In this phylogenetic tree, the green group is paraphyletic;
it is composed of a common ancestor (the lowest green vertical stem)
and some of its descendants, but it excludes the blue group (a
monophyletic group) which diverged from the green group.
Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic with respect to the excluded subgroups. In contrast, a monophyletic grouping (a clade) includes a common ancestor and all of its descendants.
The term received currency during the debates of the 1960s and 1970s accompanying the rise of cladistics, having been coined by zoologist Willi Hennig to apply to well-known taxa like Reptilia (reptiles), which is paraphyletic with respect to birds.
Reptilia contains the last common ancestor of reptiles and all
descendants of that ancestor except for birds. Other commonly recognized
paraphyletic groups include fish, monkeys, lizards,, wasps, and crustaceans.
Etymology
The term paraphyly, or paraphyletic, derives from the two Ancient Greek words παρά (pará), meaning "beside, near", and φῦλον (phûlon), meaning "genus, species", and refers to the situation in which one or several monophyletic subgroups of organisms (e.g., genera, species) are left apart from all other descendants of a unique common ancestor.
Conversely, the term monophyly, or monophyletic, builds on the Ancient Greek prefix μόνος (mónos), meaning "alone, only, unique", and refers to the fact that a monophyletic group includes organisms consisting of all the descendants of a unique common ancestor.
By comparison, the term polyphyly, or polyphyletic, uses the Ancient Greek prefix πολύς (polús), meaning "many, a lot of". and refers to the fact that a polyphyletic group includes organisms arising from multiple ancestral sources.
Phylogenetics
Cladogram of the primates, showing a monophyly (the simians, in yellow), a paraphyly (the prosimians, in blue, including the red patch), and a polyphyly (the night-active primates, the lorises and the tarsiers, in red). "Monkeys" too are paraphyletic if apes and humans are excluded.
Groups that include all the descendants of a common ancestor are said to be monophyletic. A paraphyletic group is a monophyletic group from which one or more subsidiary clades
(monophyletic groups) are excluded to form a separate group.
Philosopher of science Marc Ereshefsky has argued that paraphyletic taxa
are the result of anagenesis in the excluded group or groups. A cladistic approach normally does not grant paraphyletic assemblages
the status of "groups", nor does it reify them with explanations, as in
cladistics they are not seen as the actual products of evolutionary
events.
A group whose identifying features evolved convergently in two or more lineages is polyphyletic (Greek πολύς [polys],
"many"). More broadly, any taxon that is not paraphyletic or
monophyletic can be called polyphyletic. Empirically, the distinction
between polyphyletic groups and paraphyletic groups is rather arbitrary,
since the character states of common ancestors are inferences, not
observations.
These terms were developed during the debates of the 1960s and 1970s accompanying the rise of cladistics.
Paraphyletic groupings are considered problematic by many
taxonomists, as it is not possible to talk precisely about their
phylogenetic relationships, their characteristic traits and literal
extinction. Related terms are stem group, chronospecies, budding cladogenesis, anagenesis, or 'grade'
groupings. Paraphyletic groups are often relics from outdated
hypotheses of phylogenic relationships from before the rise of
cladistics.
Examples
Wasps are paraphyletic, consisting of the cladeApocrita without ants and bees, which are not usually considered to be wasps; the sawflies ("Symphyta") too are paraphyletic, as the Apocrita are nested inside the Symphytan clades.
The prokaryotes (single-celled life forms without cell nuclei) are a paraphyletic grouping, because they exclude the eukaryotes, a descendant group. Bacteria and Archaea
are prokaryotes, but archaea and eukaryotes share a common ancestor
that is not ancestral to the bacteria. The prokaryote/eukaryote
distinction was proposed by Edouard Chatton in 1937 and was generally accepted after being adopted by Roger Stanier and
C.B. van Niel in 1962. The botanical code (the ICBN, now the ICN) abandoned consideration of bacterial nomenclature in 1975; currently, prokaryotic nomenclature is regulated under the ICNB with a starting date of 1 January 1980 (in contrast to a 1753 start date under the ICBN/ICN).
Among plants, dicotyledons (in the traditional sense) are paraphyletic because the group excludes monocotyledons. "Dicotyledon" has not been used as a botanic classification for decades, but is allowed as a synonym of Magnoliopsida. Phylogenetic analysis indicates that the monocots are a development from a dicot ancestor. Excluding monocots from the dicots makes the latter a paraphyletic group.
Among animals, several familiar groups are not, in fact, clades. The order Artiodactyla (even-toed ungulates) as traditionally defined is paraphyletic because it excludes Cetaceans (whales, dolphins, etc.). Under the ranks of the ICZN Code,
the two taxa are separate orders. Molecular studies, however, have
shown that the Cetacea descend from artiodactyl ancestors, although the
precise phylogeny within the order remains uncertain. Without the
Cetaceans the Artiodactyls are paraphyletic. The class Reptilia is paraphyletic because it excludes birds (class Aves).
Under a traditional classification, these two taxa are separate
classes. However birds are sister taxon to a group of dinosaurs (part of
Diapsida), both of which are "reptiles".
Osteichthyes, bony fish, are paraphyletic when circumscribed to include only Actinopterygii (ray-finned fish) and Sarcopterygii (lungfish, etc.), and to exclude tetrapods; more recently, Osteichthyes is treated as a clade, including the tetrapods.
The "wasps" are paraphyletic, consisting of the narrow-waisted Apocrita without the ants and bees. The sawflies (Symphyta) are similarly paraphyletic, forming all of the Hymenoptera except for the Apocrita, a clade deep within the sawfly tree. Crustaceans are not a clade because the Hexapoda (insects) are excluded. The modern clade that spans all of them is the Pancrustacea.
