Is Most Life in the Universe Lithophilic?

by Paul Gilster on January 11, 2019

Original link:  https://www.centauri-dreams.org/2019/01/11/is-most-life-in-the-universe-lithophilic/ 

Seeking life on other worlds necessarily makes us examine our assumptions about the detectability of living things in extreme environments. We’re learning that our own planet supports life in regions we once would have ruled out for survival, and as we examine such extremophiles, it makes sense to wonder how similar organisms might have emerged elsewhere. Pondering these questions in today’s essay, Centauri Dreams regular Alex Tolley asks whether we are failing to consider possibly rich biospheres that could thrive without the need for surface water.

By Alex Tolley

Image: An endolithic lifeform showing as a green layer a few millimeters inside a clear rock. The rock has been split open. Antarctica. Credit: https://en.wikipedia.org/wiki/Endolith#/media/File:Cryptoendolith.jpg, Creative Commons).

A policeman sees a drunk man searching for something under a streetlight and asks what the drunk has lost. He says he lost his keys and they both look under the streetlight together. After a few minutes the policeman asks if he is sure he lost them here, and the drunk replies, no, and that he lost them in the park. The policeman asks why he is searching here, and the drunk replies, “this is where the light is” – The Streetlight Effect

I’m going to make a bold claim that we are searching for life where the starlight can reach, and not where it is most common, in the lithosphere.

 

One of the outstanding big questions is whether life is common or rare in the universe. With the rapid discovery of thousands of exoplanets, the race is now on to determine if any of those planets have life. This means using spectroscopic techniques to find proxies, such as atmospheric composition, chlorophyll “red edge”, and other signatures that indicate life as we know it. There is the exciting prospect that new telescopes and instruments will give us the answer to whether life exists elsewhere within a decade or two.

The search for life on exoplanets starts with locating rocky planets in the habitable zone (HZ). The HZ is defined as potentially having liquid surface water, which requires an atmosphere dense enough to ensure that water is retained. While complex, multicellular life that visibly populates our planet is the vision most people have of life, as I have argued previously [13], it is most likely that we will detect the signatures of bacterial life, particularly archaean methanogens, as prokaryotes were the only form of life on Earth for over 85% of its existence. Most worlds in the HZ will probably look more like Venus or Mars, either too dry and/or with an insufficient atmosphere to allow surface water. Such worlds will be bypassed for more attractive Earth analogs.

This is particularly important for the most common star type, the M-dwarfs. These stars are often downgraded as having habitable planets due to the flaring of their stars which can strip atmospheres and irradiate the surface. This reduces the likelihood for life at the surface, and for many, is a showstopper.

However, if life established well below the surface, these factors affecting the surface become relatively unimportant. All stars, including M-dwarfs, may well have a retinue of living worlds, but with their life undetectable by current means.

Despite mid-20th-century hopes for multicellular life to be found on Mars or Venus, it is now clear that the surfaces of these planets are devoid of any sort of multicellular based ecosystems. Venus’ surface is too hot for any carbon-based life to survive. The various Martian orbiters and landers have found no multicellular life, and so far no unambiguous evidence of microbial life on or near the surface. The Moon is the only world where surface rock samples have been returned to Earth, and these samples suggest, unsurprisingly, that the lunar surface is sterile [10,12].

NASA’s mantra for the search for life, echoing the HZ requirement, is “Follow the water!” On its face, this makes the lunar surface unlikely as a habitat, similarly Mars, although Mars’ does have an abundance of frozen water below the surface. This leaves the subsurface icy moons as the current favorite for the discovery of life in our solar system, particularly around any hypothetical “hot vents” that mimic Earth’s.

However, when following the trail of liquid water, we now know that the Earth has a huge inventory of water in the mantle, providing a new source of water for the crustal rocks. This water is most likely primordial, sourced from the chondritic material during formation.[6,9] If the Earth has primordial water in the mantle, so might the Moon, as it was formed from the same material as the Earth. A recent analysis of lunar rocks indicates that the bulk of the water in the Moon is also primordial, with concentrations only an order of magnitude less than the water in the Earth’s mantle [1]. While we know Mars has water just below the surface, the same argument about primordial water deep within Mars also follows.

