it was called "eka-iodine" (from Sanskrit eka – "one") to imply it was one space under iodine (in the same manner as eka-silicon, eka-boron, and others). Scientists tried to find it in nature; given its extreme rarity, these attempts resulted in several false discoveries.

The first claimed discovery of eka-iodine was made by Fred Allison and his associates at the Alabama Polytechnic Institute (now Auburn University) in 1931. The discoverers named element 85 "alabamine", and assigned it the symbol Ab, designations that were used for a few years. In 1934, H. G. MacPherson of University of California, Berkeley disproved Allison's method and the validity of his discovery. There was another claim in 1937, by the chemist Rajendralal De. Working in Dacca in British India (now Dhaka in Bangladesh), he chose the name "dakin" for element 85, which he claimed to have isolated as the thorium series equivalent of radium F (polonium-210) in the radium series. The properties he reported for dakin do not correspond to those of astatine; moreover, astatine is not found in the thorium series, and the true identity of dakin is not known.

In 1936, the team of Romanian physicist Horia Hulubei and French physicist Yvette Cauchois claimed to have discovered element 85 via X-ray analysis. In 1939, they published another paper which supported and extended previous data. In 1944, Hulubei published a summary of data he had obtained up to that time, claiming it was supported by the work of other researchers. He chose the name "dor", presumably from the Romanian for "longing" [for peace], as World War II had started five years earlier. As Hulubei was writing in French, a language which does not accommodate the "ine" suffix, dor would likely have been rendered in English as "dorine", had it been adopted. In 1947, Hulubei's claim was effectively rejected by the Austrian chemist Friedrich Paneth, who would later chair the IUPAC committee responsible for recognition of new elements. Even though Hulubei's samples did contain astatine, his means to detect it were too weak, by current standards, to enable correct identification. He had also been involved in an earlier false claim as to the discovery of element 87 (francium) and this is thought to have caused other researchers to downplay his work.

A greyscale photo of the upper body of a man

Emilio Segrè, one of the discoverers of the main-group element astatine

In 1940, the Swiss chemist Walter Minder announced the discovery of element 85 as the beta decay product of radium A (polonium-218), choosing the name "helvetium" (from Helvetia, the Latin name of Switzerland). Berta Karlik and Traude Bernert were unsuccessful in reproducing his experiments, and subsequently attributed Minder's results to contamination of his radon stream (radon-222 is the parent isotope of polonium-218). In 1942, Minder, in collaboration with the English scientist Alice Leigh-Smith, announced the discovery of another isotope of element 85, presumed to be the product of thorium A (polonium-216) beta decay. They named this substance "anglo-helvetium", but Karlik and Bernert were again unable to reproduce these results.

Later in 1940, Dale R. Corson, Kenneth Ross MacKenzie, and Emilio Segrè isolated the element at the University of California, Berkeley. Instead of searching for the element in nature, the scientists created it by bombarding bismuth-209 with alpha particles in a cyclotron (particle accelerator) to produce, after emission of two neutrons, astatine-211. The discoverers, however, did not immediately suggest a name for the element. The reason for this was that at the time, an element created synthetically in "invisible quantities" that had not yet been discovered in nature was not seen as a completely valid one; in addition, chemists were reluctant to recognize radioactive isotopes as legitimately as stable ones. In 1943, astatine was found as a product of two naturally occurring decay chains by Berta Karlik and Traude Bernert, first in the so-called uranium series, and then in the actinium series. (Since then, astatine was also found in a third decay chain, the neptunium series.) Friedrich Paneth in 1946 called to finally recognize synthetic elements, quoting, among other reasons, recent confirmation of their natural occurrence, and proposed that the discoverers of the newly discovered unnamed elements name these elements. In early 1947, Nature published the discoverers' suggestions; a letter from Corson, MacKenzie, and Segrè suggested the name "astatine" coming from the Greek astatos (αστατος) meaning "unstable", because of its propensity for radioactive decay, with the ending "-ine", found in the names of the four previously discovered halogens. The name was also chosen to continue the tradition of the four stable halogens, where the name referred to a property of the element.

Corson and his colleagues classified astatine as a metal on the basis of its analytical chemistry. Subsequent investigators reported iodine-like, cationic, or amphoteric behavior. In a 2003 retrospective, Corson wrote that "some of the properties [of astatine] are similar to iodine … it also exhibits metallic properties, more like its metallic neighbors Po and Bi."

Isotopes

Alpha decay characteristics for sample astatine isotopes
Mass number	Mass excess	Half-life	Probability of alpha decay	Alpha decay half-life
207	−13.243 MeV	1.80 h	8.6%	20.9 h
208	−12.491 MeV	1.63 h	0.55%	12.3 d
209	−12.880 MeV	5.41 h	4.1%	5.5 d
210	−11.972 MeV	8.1 h	0.175%	193 d
211	−11.647 MeV	7.21 h	41.8%	17.2 h
212	−8.621 MeV	0.31 s	≈100%	0.31 s
213	−6.579 MeV	125 ns	100%	125 ns
214	−3.380 MeV	558 ns	100%	558 ns
219	10.397 MeV	56 s	97%	58 s
220	14.350 MeV	3.71 min	8%	46.4 min
221	16.810 MeV	2.3 min	experimentally alpha stable	∞

There are 39 known isotopes of astatine, with atomic masses (mass numbers) of 191–229. Theoretical modeling suggests that 37 more isotopes could exist. No stable or long-lived astatine isotope has been observed, nor is one expected to exist.

Astatine's alpha decay energies follow the same trend as for other heavy elements. Lighter astatine isotopes have quite high energies of alpha decay, which become lower as the nuclei become heavier. Astatine-211 has a significantly higher energy than the previous isotope, because it has a nucleus with 126 neutrons, and 126 is a magic number corresponding to a filled neutron shell. Despite having a similar half-life to the previous isotope (8.1 hours for astatine-210 and 7.2 hours for astatine-211), the alpha decay probability is much higher for the latter: 41.81% against only 0.18%. The two following isotopes release even more energy, with astatine-213 releasing the most energy. For this reason, it is the shortest-lived astatine isotope. Even though heavier astatine isotopes release less energy, no long-lived astatine isotope exists, because of the increasing role of beta decay (electron emission). This decay mode is especially important for astatine; as early as 1950 it was postulated that all isotopes of the element undergo beta decay, though nuclear mass measurements indicate that ²¹⁵At is in fact beta-stable, as it has the lowest mass of all isobars with A = 215. A beta decay mode has been found for all other astatine isotopes except for astatine-213, astatine-214, and astatine-216m. Astatine-210 and lighter isotopes exhibit beta plus decay (positron emission), astatine-216 and heavier isotopes exhibit beta minus decay, and astatine-212 decays via both modes, while astatine-211 undergoes electron capture.

The most stable isotope is astatine-210, which has a half-life of 8.1 hours. The primary decay mode is beta plus, to the relatively long-lived (in comparison to astatine isotopes) alpha emitter polonium-210. In total, only five isotopes have half-lives exceeding one hour (astatine-207 to -211). The least stable ground state isotope is astatine-213, with a half-life of 125 nanoseconds. It undergoes alpha decay to the extremely long-lived bismuth-209.