One of the goals of modern taxonomy over the past fifty years has
been to eliminate paraphyletic taxa from formal classifications. Below is a partial list of obsolete taxa and informal groups that have been found to be paraphyletic.
Species have a special status in systematics as being an observable feature of nature itself and as the basic unit of classification. Some articulations of the phylogenetic species concept
require species to be monophyletic, but paraphyletic species are common
in nature, to the extent that they do not have a single common
ancestor. Indeed, for sexually reproducing taxa, no species has a
"single common ancestor" organism. Paraphyly is common in speciation, whereby a mother species (a paraspecies) gives rise to a daughter species without itself becoming extinct. Research indicates as many as 20 percent of all animal species and between 20 and 50 percent of plant species are paraphyletic. Accounting for these facts, some taxonomists argue that paraphyly is a
trait of nature that should be acknowledged at higher taxonomic levels.
Cladists advocate a phylogenetic species concept that does not consider species to exhibit the properties of monophyly
or paraphyly, concepts under that perspective which apply only to groups
of species. They consider Zander's extension of the "paraphyletic species" argument to higher taxa to represent a category error.
Uses for paraphyletic groups
When the appearance of significant traits has led a subclade on
an evolutionary path very divergent from that of a more inclusive clade,
it often makes sense to study the paraphyletic group that remains
without considering the larger clade. For example, the Neogene evolution of the Artiodactyla (even-toed ungulates, like deer, cows, pigs and hippopotamuses - Cervidae, Bovidae, Suidae and Hippopotamidae,
the families that contain these various artiodactyls, are all
monophyletic groups) has taken place in environments so different from
that of the Cetacea
(whales, dolphins, and porpoises) that the Artiodactyla are often
studied in isolation even though the cetaceans are a descendant group.
The prokaryote group is another example; it is paraphyletic because it is composed of two Domains (Eubacteria and Archaea) and excludes (the eukaryotes). It is very useful because it has a clearly defined and significant distinction (absence of a cell nucleus, a plesiomorphy) from its excluded descendants.
Also, some systematists recognize paraphyletic groups as being
involved in evolutionary transitions, the development of the first
tetrapods from their ancestors for example. Any name given to these
hypothetical ancestors to distinguish them from tetrapods—"fish", for
example—necessarily picks out a paraphyletic group, because the
descendant tetrapods are not included. Other systematists consider reification of paraphyletic groups to obscure inferred patterns of evolutionary history.
The term "evolutionary grade" is sometimes used for paraphyletic groups. Moreover, the concepts of monophyly, paraphyly, and polyphyly have been used in deducing key genes for barcoding of diverse group of species.
The concept of paraphyly has also been applied to historical linguistics, where the methods of cladistics have found some utility in comparing languages. For instance, the Formosan languages form a paraphyletic group of the Austronesian languages because they consist of the nine branches of the Austronesian family that are not Malayo-Polynesian and are restricted to the island of Taiwan.
The last known thylacine (Tasmanian tiger), photographed at Hobart Zoo in 1933.
An endling is the last known individual of a species or subspecies. Once the endling dies, the species becomes extinct. The word was coined in correspondence in the scientific journal Nature.
Usage
The 4 April 1996 issue of Nature published a correspondence in which commentators suggested that a new word, endling, be adopted to denote the last individual of a species.The 23 May issue of Nature published several counter-suggestions, including ender, terminarch, and relict.
The word endling appeared on the walls of the National Museum of Australia in Tangled Destinies,
a 2001 exhibition by Matt Kirchman and Scott Guerin, about the
relationship between Australian peoples and their land. In the
exhibition, the definition, as it appeared in Nature, was printed in
large letters on the wall above two specimens of the extinct Tasmanian tiger:
"Endling (n.) The last surviving individual of a species of animal or
plant". A printed description of this exhibition offered a similar
definition, omitting reference to plants: "An endling is the name given
to an animal that is the last of its species."
In The Flight of the Emu: A Hundred Years of Australian Ornithology 1901-2001, author Libby Robin stated that "the very last individual of a species" is "what scientists refer to as an 'endling'".
In 2011, the word was used in the Earth Island Journal, in an essay by Eric Freedman entitled "Extinction Is Forever: A Quest for the Last Known Survivors". Freedman defined endling as "the last known specimen of her species."
In "The Sense of an Endling", author Helen Lewis describes the
notion of an endling as poignant, and the word as "wonderfully
Tolkien-esque".
Author Eric Freedman describes endling as "a word with
finality", stating, "It is deep-to-the-bone chilling to know the exact
date a species disappeared from Earth. It is even more ghastly to look
upon the place where it happened and know that nobody knew or cared at
the time what had transpired and why."
This is not a comprehensive list of contemporary extinction, but a list of high-profile, widely publicised examples of when the last individual of a species was known.
Birds
A dusky seaside sparrow (Ammospiza maritima nigrescens), officially declared extinct in 1990.
The passenger pigeon (Ectopistes migratorius) became extinct at 1 p.m. on 1 September 1914 with the death of Martha, the last surviving member of the species, at the Cincinnati Zoo.
Incas, the last known Carolina parakeet (Conuropsis carolinensis), died, also at the Cincinnati Zoo (and in the same cage as Martha), on 21 February 1918. He died within one year of his mate, Lady Jane. The species was officially declared extinct in 1939.