The question then becomes whether this water is in a form suitable for life. Is there a zone in these worlds where water is both liquid and at a temperature below the maximum we know terrestrial thermophiles can survive?

Table 1 below shows some estimates for Earth, Mars and the Moon where a suitable liquid water temperature range exists. The estimated thermal gradients are used to suggest the depths where life might start to be found as temperatures and pressures result in liquid water, and the maximum depth life might survive.

On Earth, the reference planet, the high thermal gradient, and warm surface suggest life can be found at any depth, up to about 5 – 6 km. The Moon, due to a low thermal gradient might only have a habitable zone starting at 15 km below the surface but reaching down to nearly 120 km. Mars is intermediate, with a habitable zone 6-29 km in extent.

Table 1. Estimates of thermal gradients and range of depths where water is liquid, but below 120C as a current approximate maximum for thermophiles

World	Surface C	Thermal gradient	Depth (km) at 120C (with 0C at surface)	Depth (km) at 0C with surface temp	Depth (km) at 120C with surface temp
Earth	14	20-30	4-6	0	3.5-5
Mars	-63	6.4-10.6 **	11-19	6-10	18-29
Moon	-18 *	1.17 ***	103	15	118

* Assumes the Moon surface temperature would be the same as the Earth without an atmosphere
** [7]
*** [8]

So we have 2 possible rocky worlds in our solar system that may have water reservoirs in their mantles due to primordial asteroids and therefore liquid water in their lithospheres deep below the surface, protected from radiation and with fairly constant temperatures within the range of terrestrial organisms. So our necessary condition of liquid water may exist in these worlds, rather than at the surface.

Given that liquid water may be found deep below the surface, is there any evidence that life exists there too?

In 1999, the iconoclast astrophysicist and astronomer Thomas Gold published a popular account of his theory that fossil fuels were not derived from biological sources, but rather from primordial methane that was contaminated by organisms living deep within the Earth’s crust.[4,5]. While his theory remains controversial, his suggestion that organisms live in the lithosphere has been proven correct. [11]. Bores have shown that microorganisms have been found living at least 4 km below the surface. It has been suggested that the biomass of these organisms may exceed that of humanity on Earth, so life in the lithosphere is not trivial compared to that on the surface of our planet.

Figure 1. Illustration of the search for life in the lithosphere. At this time, life has been found at depths of nearly 4 km, but absent at 9 km where the temperatures were too high.
 

1. Deep-sea, manned submersibles and remotely operated vehicles collect fluid samples that exit natural points of access to the oceanic crust, such as underwater volcanoes or hydrothermal vents. These samples contain microbes living in the crust beneath.
 

2. Drilling holes into the Earth’s crust allows retrieval of rock and sediment cores reaching kilometers below the surface. The holes can then be filled with monitoring equipment to make long-term measurements of the deep biosphere.
 

3. Deep mines provide access points for researchers to journey into the Earth’s continental crust, from where they can drill even deeper into the ground or search for microbes living in water seeping directly out of the rock.
 

Source: [11]

From the article:

To date, studies of crustal sites all over the world—both oceanic and continental—have documented all sorts of organisms getting by in environments that, until recently, were deemed inhospitable, with some theoretical estimates now suggesting life might survive at least 10 kilometers into the crust. And the deep biosphere doesn’t just comprise bacteria and archaea, as once thought; researchers now know that the subsurface contains various fungal species, and even the occasional animal. Following the 2011 discovery of nematode worms in a South African gold mine, an intensive two-year survey turned up members of four invertebrate phyla—flatworms, rotifers, segmented worms, and arthropods—living 1.4 kilometers below the Earth’s surface.

With our existence proof of a deep, hot biosphere in Earth, is it possible that similar life could exist in the lithospheres of other rocky worlds in our solar system, including our Moon?