Astatine has 24 known nuclear isomers, which are nuclei with one or more nucleons (protons or neutrons) in an excited state. A nuclear isomer may also be called a "meta-state", meaning the system has more internal energy than the "ground state" (the state with the lowest possible internal energy), making the former likely to decay into the latter. There may be more than one isomer for each isotope. The most stable of these nuclear isomers is astatine-202m1, which has a half-life of about 3 minutes, longer than those of all the ground states bar those of isotopes 203–211 and 220. The least stable is astatine-214m1; its half-life of 265 nanoseconds is shorter than those of all ground states except that of astatine-213.

Natural occurrence

Neptunium series, showing the decay products, including astatine-217, formed from neptunium-237

Astatine is the rarest naturally occurring element. The total amount of astatine in the Earth's crust (quoted mass 2.36 × 10²⁵ grams) is estimated by some to be less than one gram at any given time.^[6] Other sources estimate the amount of ephemeral astatine, present on earth at any given moment, to be up to one ounce (about 28 grams).

Any astatine present at the formation of the Earth has long since disappeared; the four naturally occurring isotopes (astatine-215, -217, -218 and -219) are instead continuously produced as a result of the decay of radioactive thorium and uranium ores, and trace quantities of neptunium-237. The landmass of North and South America combined, to a depth of 16 kilometers (10 miles), contains only about one trillion astatine-215 atoms at any given time (around 3.5 × 10⁻¹⁰ grams). Astatine-217 is produced via the radioactive decay of neptunium-237. Primordial remnants of the latter isotope—due to its relatively short half-life of 2.14 million years—are no longer present on Earth. However, trace amounts occur naturally as a product of transmutation reactions in uranium ores. Astatine-218 was the first astatine isotope discovered in nature. Astatine-219, with a half-life of 56 seconds, is the longest lived of the naturally occurring isotopes.

Isotopes of astatine are sometimes not listed as naturally occurring because of misconceptions that there are no such isotopes, or discrepancies in the literature. Astatine-216 has been counted as a naturally occurring isotope but reports of its observation (which were described as doubtful) have not been confirmed.

Synthesis

Formation

Possible reactions after bombarding bismuth-209 with alpha particles
Reaction	Energy of alpha particle
²⁰⁹ ₈₃Bi + ⁴ ₂He → ²¹¹ ₈₅At + 2 ¹ ₀n	26 MeV
²⁰⁹ ₈₃Bi + ⁴ ₂He → ²¹⁰ ₈₅At + 3 ¹ ₀n	40 MeV
²⁰⁹ ₈₃Bi + ⁴ ₂He → ²⁰⁹ ₈₅At + 4 ¹ ₀n	60 MeV

Astatine was first produced by bombarding bismuth-209 with energetic alpha particles, and this is still the major route used to create the relatively long-lived isotopes astatine-209 through astatine-211. Astatine is only produced in minuscule quantities, with modern techniques allowing production runs of up to 6.6 giga becquerels (about 86 nanograms or 2.47 × 10¹⁴ atoms). Synthesis of greater quantities of astatine using this method is constrained by the limited availability of suitable cyclotrons and the prospect of melting the target. Solvent radiolysis due to the cumulative effect of astatine decay is a related problem. With cryogenic technology, microgram quantities of astatine might be able to be generated via proton irradiation of thorium or uranium to yield radon-211, in turn decaying to astatine-211. Contamination with astatine-210 is expected to be a drawback of this method.

The most important isotope is astatine-211, the only one in commercial use. To produce the bismuth target, the metal is sputtered onto a gold, copper, or aluminium surface at 50 to 100 milligrams per square centimeter. Bismuth oxide can be used instead; this is forcibly fused with a copper plate. The target is kept under a chemically neutral nitrogen atmosphere, and is cooled with water to prevent premature astatine vaporization. In a particle accelerator, such as a cyclotron, alpha particles are collided with the bismuth. Even though only one bismuth isotope is used (bismuth-209), the reaction may occur in three possible ways, producing astatine-209, astatine-210, or astatine-211. In order to eliminate undesired nuclides, the maximum energy of the particle accelerator is set to a value (optimally 29.17 MeV) above that for the reaction producing astatine-211 (to produce the desired isotope) and below the one producing astatine-210 (to avoid producing other astatine isotopes).

Separation methods

Since astatine is the main product of the synthesis, after its formation it must only be separated from the target and any significant contaminants. Several methods are available, "but they generally follow one of two approaches—dry distillation or [wet] acid treatment of the target followed by solvent extraction." The methods summarized below are modern adaptations of older procedures, as reviewed by Kugler and Keller. Pre-1985 techniques more often addressed the elimination of co-produced toxic polonium; this requirement is now mitigated by capping the energy of the cyclotron irradiation beam.

Dry

The astatine-containing cyclotron target is heated to a temperature of around 650 °C. The astatine volatilizes and is condensed in (typically) a cold trap. Higher temperatures of up to around 850 °C may increase the yield, at the risk of bismuth contamination from concurrent volatilization. Redistilling the condensate may be required to minimize the presence of bismuth (as bismuth can interfere with astatine labeling reactions). The astatine is recovered from the trap using one or more low concentration solvents such as sodium hydroxide, methanol or chloroform. Astatine yields of up to around 80% may be achieved. Dry separation is the method most commonly used to produce a chemically useful form of astatine.

Wet

The irradiated bismuth (or sometimes bismuth trioxide) target is first dissolved in, for example, concentrated nitric or perchloric acid. Following this first step, the acid can be distilled away to leave behind a white residue that contains both bismuth and the desired astatine product. This residue is then dissolved in a concentrated acid, such as hydrochloric acid. Astatine is extracted from this acid using an organic solvent such as butyl or isopropyl ether, diisopropylether (DIPE), or thiosemicarbazide. Using liquid-liquid extraction, the astatine product can be repeatedly washed with an acid, such as HCl, and extracted into the organic solvent layer. A separation yield of 93% using nitric acid has been reported, falling to 72% by the time purification procedures were completed (distillation of nitric acid, purging residual nitrogen oxides, and redissolving bismuth nitrate to enable liquid–liquid extraction). Wet methods involve "multiple radioactivity handling steps" and have not been considered well suited for isolating larger quantities of astatine. However, wet extraction methods are being examined for use in production of larger quantities of astatine-211, as it is thought that wet extraction methods can provide more consistency. They can enable the production of astatine in a specific oxidation state and may have greater applicability in experimental radiochemistry.

Uses and precautions

Several ²¹¹At-containing molecules and their experimental uses
Agent	Applications
[²¹¹At]astatine-tellurium colloids	Compartmental tumors
6-[²¹¹At]astato-2-methyl-1,4-naphtaquinol diphosphate	Adenocarcinomas
²¹¹At-labeled methylene blue	Melanomas
Meta-[²¹¹At]astatobenzyl guanidine	Neuroendocrine tumors
5-[²¹¹At]astato-2'-deoxyuridine	Various
²¹¹At-labeled biotin conjugates	Various pretargeting
²¹¹At-labeled octreotide	Somatostatin receptor
²¹¹At-labeled monoclonal antibodies and fragments	Various
²¹¹At-labeled bisphosphonates	Bone metastases

Newly formed astatine-211 is the subject of ongoing research in nuclear medicine. It must be used quickly as it decays with a half-life of 7.2 hours; this is long enough to permit multistep labeling strategies. Astatine-211 has potential for targeted alpha-particle therapy, since it decays either via emission of an alpha particle (to bismuth-207), or via electron capture (to an extremely short-lived nuclide, polonium-211, which undergoes further alpha decay), very quickly reaching its stable granddaughter lead-207. Polonium X-rays emitted as a result of the electron capture branch, in the range of 77–92 keV, enable the tracking of astatine in animals and patients. Although astatine-210 has a slightly longer half-life, it is wholly unsuitable because it usually undergoes beta plus decay to the extremely toxic polonium-210.