Booming Ben, a solitary heath hen (Tympanuchus cupido cupido), was last seen 11 March 1932 on Martha's Vineyard, Massachusetts.
The last known Kauaʻi ʻōʻō (Moho braccatus) was recorded singing a mating call on Kauai in 1987 by David Boynton. The bird is believed to have been killed by Hurricane Iniki in 1992, and the death of this individual also marked the extinction of the entire Mohoidae family.
Mammals
In 1627, the last aurochs (Bos primigenius), an ancestor of bovine and cattle, died in a forest near what is now Jaktorów in modern-day Poland.A quagga mare at the London Zoo in 1870. This is the only specimen photographed alive.
The quagga (Equus quagga quagga)
became extinct in the wild in the late 1870s due to hunting for meat
and skins, and the subspecies' endling died in captivity on 12 August
1883 at the Artis in Amsterdam.
The final tarpan (Equus ferus ferus) died in captivity in the Russian Empire in 1903.
On 7 September 1936, the last known captive thylacine (Thylacinus cynocephalus), also called Tasmanian tiger, died in Hobart Zoo,
following persecution of the species through hunting and trapping.
Information published about this individual has been conflicted
throughout the decades following its death. An individual named Frank Darby invented the myth that it was named
"Benjamin", and the claim was rapidly circulated by media and persists
until today, even being repeated by Wikipedia itself. Other areas of contention include where it was captured and by whom, by
whom it was captured, whether it was neglected in its zoo enclosure and
even whether it was the last known surviving thylacine. Researchers Robert Paddle and Kathryn Medlock argue that the endling
was female and died of neglect, while Gareth Linnard affirms that it was
male (despite not being named Benjamin) and died of old age, citing its
valued status in the zoo's collection. Regardless, the thylacine at Hobart Zoo is the last reputably-verified
specimen of not only its species and genus, but also the entire family Thylacinidae. However, some individuals, such Barry Brooks
and his colleagues, argue the thylacine probably persisted in the wild
for several decades following the captive individual's death in 1936.
The last known Mexican grizzly bear (Ursus arctos horribilis), also called oso plateado (silver bear) in Spanish, was shot in 1976 in Sonora, Mexico.
Taxidermised body of Celia, the final Pyrenean ibex
Celia, the last Pyrenean ibex (Capra pyrenaica pyrenaica), was found crushed by a tree on 6 January 2000 in the Spanish Pyrenees, after hunting and competition from livestock reduced the population to one individual.
Turgi was the last Partula clarkei, a Polynesian tree snail, who died on 31 January 1996 in the London Zoo.
A tank in the Bristol Zoo was the last refuge of Partula faba, a land snail from Ra'iātea in French Polynesia. The population dropped from 38 in 2012 to one in 2015. The last individual died on 21 February 2016.
Only one living specimen of the tree species Madhuca diplostemon is known to exist.
Some seeds were found in an archaeological excavation in the Judean desert in 1986–87. In 2009, a specimen of an unknown species of Commiphora was successfully sprouted from one of these ancient seeds (dated 993 CE – 1202 calCE). The tree was named Sheba. In 2024, it was tentatively identified as tsori
or Judean balsam, on the basis of taxonomy and resin properties
matching ancient descriptions. Similar to Fernanda, Sheba is the only
known individual of its species despite recent discovery or rediscovery.
Determinism is the metaphysical view that all events within the universe (or multiverse) can occur only in one possible way. Deterministic theories throughout the history of philosophy have
developed from diverse and sometimes overlapping motives and
considerations. Like eternalism, determinism focuses on particular events rather than the future as a concept. Determinism is often contrasted with free will, although some philosophers argue that the two are compatible. The antonym of determinism is indeterminism, the view that events are not deterministically caused.
Historically, debates about determinism have involved many
philosophical positions and given rise to multiple varieties or
interpretations of determinism. One topic of debate concerns the scope
of determined systems. Some philosophers have maintained that the entire
universe is a single determinate system, while others identify more
limited determinate systems. Another common debate topic is whether
determinism and free will can coexist; compatibilism and incompatibilism represent the opposing sides of this debate.
Determinism should not be confused with the self-determination
of human actions by reasons, motives, and desires. Determinism is about
interactions which affect cognitive processes in people's lives. It is about the cause and the result of what people have done. Cause
and result are always bound together in cognitive processes. It assumes
that if an observer has sufficient information about an object or human
being, then such an observer might be able to predict every consequent
move of that object or human being. Determinism rarely requires that
perfect prediction be practically possible.
Causal determinism posits that every event results from preceding
events and natural laws, while nomological determinism emphasizes the
predictability of the future from past and present states. Necessitarianism claims only one possible world exists, and predeterminism suggests events are fixed in advance, sometimes biologically or genetically. Fatalism and theological determinism attribute outcomes to fate or divine omniscience, whereas adequate determinism and interpretations of quantum mechanics
explore probabilistic or emergent constraints on macroscopic phenomena.
Philosophical varieties extend to human behavior, including biological,
psychological, social, and cultural determinism, as well as structural
determinism, which highlights systemic constraints. Historically,
determinism appears in both Western traditions, from the Presocratics and Stoics to Newtonian mechanics, and Eastern thought, including karma, Ājīvika fatalism, and Buddhist
dependent origination. Modern science recognizes deterministic models
in classical physics and complex generative processes, while quantum
mechanics introduces probabilistic and debated interpretations.
Varieties
Determinism may commonly refer to any of the following viewpoints:
Causal
Causal determinism, sometimes synonymous with historical determinism (a sort of path dependence), is "the idea that every event is necessitated by antecedent events and conditions together with the laws of nature." However, it is a broad enough term to consider that:
...One's
deliberations, choices, and actions will often be necessary links in
the causal chain that brings something about. In other words, even
though our deliberations, choices, and actions are themselves determined
like everything else, it is still the case, according to causal
determinism, that the occurrence or existence of yet other things
depends upon our deliberating, choosing and acting in a certain way.
Causal
determinism proposes that there is an unbroken chain of prior
occurrences stretching back to the origin of the universe. The relation
between events and the origin of the universe may not be specified.
Causal determinists believe that there is nothing in the universe that
has no cause or is self-caused.
Causal determinism has also been considered more generally as the idea
that everything that happens or exists is caused by antecedent
conditions. In the case of nomological determinism, these conditions are considered
events also, implying that the future is determined completely by
preceding events—a combination of prior states of the universe and the
laws of nature. These conditions can also be considered metaphysical in origin (such as in the case of theological determinism).
Many philosophical theories of determinism frame themselves with the idea that reality follows a sort of predetermined path.
Nomological
Nomological determinism is the most common form of causal determinism and is generally synonymous with physical determinism. This is the notion that the past and the present dictate the future
entirely and necessarily by rigid natural laws and that every occurrence
inevitably results from prior events. Nomological determinism is
sometimes illustrated by the thought experiment of Laplace's demon. Laplace
posited that an omniscient observer, knowing with infinite precision
all the positions and velocities of every particle in the universe,
could predict the future entirely. Ernest Nagel viewed determinism in terms of a physical state, declaring a theory to be deterministic if it predicts a state at other times uniquely from values at one given time.
Necessitarianism
Necessitarianism is a metaphysical principle that denies all mere possibility and maintains that there is only one possible way for the world to exist. Leucippus claimed there are no uncaused events and that everything occurs for a reason and by necessity.
Predeterminism
Predeterminism is the idea that all events are determined in advance. The concept is often argued by invoking causal determinism, implying that there is an unbroken chain of prior occurrences
stretching back to the origin of the universe. In the case of
predeterminism, this chain of events has been pre-established, and human
actions cannot interfere with the outcomes of this pre-established
chain.
Predeterminism can be categorized as a specific type of determinism when it is used to mean pre-established causal determinism. It can also be used interchangeably with causal determinism—in the context of its capacity to determine future events. However, predeterminism is often considered as independent of causal determinism.
Biological
The term predeterminism is also frequently used in the context of biology and heredity, in which case it represents a form of biological determinism, sometimes called genetic determinism. Biological determinism is the idea that all human behaviors, beliefs, and desires are fixed by human genetic nature.
Friedrich Nietzsche explained that human beings are "determined" by their bodies and are subject to its passions, impulses, and instincts.
Fatalism
Fatalism is normally distinguished from determinism, as a form of teleological determinism. Fatalism is the idea that everything is fated to happen, resulting in humans having no control over their future. Fate has arbitrary power, and does not necessarily follow any causal or deterministic laws. Types of fatalism include hard theological determinism and the idea of predestination, where there is a God
who determines all that humans will do. This may be accomplished
through either foreknowledge of their actions, achieved through omniscience or by predetermining their actions.
Theological
Theological determinism is a form of determinism that holds that all events that happen are either preordained (i.e., predestined) to happen by a monotheisticdeity, or are destined to occur given its omniscience. Two forms of theological determinism exist, referred to as strong and weak theological determinism.
Strong theological determinism is based on the concept of a creator deity
dictating all events in history: "everything that happens has been
predestined to happen by an omniscient, omnipotent divinity."
Weak theological determinism is based on the concept of divine
foreknowledge—"because God's omniscience is perfect, what God knows
about the future will inevitably happen, which means, consequently, that
the future is already fixed." There exist slight variations on this categorization, however. Some
claim either that theological determinism requires predestination of all
events and outcomes by the divinity—i.e., they do not classify the
weaker version as theological determinism unless libertarian free will is assumed to be denied as a consequence—or that the weaker version does not constitute theological determinism at all.
With respect to free will, "theological determinism is the thesis
that God exists and has infallible knowledge of all true propositions
including propositions about our future actions", more minimal criteria
designed to encapsulate all forms of theological determinism.
Theological determinism can also be seen as a form of causal
determinism, in which the antecedent conditions are the nature and will
of God. Some have asserted that Augustine of Hippo
introduced theological determinism into Christianity in 412 CE, whereas
all prior Christian authors supported free will against Stoic and
Gnostic determinism. However, there are many Biblical passages that seem to support the idea of some kind of theological determinism.
Adequate
Adequate determinism is the idea, because of quantum decoherence, that quantum indeterminacy can be ignored for most macroscopic events. Random quantum events "average out" in the limit of large numbers of particles (where the laws of quantum mechanics
asymptotically approach the laws of classical mechanics). While there
are specific examples of these random events magnified to macro levels,
such as Geiger counters, they are still insignificant in the context of
free will.
Determined probability
Stephen Hawking
explained that the microscopic world of quantum mechanics is one of
determined probabilities. That is, nature is not governed by laws that
determine the future with certainty but by laws that determine the
probability of various futures.
Many-worlds interpretation
The many-worlds interpretation
of quantum mechanics accepts the linear causal sets of sequential
events with adequate consistency yet also suggests constant forking of
causal chains that can in principle be globally deterministic. Meaning the causal set of events leading to the present are all valid
yet appear as a singular linear time stream within a much broader unseen
conic probability field of other outcomes that "split off" from the
locally observed timeline. Under this model causal sets are still
"consistent" yet not exclusive to singular iterated outcomes.