The principal medicinal difference between astatine-211 and iodine-131 (a radioactive iodine isotope also used in medicine) is that iodine-131 emits high-energy beta particles, and astatine does not. Beta particles have much greater penetrating power through tissues than do the much heavier alpha particles. An average alpha particle released by astatine-211 can travel up to 70 µm through surrounding tissues; an average-energy beta particle emitted by iodine-131 can travel nearly 30 times as far, to about 2 mm. The short half-life and limited penetrating power of alpha radiation through tissues offers advantages in situations where the "tumor burden is low and/or malignant cell populations are located in close proximity to essential normal tissues." Significant morbidity in cell culture models of human cancers has been achieved with from one to ten astatine-211 atoms bound per cell.

Astatine ... [is] miserable to make and hell to work with.

P Durbin, Human Radiation Studies: Remembering the Early Years, 1995

Several obstacles have been encountered in the development of astatine-based radiopharmaceuticals for cancer treatment. World War II delayed research for close to a decade. Results of early experiments indicated that a cancer-selective carrier would need to be developed and it was not until the 1970s that monoclonal antibodies became available for this purpose. Unlike iodine, astatine shows a tendency to dehalogenate from molecular carriers such as these, particularly at sp³ carbon sites (less so from sp² sites). Given the toxicity of astatine accumulated and retained in the body, this emphasized the need to ensure it remained attached to its host molecule. While astatine carriers that are slowly metabolized can be assessed for their efficacy, more rapidly metabolized carriers remain a significant obstacle to the evaluation of astatine in nuclear medicine. Mitigating the effects of astatine-induced radiolysis of labeling chemistry and carrier molecules is another area requiring further development. A practical application for astatine as a cancer treatment would potentially be suitable for a "staggering" number of patients; production of astatine in the quantities that would be required remains an issue.

Animal studies show that astatine, similarly to iodine – although to a lesser extent, perhaps because of its slightly more metallic nature – is preferentially (and dangerously) concentrated in the thyroid gland. Unlike iodine, astatine also shows a tendency to be taken up by the lungs and spleen, possibly because of in-body oxidation of At^– to At⁺. If administered in the form of a radiocolloid it tends to concentrate in the liver. Experiments in rats and monkeys suggest that astatine-211 causes much greater damage to the thyroid gland than does iodine-131, with repetitive injection of the nuclide resulting in necrosis and cell dysplasia within the gland. Early research suggested that injection of astatine into female rodents caused morphological changes in breast tissue; this conclusion remained controversial for many years. General agreement was later reached that this was likely caused by the effect of breast tissue irradiation combined with hormonal changes due to irradiation of the ovaries. Trace amounts of astatine can be handled safely in fume hoods if they are well-aerated; biological uptake of the element must be avoided.

Perspectivism

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Perspectivism

Part of a series on
Epistemology
Category Index Outline
Core concepts Belief Justification Knowledge Truth
Distinctions A priori vs. A posteriori Analytic vs. synthetic
Schools of thought Empiricism Naturalism Pragmatism Rationalism Relativism Skepticism
Topics and views Certainty Coherentism Contextualism Dogmatism Experience Fallibilism Foundationalism Induction Infallibilism Infinitism Perspectivism Rationality Reason Solipsism
Specialized domains of inquiry Applied epistemology Evolutionary epistemology Feminist epistemology Formal epistemology Metaepistemology Social epistemology
Notable epistemologists Aristotle Sextus Empiricus Edmund Gettier René Descartes David Hume Immanuel Kant W. V. O. Quine more...
Related fields Epistemic logic Philosophy of mind Philosophy of perception Philosophy of science Probability

Core concepts

Distinctions

Schools of thought

Topics and views

Specialized domains of inquiry

Notable epistemologists

Related fields

Perspectivism (German: Perspektivismus; also called perspectivalism) is the epistemological principle that perception of and knowledge of something are always bound to the interpretive perspectives of those observing it. While perspectivism does not regard all perspectives and interpretations as being of equal truth or value, it holds that no one has access to an absolute view of the world cut off from perspective. Instead, all such viewing occurs from some point of view which in turn affects how things are perceived. Rather than attempt to determine truth by correspondence to things outside any perspective, perspectivism thus generally seeks to determine truth by comparing and evaluating perspectives among themselves. Perspectivism may be regarded as an early form of epistemological pluralism, though in some accounts includes treatment of value theory, moral psychology, and realist metaphysics.

Early forms of perspectivism have been identified in the philosophies of Protagoras, Michel de Montaigne, and Gottfried Leibniz. However, its first major statement is considered to be Friedrich Nietzsche's development of the concept in the 19th century, having built off Gustav Teichmüller's use of the term some years prior. For Nietzsche, perspectivism takes the form of a realist antimetaphysics while rejecting both the correspondence theory of truth and the notion that the truth-value of a belief always constitutes its ultimate worth-value. The perspectival conception of objectivity used by Nietzsche sees the deficiencies of each perspective as remediable by an asymptotic study of the differences between them. This stands in contrast to Platonic notions in which objective truth is seen to reside in a wholly non-perspectival domain. Despite this, perspectivism is often misinterpreted as a form of relativism or as a rejection of objectivity entirely. Though it is often mistaken to imply that no way of seeing the world can be taken as definitively true, perspectivism can instead be interpreted as holding certain interpretations (such as that of perspectivism itself) to be definitively true.

During the 21st century, perspectivism has led a number of developments within analytic philosophy and philosophy of science, particularly under the early influence of Ronald Giere, Jay Rosenberg, Ernest Sosa, and others. This contemporary form of perspectivism, also known as scientific perspectivism, is more narrowly focused than prior forms—centering on the perspectival limitations of scientific models, theories, observations, and focused interest, while remaining more compatible for example with Kantian philosophy and correspondence theories of truth. Furthermore, scientific perspecitivism has come to address a number of scientific fields such as physics, biology, cognitive neuroscience, and medicine, as well as interdisciplinarity and philosophy of time. Studies of perspectivism have also been introduced into contemporary anthropology, initially through the influence of Eduardo Viveiros de Castro and his research into indigenous cultures of South America.

The basic principle that things are perceived differently from different perspectives (or that perspective determines one's limited and unprivileged access to knowledge) has sometimes been accounted as a rudimentary, uncontentious form of perspectivism. The basic practice of comparing contradictory perspectives to one another may also be considered one such form of perspectivism (See also: Intersubjectivity), as may the entire philosophical problem of how true knowledge is to penetrate one's perspectival limitations.