The interpretation sidesteps the exclusive retrospective causal
chain problem of "could not have done otherwise" by suggesting "the
other outcome does exist" in a set of parallel states of the universe
that (in one version) split off in any interacting event. This
interpretation is sometimes described with the example of agent-based
choices.
Philosophical varieties
Nature/nurture controversy
Although some of the above forms of determinism concern human behaviors and cognition, others frame themselves as an answer to the debate on nature and nurture.
They will suggest that one factor will entirely determine behavior. As
scientific understanding has grown, however, the strongest versions of
these theories have been widely rejected as a single-cause fallacy. In other words, the modern deterministic theories attempt to explain how the interaction of both nature and nurture is entirely predictable. The concept of heritability has been helpful in making this distinction.
Biological determinism, sometimes called genetic determinism, is the idea that each of human behaviors, beliefs, and desires are fixed by human genetic nature.
Behaviorism involves the idea that all behavior can be traced to specific causes—either environmental or reflexive. John B. Watson and B. F. Skinner developed this nurture-focused determinism.
Cultural materialism, contends that the physical world impacts and sets constraints on human behavior.
Other "deterministic" theories actually seek only to highlight the importance of a particular
factor in predicting the future. These theories often use the factor as
a sort of guide or constraint on the future. They need not suppose that
complete knowledge of that one factor would allow the making of perfect
predictions.
Psychological determinism can mean that humans must act according to reason, but it can also be synonymous with some sort of psychological egoism. The latter is the view that humans will always act according to their perceived best interest.
Linguistic determinism proposes that language determines (or at least limits) the things that humans can think and say and thus know. The Sapir–Whorf hypothesis argues that individuals experience the world based on the grammatical structures they habitually use.
Technological determinism is the theory that a society's technology drives the development of its social structure and cultural values.
Structural
Structural
determinism is the philosophical view that actions, events, and
processes are predicated on and determined by structural factors. Given any particular structure or set of estimable components, it is a
concept that emphasizes rational and predictable outcomes. Chilean
biologists Humberto Maturana and Francisco Varela
popularized the notion, writing that a living system's general order is
maintained via a circular process of ongoing self-referral, and thus
its organization and structure defines the changes it undergoes. According to the authors, a system can undergo changes of state
(alteration of structure without loss of identity) or disintegrations
(alteration of structure with loss of identity). Such changes or
disintegrations are not ascertained by the elements of the disturbing
agent, as each disturbance will only trigger responses in the respective
system, which in turn, are determined by each system's own structure.
On an individualistic
level, what this means is that human beings as free and independent
entities are triggered to react by external stimuli or change in
circumstance. However, their own internal state and existing physical
and mental capacities determine their responses to those triggers. On a
much broader societal level, structural determinists believe that larger
issues in the society—especially those pertaining to minorities and
subjugated communities—are predominantly assessed through existing
structural conditions, making change of prevailing conditions difficult,
and sometimes outright impossible. For example, the concept has been
applied to the politics of race in the United States of America and other Western countries such as the United Kingdom and Australia, with structural determinists lamenting structural factors for the prevalence of racism in these countries. Additionally, Marxists have conceptualized the writings of Karl Marx within the context of structural determinism as well. For example, Louis Althusser, a structural Marxist,
argued that the state, in its political, economic, and legal
structures, reproduces the discourse of capitalism, in turn, allowing
for the burgeoning of capitalistic structures.
Proponents of the notion highlight the usefulness of structural
determinism to study complicated issues related to race and gender, as
it highlights often gilded structural conditions that block meaningful
change. Critics call it too rigid, reductionist and inflexible. Additionally,
they also criticize the notion for overemphasizing deterministic forces
such as structure over the role of human agency and the ability of the
people to act. These critics argue that politicians, academics, and
social activists have the capability to bring about significant change
despite stringent structural conditions.
Philosophers have debated both the truth of determinism, and the
truth of free will. This creates the four possible positions in the
figure. Compatibilism refers to the view that free will is, in some sense, compatible with determinism. The three incompatibilist positions deny this possibility. The hard incompatibilists hold that free will is incompatible with both determinism and indeterminism, the libertarians that determinism does not hold, and free will might exist, and the hard determinists that determinism does hold and free will does not exist. The Dutch philosopher Baruch Spinoza
was a determinist thinker, and argued that human freedom can be
achieved through knowledge of the causes that determine desire and
affections. He defined human servitude as the state of bondage of anyone
who is aware of their own desires, but ignorant of the causes that
determined them. However, the free or virtuous person becomes capable,
through reason and knowledge, to be genuinely free, even as they are
being "determined". For the Dutch philosopher, acting out of one's own
internal necessity is genuine freedom
while being driven by exterior determinations is akin to bondage.
Spinoza's thoughts on human servitude and liberty are respectively
detailed in the fourth and fifth volumes of his work Ethics.
The standard argument against free will, according to philosopher J. J. C. Smart, focuses on the implications of determinism for free will. He suggests free will is denied whether determinism is true or not. He
says that if determinism is true, all actions are predicted and no one
is assumed to be free; however, if determinism is false, all actions are
presumed to be random and as such no one seems free because they have
no part in controlling what happens.
With the soul
Some determinists argue that materialism
does not present a complete understanding of the universe, because
while it can describe determinate interactions among material things, it
ignores the minds or souls of conscious beings.
Mecca Chiesa notes that the probabilistic or selectionistic determinism of B. F. Skinner comprised a wholly separate conception of determinism that was not mechanistic
at all. Mechanistic determinism assumes that every event has an
unbroken chain of prior occurrences, but a selectionistic or
probabilistic model does not.