Precursors and early developments

In Western languages, scholars have found perspectivism in the philosophies of Heraclitus (c. 540 – c. 480 BCE), Protagoras (c. 490 – c. 420 BCE), Michel de Montaigne (1533 – 1592 CE), and Gottfried Leibniz (1646 – 1716 CE). The origins of perspectivism have also been found to lie also within Renaissance developments in philosophy of art and its artistic notion of perspective. In Asian languages, scholars have found perspectivism in Buddhist, Jain, and Daoist texts. Anthropologists have found a kind of perspectivism in the thinking of some indigenous peoples.

Ancient Greek philosophy

The Western origins of perspectivism can be found in the pre-Socratic philosophies of Heraclitus and Protagoras. In fact, a major cornerstone of Plato's philosophy is his rejection and opposition to perspectivism—this forming a principal element of his aesthetics, ethics, epistemology, and theology. The antiperspectivism of Plato made him a central target of critique for later perspectival philosophers such as Nietzsche.

Montaigne

Montaigne's philosophy presents in itself a perspectivism less as a doctrinaire position than as a core philosophical approach put into practice. Inasmuch as no one can occupy a God's-eye view, Montaigne holds that no one has access to a view which is totally unbiased, which does not interpret according to its own perspective. It is instead only the underlying psychological biases which view one's own perspective as unbiased. In a passage from his "Of Cannibals", he writes:

Men of intelligence notice more things and view them more carefully, but they [interpret] them; and to establish and substantiate their interpretation, they cannot refrain from altering the facts a little. They never present things just as they are but twist and disguise them to conform to the point of view from which they have seen them; and to gain credence for their opinion and make it attractive, they do not mind adding something of their own, or extending and amplifying.
— Michel de Montaigne, "Of Cannibals", Essais (1595), trans. J. M. Cohen

Nietzsche

In his works, Nietzsche makes a number of statements on perspective which at times contrast each other throughout the development of his philosophy. Nietzsche's perspectivism begins by challenging the underlying notions of 'viewing from nowhere', 'viewing from everywhere', and 'viewing without interpreting' as being absurdities. Instead, all viewing is attached to some perspective, and all viewers are limited in some sense to the perspectives at their command. In The Genealogy of Morals he writes:

Let us be on guard against the dangerous old conceptual fiction that posited a 'pure, will-less, painless, timeless knowing subject'; let us guard against the snares of such contradictory concepts as 'pure reason', 'absolute spirituality', 'knowledge in itself': these always demand that we should think of an eye that is completely unthinkable, an eye turned in no particular direction, in which the active and interpreting forces, through which alone seeing becomes seeing something, are supposed to be lacking; these always demand of the eye an absurdity and a nonsense. There is only a perspective seeing, only a perspective knowing; and the more affects we allow to speak about one thing, the more eyes, different eyes, we can use to observe one thing, the more complete will our 'concept' of this thing, our 'objectivity' be.
— Friedrich Nietzsche, The Genealogy of Morals (1887; III:12), transl. Walter Kaufmann

In this, Nietzsche takes a contextualist approach which rejects any God's-eye view of the world. This has been further linked to his notion of the death of God and the dangers of a resulting relativism. However, Nietzsche's perspectivism itself stands in sharp contrast to any such relativism. In outlining his perspectivism, Nietzsche rejects those who claim everything to be subjective, by disassembling the notion of the subject as itself a mere invention and interpretation. He further states that, since the two are mutually dependent on each other, the collapse of the God's-eye view causes also the notion of the thing-in-itself to fall apart with it. Nietzsche views this collapse to reveal, through his genealogical project, that all that has been considered non-perspectival knowledge, the entire tradition of Western metaphysics, has itself been only a perspective. His perspectivism and genealogical project are further integrated into each other in addressing the psychological drives that underlie various philosophical programs and perspectives, as a form of critique. Here, contemporary scholar Ken Gemes views Nietzsche's perspectivism to above all be a principle of moral psychology, rejecting interpretations of it as an epistemological thesis outrightly. It is through this method of critique that the deficiencies of various perspectives can be alleviated—through a critical mediation of the differences between them rather than any appeals to the non-perspectival. In a posthumously published aphorism from The Will to Power, Nietzsche writes:

"Everything is subjective," you say; but even this is interpretation. The "subject" is not something given, it is something added and invented and projected behind what there is.—Finally, is it necessary to posit an interpreter behind the interpretation? Even this is invention, hypothesis.
In so far as the word "knowledge" has any meaning, the world is knowable; but it is interpretable otherwise, it has no meaning behind it, but countless meanings.—"Perspectivism."
It is our needs that interpret the world; our drives and their For and Against. Every drive is a kind of lust to rule; each one has its perspective that it would like to compel all the other drives to accept as a norm.
— Friedrich Nietzsche, The Will to Power, §481 (1883–1888), transl. Walter Kaufmann and R. J. Hollingdale

While Nietzsche does not plainly reject truth and objectivity, he does reject the notions of absolute truth, external facts, and non-perspectival objectivity.

Truth theory and the value of truth

Despite receiving much attention within contemporary philosophy, there is no academic consensus on Nietzsche's conception of truth. While his perspectivism presents a number of challenges regarding the nature of truth, its more controversial element lies in its questioning of the value of truth. Contemporary scholars Steven D. Hales and Robert C. Welshon write that:

Nietzsche's writings on truth are among the most elusive and difficult ones in his corpus. One indication of their obscurity is that on an initial reading he appears either blatantly inconsistent in his use of the words 'true' and 'truth', or subject to inexplicable vacillations on the value of truth.

Later developments

In the 20th century, perspectivism was discussed separately by José Ortega y Gasset and Karl Jaspers.

Ortega

Ortega's perspectivism, replaced his previous position that "man is completely social". His reversal is prominent in his work Verdad y perspectiva ("Truth and perspective"), where he explained that "each man has a mission of truth" and that what he sees of reality no other eye sees. He explained:

From different positions two people see the same surroundings. However, they do not see the same thing. Their different positions mean that the surroundings are organized in a different way: what is in the foreground for one may be in the background for another. Furthermore, as things are hidden one behind another, each person will see something that the other may not.

Ortega also maintained that perspective is perfected by the multiplication of its viewpoints. He noted that war transpires due to the lack of perspective and failure to see the larger contexts of the actions among nations. Ortega also cited the importance of phenomenology in perspectivism as he argued against speculation and the importance of concrete evidence in understanding truth and reality. In this discourse, he highlighted the role of "circumstance" in finding out the truth since it allows us to understand realities beyond ourselves.

Varieties

Contemporary varieties of perspectivism include:

Structuration theory

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Structuration_theory

The theory of structuration is a social theory of the creation and reproduction of social systems that is based on the analysis of both structure and agents (see structure and agency), without giving primacy to either. Furthermore, in structuration theory, neither micro- nor macro-focused analysis alone is sufficient. The theory was proposed by sociologist Anthony Giddens, most significantly in The Constitution of Society, which examines phenomenology, hermeneutics, and social practices at the inseparable intersection of structures and agents. Its proponents have adopted and expanded this balanced position. Though the theory has received much criticism, it remains a pillar of contemporary sociological theory.