Western tradition
In the West, some elements of determinism have been expressed in Greece from the 6th century BCE by the PresocraticsHeraclitus and Leucippus. The first notions of determinism appears to originate with the Stoics, as part of their theory of universal causal determinism. The resulting philosophical debates, which involved the confluence of
elements of Aristotelian Ethics with Stoic psychology, led in the
1st–3rd centuries CE in the works of Alexander of Aphrodisias to the first recorded Western debate over determinism and freedom, an issue that is known in theology as the paradox of free will. The writings of Epictetus as well as middle Platonist and early Christian thought were instrumental in this development. Jewish philosopher Moses Maimonides said of the deterministic implications of an omniscient god: "Does God know or does He not know that a certain individual will be
good or bad? If thou sayest 'He knows', then it necessarily follows that
[that] man is compelled to act as God knew beforehand he would act,
otherwise God's knowledge would be imperfect."
Newtonian mechanics
Determinism in the West is often associated with Newtonian mechanics/physics,
which depicts the physical matter of the universe as operating
according to a set of fixed laws. The "billiard ball" hypothesis, a
product of Newtonian physics, argues that once the initial conditions of
the universe have been established, the rest of the history of the
universe follows inevitably. If it were actually possible to have
complete knowledge of physical matter and all of the laws governing that
matter at any one time, then it would be theoretically possible to
compute the time and place of every event that will ever occur (Laplace's demon).
In this sense, the basic particles of the universe operate in the same
fashion as the rolling balls on a billiard table, moving and striking
each other in predictable ways to produce predictable results.
Whether or not it is all-encompassing in so doing, Newtonian
mechanics deals only with caused events; for example, if an object
begins in a known position and is hit dead on by an object with some
known velocity, then it will be pushed straight toward another
predictable point. If it goes somewhere else, the Newtonians argue, one
must question one's measurements of the original position of the object,
the exact direction of the striking object, gravitational or other
fields that were inadvertently ignored, etc. Then, they maintain,
repeated experiments and improvements in accuracy will always bring
one's observations closer to the theoretically predicted results. When
dealing with situations on an ordinary human scale, Newtonian physics
has been successful. But it fails as velocities become some substantial
fraction of the speed of light and when interactions at the atomic scale are studied. Before the discovery of quantum
effects and other challenges to Newtonian physics, "uncertainty" was
always a term that applied to the accuracy of human knowledge about
causes and effects, and not to the causes and effects themselves.
Newtonian mechanics, as well as any following physical theories,
are results of observations and experiments, and so they describe "how
it all works" within a tolerance. However, old western scientists
believed if there are any logical connections found between an observed
cause and effect, there must be also some absolute natural laws behind.
Belief in perfect natural laws driving everything, instead of just
describing what we should expect, led to searching for a set of
universal simple laws that rule the world. This movement significantly
encouraged deterministic views in Western philosophy, as well as the related theological views of classical pantheism.
The views on the interaction of karma and free will are numerous, and diverge from each other. For example, in Sikhism,
god's grace, gained through worship, can erase one's karmic debts, a
belief which reconciles the principle of karma with a monotheistic god
one must freely choose to worship. Jainists believe in compatibilism,
in which the cycle of Saṃsara is a completely mechanistic process,
occurring without any divine intervention. The Jains hold an atomic view
of reality, in which particles of karma form the fundamental
microscopic building material of the universe.
Ājīvika
In ancient India, the Ājīvika school of philosophy founded by Makkhali Gosāla (around 500 BCE), otherwise referred to as "Ājīvikism" in Western scholarship, upheld the Niyati ("Fate") doctrine of absolute fatalism or determinism, which negates the existence of free will and karma, and is therefore considered one of the nāstika or "heterodox" schools of Indian philosophy. The oldest descriptions of the Ājīvika fatalists and their founder Gosāla can be found both in the Buddhist and Jaina scriptures of ancient India. The predetermined fate of all sentient beings and the impossibility to achieve liberation (mokṣa) from the eternal cycle of birth, death, and rebirth (saṃsāra) was the major distinctive philosophical and metaphysical doctrine of this heterodox school of Indian philosophy,annoverated among the other Śramaṇa movements that emerged in India during the Second urbanization (600–200 BCE).
Buddhist philosophy
contains several concepts which some scholars describe as deterministic
to various levels. However, the direct analysis of Buddhist metaphysics
through the lens of determinism is difficult, due to the differences
between European and Buddhist traditions of thought.
One concept which is argued to support a hard determinism is the doctrine of dependent origination (pratītyasamutpāda) in the early Buddhist texts, which states that all phenomena (dharma) are necessarily caused by some other phenomenon, which it can be said to be dependent
on, like links in a massive, never-ending chain; the basic principle is
that all things (dharmas, phenomena, principles) arise in dependence
upon other things, which means that they are fundamentally "empty" or devoid of any intrinsic, eternal essence and therefore are impermanent. In traditional Buddhist philosophy, this concept is used to explain the functioning of the eternal cycle of birth, death, and rebirth (saṃsāra); all thoughts and actions exert a karmic force that attaches to the individual's consciousness, which will manifest through reincarnation and results in future lives. In other words, righteous or unrighteous actions in one life will
necessarily cause good or bad responses in another future life or more
lives. The early Buddhist texts and later Tibetan Buddhist scriptures associate dependent arising with the fundamental Buddhist doctrines of emptiness (śūnyatā) and non-self (anattā).
Another Buddhist concept which many scholars perceive to be deterministic is the doctrine of non-self (anattā). In Buddhism, attaining enlightenment involves one realizing that neither in humans nor any other sentient beings
there is a fundamental core of permanent being, identity, or
personality which can be called the "soul", and that all sentient beings
(including humans) are instead made of several, constantly changing factors which bind them to the eternal cycle of birth, death, and rebirth (saṃsāra). Sentient beings are composed of the five aggregates of existence (skandha): matter, sensation, perception, mental formations, and consciousness. In the Saṃyutta Nikāya of the Pāli Canon, the historical Buddha
is recorded as saying that "just as the word 'chariot' exists on the
basis of the aggregation of parts, even so the concept of 'being' exists
when the five aggregates are available." The early Buddhist texts outline different ways in which dependent
origination is a middle way between different sets of "extreme" views
(such as "monist" and "pluralist" ontologies or materialist and dualist views of mind-body relation). In the Kaccānagotta Sutta of the Pāli Canon (SN 12.15, parallel at SA 301), the historical Buddha
stated that "this world mostly relies on the dual notions of existence
and non-existence" and then explains the right view as follows:
But when you truly see the origin
of the world with right understanding, you won't have the notion of
non-existence regarding the world. And when you truly see the cessation
of the world with right understanding, you won't have the notion of
existence regarding the world.
Some Western scholars argue that the concept of non-self necessarily disproves the ideas of free will and moral responsibility.If there is no autonomous self, in this view, and all events are
necessarily and unchangeably caused by others, then no type of autonomy
can be said to exist, moral or otherwise. However, other scholars disagree, claiming that the Buddhist conception of the universe allows for a form of compatibilism. Buddhism perceives reality occurring on two different levels: the ultimate reality, which can only be truly understood by the enlightened ones, and the illusory or false reality of the material world, which is considered to be "real" or "true" by those who are ignorant about the nature of metaphysical reality; i.e., those who still haven't achieved enlightenment. Therefore, Buddhism perceives free will as a notion belonging to the illusory belief in the unchanging self or personhood
that pertains to the false reality of the material world, while
concepts like non-self and dependent origination belong to the ultimate
reality; the transition between the two can be truly understood,
Buddhists claim, by one who has attained enlightenment.
Although it was once thought by scientists that any indeterminism in
quantum mechanics occurred at too small a scale to influence biological
or neurological systems, there is indication that nervous systems are influenced by quantum indeterminism due to chaos theory. It is unclear what implications this has for the problem of free will given various possible reactions to the problem in the first place. Many biologists do not grant determinism: Christof Koch, for instance, argues against it, and in favour of libertarian free will, by making arguments based on generative processes (emergence). Other proponents of emergentist or generative philosophy, cognitive sciences, and evolutionary psychology, argue that a certain form of determinism (not necessarily causal) is true. They suggest instead that an illusion of free will is experienced due to the generation of infinite behaviour from the interaction of finite-deterministic set of rules and parameters.
Thus the unpredictability of the emerging behaviour from deterministic
processes leads to a perception of free will, even though free will as
an ontological entity does not exist.
An animation of Conway's Game of Life, where the interaction of just four simple rules creates patterns that seem somehow "alive"
As an illustration, the strategy board-games chess and Go have rigorous rules in which no information (such as cards' face-values) is hidden from either player and no random
events (such as dice-rolling) happen within the game. Yet, chess and
especially Go with its extremely simple deterministic rules, can still
have an extremely large number of unpredictable moves. When chess is
simplified to 7 or fewer pieces, however, endgame tables are available
that dictate which moves to play to achieve a perfect game. This implies
that, given a less complex environment (with the original 32 pieces
reduced to 7 or fewer pieces), a perfectly predictable game of chess is
possible. In this scenario, the winning player can announce that a
checkmate will happen within a given number of moves, assuming a perfect
defense by the losing player, or fewer moves if the defending player
chooses sub-optimal moves as the game progresses into its inevitable,
predicted conclusion. By this analogy, it is suggested, the experience
of free will emerges from the interaction of finite rules and
deterministic parameters that generate nearly infinite and practically
unpredictable behavioural responses. In theory, if all these events
could be accounted for, and there were a known way to evaluate these
events, the seemingly unpredictable behaviour would become predictable.Another hands-on example of generative processes is John Horton Conway's playable Game of Life. Nassim Taleb is wary of such models, and coined the term "ludic fallacy."
Compatibility with the existence of science
Certain philosophers of science
argue that, while causal determinism (in which everything including the
brain/mind is subject to the laws of causality) is compatible with
minds capable of science, fatalism and predestination is not. These
philosophers make the distinction that causal determinism means that
each step is determined by the step before and therefore allows sensory
input from observational data to determine what conclusions the brain
reaches, while fatalism in which the steps between do not connect an
initial cause to the results would make it impossible for observational
data to correct false hypotheses. This is often combined with the
argument that if the brain had fixed views and the arguments were mere
after-constructs with no causal effect on the conclusions, science would
have been impossible and the use of arguments would have been a
meaningless waste of energy with no persuasive effect on brains with
fixed views.
Mathematical models
Many mathematical models of physical systems are deterministic. This is true of most models involving differential equations
(notably, those measuring rate of change over time). Mathematical
models that are not deterministic because they involve randomness are
called stochastic. Because of sensitive dependence on initial conditions,
some deterministic models may appear to behave non-deterministically;
in such cases, a deterministic interpretation of the model may not be
useful due to numerical instability and a finite amount of precision
in measurement. Such considerations can motivate the consideration of a
stochastic model even though the underlying system is governed by
deterministic equations.