Premises and origins

Sociologist Anthony Giddens adopted a post-empiricist frame for his theory, as he was concerned with the abstract characteristics of social relations. This leaves each level more accessible to analysis via the ontologies which constitute the human social experience: space and time ("and thus, in one sense, 'history'.") His aim was to build a broad social theory which viewed "[t]he basic domain of study of the social sciences... [as] neither the experience of the individual actor, nor the existence of any form of societal totality, but social practices ordered across space and time." His focus on abstract ontology accompanied a general and purposeful neglect of epistemology or detailed research methodology.

Giddens used concepts from objectivist and subjectivist social theories, discarding objectivism's focus on detached structures, which lacked regard for humanist elements and subjectivism's exclusive attention to individual or group agency without consideration for socio-structural context. He critically engaged classical nineteenth and early twentieth century social theorists such as Auguste Comte, Karl Marx, Max Weber, Émile Durkheim, Alfred Schutz, Robert K. Merton, Erving Goffman, and Jürgen Habermas. Thus, in many ways, structuration was "an exercise in clarification of logical issues." Structuration drew on other fields, as well: "He also wanted to bring in from other disciplines novel aspects of ontology that he felt had been neglected by social theorists working in the domains that most interested him. Thus, for example, he enlisted the aid of geographers, historians and philosophers in bringing notions of time and space into the central heartlands of social theory." Giddens hoped that a subject-wide "coming together" might occur which would involve greater cross-disciplinary dialogue and cooperation, especially between anthropologists, social scientists and sociologists of all types, historians, geographers, and even novelists. Believing that "literary style matters", he held that social scientists are communicators who share frames of meaning across cultural contexts through their work by utilising "the same sources of description (mutual knowledge) as novelists or others who write fictional accounts of social life."

Structuration differs from its historical sources. Unlike structuralism it sees the reproduction of social systems not "as a mechanical outcome, [but] rather ... as an active constituting process, accomplished by, and consisting in, the doings of active subjects." Unlike Althusser's concept of agents as "bearers" of structures, structuration theory sees them as active participants. Unlike the philosophy of action and other forms of interpretative sociology, structuration focuses on structure rather than production exclusively. Unlike Saussure's production of an utterance, structuration sees language as a tool from which to view society, not as the constitution of society—parting with structural linguists such as Claude Lévi-Strauss and generative grammar theorists such as Noam Chomsky. Unlike post-structuralist theory, which put similar focus on the effects of time and space, structuration does not recognise only movement, change and transition. Unlike functionalism, in which structures and their virtual synonyms, "systems", comprise organisations, structuration sees structures and systems as separate concepts. Unlike Marxism, structuration avoids an overly restrictive concept of "society" and Marxism's reliance on a universal "motor of history" (i.e. class conflict), its theories of societal "adaptation", and its insistence on the working class as universal class and socialism as the ultimate form of modern society. Finally, "structuration theory cannot be expected to furnish the moral guarantees that critical theorists sometimes purport to offer."

Main ideas

Duality of structure

Giddens observed that in social analysis, the term structure referred generally to "rules and resources" and more specifically to "the structuring properties allowing the 'binding' of time-space in social systems". These properties make it possible for similar social practices to exist across time and space and that lend them "systemic" form. Agents—groups or individuals—draw upon these structures to perform social actions through embedded memory, called memory traces. Memory traces are thus the vehicle through which social actions are carried out. Structure is also, however, the result of these social practices. Thus, Giddens conceives of the duality of structure as being:

...the essential recursiveness of social life, as constituted in social practices: structure is both medium and outcome of reproduction of practices. Structure enters simultaneously into the constitution of the agent and social practices, and 'exists' in the generating moments of this constitution.

Giddens uses "the duality of structure" (i.e. material/ideational, micro/macro) to emphasize structure's nature as both medium and outcome. Structures exist both internally within agents as memory traces that are the product of phenomenological and hermeneutic inheritance and externally as the manifestation of social actions. Similarly, social structures contain agents and/or are the product of past actions of agents. Giddens holds this duality, alongside "structure" and "system," in addition to the concept of recursiveness, as the core of structuration theory. His theory has been adopted by those with structuralist inclinations, but who wish to situate such structures in human practice rather than to reify them as an ideal type or material property. (This is different, for example, from actor–network theory which appears to grant a certain autonomy to technical artifacts.)

Social systems have patterns of social relation that change over time; the changing nature of space and time determines the interaction of social relations and therefore structure. Hitherto, social structures or models were either taken to be beyond the realm of human control—the positivistic approach—or posit that action creates them—the interpretivist approach. The duality of structure emphasizes that they are different sides to the same central question of how social order is created.

Gregor McLennan suggested renaming this process "the duality of structure and agency", since both aspects are involved in using and producing social actions.

Cycle of structuration

The duality of structure is essentially a feedback–feedforward process whereby agents and structures mutually enact social systems, and social systems in turn become part of that duality. Structuration thus recognizes a social cycle. In examining social systems, structuration theory examines structure, modality, and interaction. The "modality" (discussed below) of a structural system is the means by which structures are translated into actions.

Interaction

Interaction is the agent's activity within the social system, space and time. "It can be understood as the fitful yet routinized occurrence of encounters, fading away in time and space, yet constantly reconstituted within different areas of time-space." Rules can affect interaction, as originally suggested by Goffman. "Frames" are "clusters of rules which help to constitute and regulate activities, defining them as activities of a certain sort and as subject to a given range of sanctions." Frames are necessary for agents to feel "ontological security, the trust that everyday actions have some degree of predictability. Whenever individuals interact in a specific context they address—without any difficulty and in many cases without conscious acknowledgement—the question: "What is going on here?" Framing is the practice by which agents make sense of what they are doing.

Routinization

Structuration theory is centrally concerned with order as "the transcending of time and space in human social relationships". Institutionalized action and routinization are foundational in the establishment of social order and the reproduction of social systems. Routine persists in society, even during social and political revolutions, where daily life is greatly deformed, "as Bettelheim demonstrates so well, routines, including those of an obnoxious sort, are re-established." Routine interactions become institutionalized features of social systems via tradition, custom and/or habit, but this is no easy societal task and it "is a major error to suppose that these phenomena need no explanation. On the contrary, as Goffman (together with ethnomethodology) has helped to demonstrate, the routinized character of most social activity is something that has to be 'worked at' continually by those who sustain it in their day-to-day conduct." Therefore, routinized social practices do not stem from coincidence, "but the skilled accomplishments of knowledgeable agents."

Trust and tact are essential for the existence of a "basic security system, the sustaining (in praxis) of a sense of ontological security, and [thus] the routine nature of social reproduction which agents skilfully organize. The monitoring of the body, the control and use of face in 'face work'—these are fundamental to social integration in time and space."

Explanation

When I utter a sentence I draw upon various syntactical rules (sedimented in my practical consciousness of the language) in order to do so. These structural features of the language are the medium whereby I generate the utterance. But in producing a syntactically correct utterance I simultaneously contribute to the reproduction of the language as a whole. ...The relation between moment and totality for social theory... [involves] a dialectic of presence and absence which ties the most minor or trivial forms of social action to structural properties of the overall society, and to the coalescence of institutions over long stretches of historical time.

Thus, even the smallest social actions contribute to the alteration or reproduction of social systems. Social stability and order is not permanent; agents always possess a dialectic of control (discussed below) which allows them to break away from normative actions. Depending on the social factors present, agents may cause shifts in social structure.

The cycle of structuration is not a defined sequence; it is rarely a direct succession of causal events. Structures and agents are both internal and external to each other, mingling, interrupting, and continually changing each other as feedbacks and feedforwards occur. Giddens stated, "The degree of "systemness" is very variable. ...I take it to be one of the main features of structuration theory that the extension and 'closure' of societies across space and time is regarded as problematic."

The use of "patriot" in political speech reflects this mingling, borrowing from and contributing to nationalistic norms and supports structures such as a police state, from which it in turn gains impact.

Structure and society

Structures are the "rules and resources" embedded in agents' memory traces. Agents call upon their memory traces of which they are "knowledgeable" to perform social actions. "Knowledgeability" refers to "what agents know about what they do, and why they do it." Giddens divides memory traces (structures-within-knowledgeability) into three types:

Domination (power): Giddens also uses "resources" to refer to this type. "Authoritative resources" allow agents to control persons, whereas "allocative resources" allow agents to control material objects.
Signification (meaning): Giddens suggests that meaning is inferred through structures. Agents use existing experience to infer meaning. For example, the meaning of living with mental illness comes from contextualized experiences.
Legitimation (norms): Giddens sometimes uses "rules" to refer to either signification or legitimation. An agent draws upon these stocks of knowledge via memory to inform him or herself about the external context, conditions, and potential results of an action.

When an agent uses these structures for social interactions, they are called modalities and present themselves in the forms of facility (domination), interpretive scheme/communication (signification) and norms/sanctions (legitimation).

Thus, he distinguishes between overall "structures-within-knowledgeability" and the more limited and task-specific "modalities" on which these agents subsequently draw when they interact.

The duality of structures means that structures enter "simultaneously into the constitution of the agent and social practices, and 'exists' in the generating moments of this constitution." "Structures exist paradigmatically, as an absent set of differences, temporally "present" only in their instantiation, in the constituting moments of social systems." Giddens draws upon structuralism and post-structuralism in theorizing that structures and their meaning are understood by their differences.

Agents and society

Giddens' agents follow previous psychoanalysis work done by Sigmund Freud and others. Agency, as Giddens calls it, is human action. To be human is to be an agent (not all agents are human). Agency is critical to both the reproduction and the transformation of society. Another way to explain this concept is by what Giddens calls the "reflexive monitoring of actions." "Reflexive monitoring" refers to agents' ability to monitor their actions and those actions' settings and contexts. Monitoring is an essential characteristic of agency. Agents subsequently "rationalize," or evaluate, the success of those efforts. All humans engage in this process, and expect the same from others. Through action, agents produce structures; through reflexive monitoring and rationalization, they transform them. To act, agents must be motivated, must be knowledgeable must be able to rationalize the action; and must reflexively monitor the action.

Agents, while bounded in structure, draw upon their knowledge of that structural context when they act. However, actions are constrained by agents' inherent capabilities and their understandings of available actions and external limitations. Practical consciousness and discursive consciousness inform these abilities. Practical consciousness is the knowledgeability that an agent brings to the tasks required by everyday life, which is so integrated as to be hardly noticed. Reflexive monitoring occurs at the level of practical consciousness. Discursive consciousness is the ability to verbally express knowledge. Alongside practical and discursive consciousness, Giddens recognizes actors as having reflexive, contextual knowledge, and that habitual, widespread use of knowledgeability makes structures become institutionalized.

Agents rationalize, and in doing so, link the agent and the agent's knowledgeability. Agents must coordinate ongoing projects, goals, and contexts while performing actions. This coordination is called reflexive monitoring and is connected to ethnomethodology's emphasis on agents' intrinsic sense of accountability.

The factors that can enable or constrain an agent, as well as how an agent uses structures, are known as capability constraints include age, cognitive/physical limits on performing multiple tasks at once and the physical impossibility of being in multiple places at once, available time and the relationship between movement in space and movement in time.

Location offers are a particular type of capability constraint. Examples include:

Locale
Regionalization: political or geographical zones, or rooms in a building
Presence: Do other actors participate in the action? (see co-presence); and more specifically
Physical presence: Are other actors physically nearby?

Agents are always able to engage in a dialectic of control, able to "intervene in the world or to refrain from such intervention, with the effect of influencing a specific process or state of affairs." In essence, agents experience inherent and contrasting amounts of autonomy and dependence; agents can always either act or not.

Methodology

Structuration theory is relevant to research, but does not prescribe a methodology and its use in research has been problematic. Giddens intended his theory to be abstract and theoretical, informing the hermeneutic aspects of research rather than guiding practice. Giddens wrote that structuration theory "establishes the internal logical coherence of concepts within a theoretical network."^[2]^: 34 Giddens criticized many researchers who used structuration theory for empirical research, critiquing their "en bloc" use of the theory's abstract concepts in a burdensome way. "The works applying concepts from the logical framework of structuration theory that Giddens approved of were those that used them more selectively, 'in a spare and critical fashion.'" Giddens and followers used structuration theory more as "a sensitizing device".

Structuration theory allows researchers to focus on any structure or concept individually or in combination. In this way, structuration theory prioritizes ontology over epistemology. In his own work, Giddens focuses on production and reproduction of social practices in some context. He looked for stasis and change, agent expectations, relative degrees of routine, tradition, behavior, and creative, skillful, and strategic thought simultaneously. He examined spatial organization, intended and unintended consequences, skilled and knowledgeable agents, discursive and tacit knowledge, dialectic of control, actions with motivational content, and constraints. Structuration theorists conduct analytical research of social relations, rather than organically discovering them, since they use structuration theory to reveal specific research questions, though that technique has been criticized as cherry-picking.

Giddens preferred strategic conduct analysis, which focuses on contextually situated actions. It employs detailed accounts of agents' knowledgeability, motivation, and the dialectic of control.

Criticisms and additions

Though structuration theory has received critical expansion since its origination, Giddens' concepts remained pivotal for later extension of the theory, especially the duality of structure.

Strong structuration

Rob Stones argued that many aspects of Gidden's original theory had little place in its modern manifestation. Stones focused on clarifying its scope, reconfiguring some concepts and inserting new ones, and refining methodology and research orientations. Strong structuration:

Places its ontology more in situ than abstractly.
Introduces the quadripartite cycle, which details the elements in the duality of structure. These are:
- external structures as conditions of action;
- internal structures within the agent;
- active agency, "including a range of aspects involved when agents draw upon internal structures in producing practical action"; and
- outcomes (as both structures and events).
Increases attention to epistemology and methodology. Ontology supports epistemology and methodology by prioritising:
- the question-at-hand;
- appropriate forms of methodological bracketing;
- distinct methodological steps in research; and
- "[t]he specific combinations of all the above in composite forms of research."
Discovers the "meso-level of ontology between the abstract, philosophical level of ontology and the in-situ, ontic level." Strong structuration allows varied abstract ontological concepts in experiential conditions.
Focuses on the meso-level at the temporal and spatial scale.
Conceptualises independent causal forces and irresistible causal forces, which take into account how external structures, internal structures, and active agency affect agent choices (or lack of them). "Irresistible forces" are the connected concepts of a horizon of action with a set of "actions-in-hand" and a hierarchical ordering of purposes and concerns. An agent is affected by external influences. This aspect of strong structuration helps reconcile an agent's dialectic of control and his/her more constrained set of "real choices."