Since the beginning of the 20th century, quantum mechanics—the
physics of the extremely small—has revealed previously concealed aspects
of events. Before that, Newtonian physics—the physics of everyday life—dominated. Taken in isolation (rather than as an approximation
to quantum mechanics), Newtonian physics depicts a universe in which
objects move in perfectly determined ways. At the scale where humans
exist and interact with the universe, Newtonian mechanics remain useful,
and make relatively accurate predictions (e.g. calculating the
trajectory of a bullet). But whereas in theory, absolute knowledge
of the forces accelerating a bullet would produce an absolutely
accurate prediction of its path, modern quantum mechanics casts
reasonable doubt on this main thesis of determinism.
This doubt takes radically different forms. The observed results of quantum mechanics are random but various interpretations of quantum mechanics
make different assumptions about determinism which cannot be
distinguished experimentally. The standard interpretation widely used by
physicists is not deterministic, but the other interpretations have
been devised which are deterministic.
Standard quantum mechanics
These
are five of the infinitely many paths available for a particle to move
from point A at time t to point B at time t’(>t).
Quantum mechanics is the product of a careful application of the scientific method, logic and empiricism.
Through a large number of careful experiments physicists developed a
rather unintuitive mental model: A particle's path cannot be specified
in from its quantum description. "Path" is a classical, practical
attribute in everyday life, but one that quantum particles do not
possess. Quantum mechanics attributes probability to all possible paths
and asserts the only one outcome will be observed.
The randomness in quantum mechanics derives from the quantum
aspect of the model. Different experimental results are obtained for
each individual quanta. Only the probability can predicted.
As Stephen Hawking explains, the result is not traditional determinism, but rather determined probabilities. As far as the thesis of determinism is concerned, these probabilities, at least, are quite determined.
Although
it is not possible to predict the arrival position or time for any
particle, probabilities of arrival predict the final pattern of events.
On the topic of predictable probabilities, the double-slit experiments are a popular example. Photons
are fired one-by-one through a double-slit apparatus at a distant
screen. They do not arrive at any single point, nor even the two points
lined up with the slits (the way it might be expected of bullets fired
by a fixed gun at a distant target). Instead, the photons arrive in
varying concentrations and times across the screen, and only the final
distribution of photons can be predicted. In that sense the behavior of
light in this apparatus is predictable, but there is no way to predict
where or when in the resulting interference pattern any single photon will make its contribution.
Some (including Albert Einstein) have argued that the inability to predict any more than probabilities is simply due to ignorance.[86] The idea is that, beyond the conditions and laws can be observed or deduced, there are also hidden factors or "hidden variables" that determine absolutely
in which order photons reach the detector screen. They argue that the
course of the universe is absolutely determined, but that humans are
screened from knowledge of the determinative factors. So, they say, it
only appears that things proceed in a probabilistically way.
John S. Bell analyzed Einstein's work in his famous Bell's theorem,
which demonstrates that quantum mechanics can makes statistical
predictions that would be violated if local hidden variables really
existed. Many experiments have verified the quantum predictions.
Other interpretations
Bell's theorem only applies to local
hidden variables. Quantum mechanics can be formulated with non-local
hidden variables to achieve a deterministic theory that is in agreement
with experiment. An example is the Bohm interpretation
of quantum mechanics. Bohm's Interpretation, though, violates special
relativity and it is highly controversial whether or not it can be
reconciled without giving up on determinism.
The Many worlds interpretation focuses on the deterministic nature of the Schrodinger's equation.
For any closed system, including the entire universe, the wavefunction
solutions to this equation evolve deterministically. The apparent
randomness of observations corresponds to branching of the wavefunction,
with one world for each possible outcome.
Another foundational assumption to quantum mechanics is that of free will, which has been argued to be foundational to the scientific method as a whole. Bell acknowledged that abandoning this assumption would both allow for the maintenance of determinism as well as locality. This perspective is known as superdeterminism, and is defended by some physicists such as Sabine Hossenfelder and Tim Palmer.
More advanced variations on these arguments include quantum contextuality, by Bell, Simon B. Kochen and Ernst Specker,
which argues that hidden variable theories cannot be "sensible",
meaning that the values of the hidden variables inherently depend on the
devices used to measure them.
This debate is relevant because there are possibly specific
situations in which the arrival of an electron at a screen at a certain
point and time would trigger one event, whereas its arrival at another
point would trigger an entirely different event (e.g. see Schrödinger's cat—a thought experiment used as part of a deeper debate).
In his 1939 address "The Relation between Mathematics and Physics", Paul Dirac
pointed out that purely deterministic classical mechanics cannot
explain the cosmological origins of the universe; today the early
universe is modeled quantum mechanically.
Nevertheless, the question of determinism in modern physics remains debated. On one hand, Albert Einstein's theory of relativity,
which represents an advancement over Newtonian mechanics, is based on a
deterministic framework. On the other hand, Einstein himself resisted
the indeterministic view of quantum mechanics, as evidenced by his
famous debates with Niels Bohr, which continued until his death.
Moreover, chaos theory
highlights that even within a deterministic framework, the ability to
precisely predict the evolution of a system is often limited. A
deterministic system may appear random: two apparently identical
starting points can result in vastly different results. Such dynamical systems are sensitive to initial conditions.
Even if the universe followed a strict deterministic order, the human
capacity to predict every event and comprehend all underlying causes
would still be constrained this kind of sensitivity.
Adequate determinism (see Varieties, above) is the reason that Stephen Hawking called libertarian free will "just an illusion".
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