Post-structuration and dualism

Margaret Archer objected to the inseparability of structure and agency in structuration theory. She proposed a notion of dualism rather than "duality of structure". She primarily examined structural frameworks and the action within the limits allowed by those conditions. She combined realist ontology and called her methodology analytical dualism. Archer maintained that structure precedes agency in social structure reproduction and analytical importance, and that they should be analysed separately. She emphasised the importance of temporality in social analysis, dividing it into four stages: structural conditioning, social interaction, its immediate outcome and structural elaboration. Thus her analysis considered embedded "structural conditions, emergent causal powers and properties, social interactions between agents, and subsequent structural changes or reproductions arising from the latter." Archer criticised structuration theory for denying time and place because of the inseparability between structure and agency.

Nicos Mouzelis reconstructed Giddens' original theories. Mouzelis kept Giddens' original formulation of structure as "rules and resources." However, he was considered a dualist, because he argued for dualism to be as important in social analysis as the duality of structure. Mouzelis reexamined human social action at the "syntagmatic" (syntactic) level. He claimed that the duality of structure does not account for all types of social relationships. Duality of structure works when agents do not question or disrupt rules, and interaction resembles "natural/performative" actions with a practical orientation. However, in other contexts, the relationship between structure and agency can resemble dualism more than duality, such as systems that are the result of powerful agents. In these situations, rules are not viewed as resources, but are in states of transition or redefinition, where actions are seen from a "strategic/monitoring orientation." In this orientation, dualism shows the distance between agents and structures. He called these situations "syntagmatic duality". For example, a professor can change the class he or she teaches, but has little capability to change the larger university structure. "In that case, syntagmatic duality gives way to syntagmatic dualism." This implies that systems are the outcome, but not the medium, of social actions. Mouzelis also criticised Giddens' lack of consideration for social hierarchies.

John Parker built on Archer and Mouzelis's support for dualism to propose a theoretical reclamation of historical sociology and macro-structures using concrete historical cases, claiming that dualism better explained the dynamics of social structures. Equally, Robert Archer developed and applied analytical dualism in his critical analysis of the impact of New Managerialism on education policy in England and Wales during the 1990sand organization theory.

John B. Thompson

Though he agreed with the soundness and overall purposes of Giddens' most expansive structuration concepts (i.e., against dualism and for the study of structure in concert with agency), John B. Thompson ("a close friend and colleague of Giddens at Cambridge University") wrote one of the most widely cited critiques of structuration theory. His central argument was that it needed to be more specific and more consistent both internally and with conventional social structure theory. Thompson focused on problematic aspects of Giddens' concept of structure as "rules and resources," focusing on "rules". He argued that Giddens' concept of rule was too broad.

Thompson claimed that Giddens presupposed a criterion of importance in contending that rules are a generalizable enough tool to apply to every aspect of human action and interaction; "on the other hand, Giddens is well aware that some rules, or some kinds or aspects of rules, are much more important than others for the analysis of, for example, the social structure of capitalist societies." He found the term to be imprecise and to not designate which rules are more relevant for which social structures.

Thompson used the example of linguistic analysis to point out that the need for a prior framework which to enable analysis of, for example, the social structure of an entire nation. While semantic rules may be relevant to social structure, to study them "presupposes some structural points of reference which are not themselves rules, with regard to which [of] these semantic rules are differentiated" according to class, sex, region and so on. He called this structural differentiation.

Rules differently affect variously situated individuals. Thompson gave the example of a private school which restricts enrollment and thus participation. Thus rules—in this case, restrictions—"operate differentially, affecting unevenly various groups of individuals whose categorization depends on certain assumptions about social structures." The isolated analysis of rules does not incorporate differences among agents.

Thompson claimed that Giddens offered no way of formulating structural identity. Some "rules" are better conceived of as broad inherent elements that define a structure's identity (e.g., Henry Ford and Harold Macmillan are "capitalistic"). These agents may differ, but have important traits in common due to their "capitalistic" identity. Thompson theorized that these traits were not rules in the sense that a manager could draw upon a "rule" to fire a tardy employee; rather, they were elements which "limit the kinds of rules which are possible and which thereby delimit the scope for institutional variation." It is necessary to outline the broader social system to be able to analyze agents, actors, and rules within that system.

Thus Thompson concluded that Giddens' use of the term "rules" is problematic. "Structure" is similarly objectionable: "But to adhere to this conception of structure, while at the same time acknowledging the need for the study of 'structural principles,' 'structural sets' and 'axes of structuration,' is simply a recipe for conceptual confusion."

Thompson proposed several amendments. He requested sharper differentiation between the reproduction of institutions and the reproduction of social structure. He proposed an altered version of the structuration cycle. He defined "institutions" as "characterized by rules, regulations and conventions of various sorts, by differing kinds and quantities of resources and by hierarchical power relations between the occupants of institutional positions." Agents acting within institutions and conforming to institutional rules and regulations or using institutionally endowed power reproduce the institution. "If, in so doing, the institutions continue to satisfy certain structural conditions, both in the sense of conditions which delimit the scope for institutional variation and the conditions which underlie the operation of structural differentiation, then the agents may be said to reproduce social structure."

Thompson also proposed adding a range of alternatives to Giddens' conception of constraints on human action. He pointed out the paradoxical relationship between Giddens' "dialectic of control" and his acknowledgement that constraints may leave an agent with no choice. He demanded that Giddens better show how wants and desires relate to choice.

Giddens replied that a structural principle is not equivalent with rules, and pointed to his definition from A Contemporary Critique of Historical Materialism: "Structural principles are principles of organisation implicated in those practices most "deeply" (in time) and "pervasively" (in space) sedimented in society", and described structuration as a "mode of institutional articulation" with emphasis on the relationship between time and space and a host of institutional orderings including, but not limited to, rules.

Ultimately, Thompson concluded that the concept of structure as "rules and resources" in an elemental and ontological way resulted in conceptual confusion. Many theorists supported Thompson's argument that an analysis "based on structuration's ontology of structures as norms, interpretative schemes and power resources radically limits itself if it does not frame and locate itself within a more broadly conceived notion of social structures."

Change

Sewell provided a useful summary that included one of the theory's less specified aspects: the question "Why are structural transformations possible?" He claimed that Giddens' overrelied on rules and modified Giddens' argument by re-defining "resources" as the embodiment of cultural schemas. He argued that change arises from the multiplicity of structures, the transposable nature of schemas, the unpredictability of resource accumulation, the polysemy of resources and the intersection of structures.

The existence of multiple structures implies that the knowledgeable agents whose actions produce systems are capable of applying different schemas to contexts with differing resources, contrary to the conception of a universal habitus (learned dispositions, skills and ways of acting). He wrote that "Societies are based on practices that derived from many distinct structures, which exist at different levels, operate in different modalities, and are themselves based on widely varying types and quantities of resources. ...It is never true that all of them are homologous."

Originally from Bourdieu, transposable schemas can be "applied to a wide and not fully predictable range of cases outside the context in which they were initially learned." That capacity "is inherent in the knowledge of cultural schemas that characterizes all minimally competent members of society."

Agents may modify schemas even though their use does not predictably accumulate resources. For example, the effect of a joke is never quite certain, but a comedian may alter it based on the amount of laughter it garners regardless of this variability.

Agents may interpret a particular resource according to different schemas. E.g., a commander could attribute his wealth to military prowess, while others could see it as a blessing from the gods or a coincidental initial advantage.

Structures often overlap, confusing interpretation (e.g., the structure of capitalist society includes production from both private property and worker solidarity).

Technology

This theory was adapted and augmented by researchers interested in the relationship between technology and social structures, such as information technology in organizations. DeSanctis and Poole proposed an "adaptive structuration theory" with respect to the emergence and use of group decision support systems. In particular, they chose Giddens' notion of modalities to consider how technology is used with respect to its "spirit". "Appropriations" are the immediate, visible actions that reveal deeper structuration processes and are enacted with "moves". Appropriations may be faithful or unfaithful, be instrumental and be used with various attitudes.

Wanda Orlikowski applied the duality of structure to technology: "The duality of technology identifies prior views of technology as either objective force or as socially constructed product–as a false dichotomy." She compared this to previous models (the technological imperative, strategic choice, and technology as a trigger) and considered the importance of meaning, power, norms, and interpretive flexibility. Orlikowski later replaced the notion of embedded properties for enactment (use). The "practice lens" shows how people enact structures which shape their use of technology that they employ in their practices. While Orlikowski's work focused on corporations, it is equally applicable to the technology cultures that have emerged in smaller community-based organizations, and can be adapted through the gender sensitivity lens in approaches to technology governance.

Workman, Ford and Allen rearticulated structuration theory as structuration agency theory for modeling socio-biologically inspired structuration in security software. Software agents join humans to engage in social actions of information exchange, giving and receiving instructions, responding to other agents, and pursuing goals individually or jointly.

Four-flows-model

The four flows model of organizing is grounded in structuration theory. McPhee and Pamela Zaug (2001) identify four communication flows that collectively perform key organizational functions and distinguish organizations from less formal social groups:

Membership negotiation—socialization, but also identification and self-positioning;
Organizational self-structuring—reflexive, especially managerial, structuring and control activities;
Activity coordination—Interacting to align or adjust local work activities;
Institutional positioning in the social order of institutions—mostly external communication to gain recognition and inclusion in the web of social transactions.

Group communication

Poole, Seibold, and McPhee wrote that "group structuration theory," provides "a theory of group interaction commensurate with the complexities of the phenomenon."

The theory attempts to integrate macrosocial theories and individuals or small groups, as well as how to avoid the binary categorization of either "stable" or "emergent" groups.

Waldeck et al. concluded that the theory needs to better predict outcomes, rather than merely explaining them. Decision rules support decision-making, which produces a communication pattern that can be directly observable. Research has not yet examined the "rational" function of group communication and decision-making (i.e., how well it achieves goals), nor structural production or constraints. Researchers must empirically demonstrate the recursivity of action and structure, examine how structures stabilize and change over time due to group communication, and may want to integrate argumentation research.

Public relations

Falkheimer claimed that integrating structuration theory into public relations (PR) strategies could result in a less agency-driven business, return theoretical focus to the role of power structures in PR, and reject massive PR campaigns in favor of a more "holistic understanding of how PR may be used in local contexts both as a reproductive and [transformational] social instrument." Falkheimer portrayed PR as a method of communication and action whereby social systems emerge and reproduce. Structuration theory reinvigorates the study of space and time in PR theory. Applied structuration theory may emphasize community-based approaches, storytelling, rituals, and informal communication systems. Moreover, structuration theory integrates all organizational members in PR actions, integrating PR into all organizational levels rather than a separate office. Finally, structuration reveals interesting ethical considerations relating to whether a social system should transform.

COVID-19 and structure

the COVID-19 pandemic had huge impact on society since the beginning. When investigating those impacts, many researchers found helpful using structuration theory to explain the change in society. Oliver (2021) used “a theoretical framework derived from Giddens’ structuration theory to analyze societal information cultures, concentrating on information and health literacy perspectives.” And this framework focused on “the three modalities of structuration, i.e., interpretive schemes, resources, and norms.” And in Oliver’s research, those three modalities are “resources”, “information freedom” and “formal and informal concepts and rules of behavior”. After analyzing four countries framework, Oliver and his research team concluded “All our case studies show a number of competing information sources – from traditional media and official websites to various social media platforms used by both the government and the general public – that complicate the information landscape in which we all try to navigate what we know, and what we do not yet know, about the pandemic.”

In the research of interpreting how remote work environment change during COVID-19 in South Africa, Walter (2020) applied structuration theory because “it addresses the relationship between actors (or persons) and social structures and how these social structures ultimately realign and conform to the actions of actors” Plus, “these social structures from Giddens's structuration theory assist people to navigate through everyday life.”

Zvokuomba (2021) also used Giddens' theory of structuration “to reflect at the various levels of fragilities within the context of COVID-19 lockdown measures.” One example in the research is that “theory of structuration and agency point to situations when individuals and groups of people either in compliance or defiance of community norms and rules of survival adopt certain practices.” And during pandemic, researched pointed out “reverting to the traditional midwifery became a pragmatic approach to a problem.” One example to support this point is that “As medical centers were partly closed, with no basic medication and health staff, the only alternative was seek traditional medical services. ”

Business and structure

Structuration theory can also be used in explaining business related issues including operating, managing and marketing.

Clifton Scott and Karen Myers (2010)studied how the duality of structure can explain the shifts of members' actions during the membership negotiations in an organization by This is an example of how structure evolves with the interaction of a group of people.

Another case study done by Dutta (2016) and his research team shows how the models shift because of the action of individuals. The article examines the relationship between CEO’s behavior and a company’s cross-border acquisition. This case can also demonstrate one of the major dimensions in the duality of structure, the sense of power from the CEO. Authors found out that the process follows the theory of duality of structure: under the circumstances of CEO is overconfident, and the company is the limitation of resources, the process of cross-border acquisition is likely to be different than before.

Yuan ElaineJ (2011)’s research focused on a certain demographic of people under the structure. Authors studied Chinese TV shows and audiences’ flavor of the show. The author concludes in the relationship between the audience and the TV shows producers, audiences’ behavior has higher-order patterns.

Pavlou and Majchrzak argued that research on business-to-business e-commerce portrayed technology as overly deterministic. The authors employed structuration theory to re-examine outcomes such as economic/business success as well as trust, coordination, innovation, and shared knowledge. They looked beyond technology into organizational structure and practices, and examined the effects on the structure of adapting to new technologies. The authors held that technology needs to be aligned and compatible with the existing "trustworthy" practices and organizational and market structure. The authors recommended measuring long-term adaptations using ethnography, monitoring and other methods to observe causal relationships and generate better predictions.

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Wednesday, July 6, 2022

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