Mars is particularly attractive, as there is evidence Mars was both warmer and wetter in the past. There was geologic activity as clearly evident by the Tharsis bulge and the shield volcanoes like Olympus Mons. We know there is frozen water below the surface on Mars. What we are not certain of is whether Mars’ core is still molten and hot, and what the areothermal gradient is. One of the scientific goals of the Insight lander, currently on Mars, is to determine heat flow in Mars. This will help provide the data necessary to determine the range of the habitable zone in the lithosphere.

In contrast, we do have samples of Moon rock. An analysis of the Apollo 11 samples showed that organic material was present, but there was no sign of life except for terrestrial contamination [10, 12]. Since then, very little effort has been applied to look for life in the lunar rocks. The theory that the Moon is desiccated, hostile to life, and sterile, seems to have deterred further work. The early analyses indicated that methane (CH4) is present in the Apollo 11 samples. This may be primordial or delivered subsequently by impacts from asteroids or comets. If we ever discovered pockets of natural gas, even petroleum, on the Moon, this would be a staggering confirmation of Gold’s theory.

So where should we look?

Although the Moon is in our proverbial backyard, the expected depth of liquid water starts well below the bottom of the deepest craters.. This suggests that either deep boring would be necessary, or we must hope for impact ejecta to be recoverable from the needed depths. The prospects for either seem rather remote, although scientific and commercial activities on the Moon might make this possible in this century.

Despite its remoteness, Mars may be more attractive. Sampling at the bottom of crater walls and the sides of the Valles Marineris may give us relatively easy access to samples at the needed depths. Should the transient dark marks on the sides of crater walls prove to be liquid water, we would have samples within easy reach. The recent discovery of a possible subsurface water deposit just 1.5 km beneath the surface of Mars might be another possible target to reach.

The requirement that water is a necessary, but insufficient, condition for life has focused efforts on looking for life where liquid surface water exists. Because of the available techniques, exoplanet targets will be those that satisfy the HZ requirements. While these may prove the first confirmation of extraterrestrial life, they cannot answer some of the fundamental questions that we would like to know, for example, is abiogenesis common, or rare, and is panspermia the means to spread life. For that, we will need samples of such life. For the foreseeable future, that means sampling the solar system. We have 2 nearby worlds, and Gold suggested that there might be 10 suitable Moon-sized and above worlds that might have deep biospheres [5]. That might be ample.

To date, our search for life beyond Earth has been little more than looking for fish in the waves lapping the shore. We need to search more comprehensively. I am arguing that this search needs to focus on the habitable regions of lithospheres of any suitable rocky world. We might start with signs of bacterial fossils in exposed rock strata and ejecta, and then core samples taken from boreholes to look for living organisms. Finding life, especially that from a different genesis would indicate that life is indeed ubiquitous in the universe.

References

1. Barnes, J. J., Tartèse, R., Anand, M., Mccubbin, F. M., Franchi, I. A., Starkey, N. A., & Russell, S. S. (2014). The origin of water in the primitive Moon as revealed by the lunar highlands samples. Earth and Planetary Science Letters, 390, 244-252. doi:10.1016/j.epsl.2014.01.015
2. Davies, P. C., Benner, S. A., Cleland, C. E., Lineweaver, C. H., Mckay, C. P., & Wolfe-Simon, F. (2009). Signatures of a Shadow Biosphere. Astrobiology, 9(2), 241-249. doi:10.1089/ast.2008.0251
3. Davies, P. C. (2011). ​ The eerie silence: Renewing our search for alien intelligence. ​ Boston: Mariner Books, Houghton Mifflin Harcourt.
4. Gold, T. (1992). The deep, hot biosphere. Proceedings of the National Academy of Sciences, 89(13), 6045-6049. doi:10.1073/pnas.89.13.6045
5. Gold, T. (2010). ​ The deep hot biosphere: The myth of fossil fuels. New York, NY: Copernicus Books.
6. Hallis, L. J., Huss, G. R., Nagashima, K., Taylor, G. J., Halldórsson, S. A., Hilton, D. R., . . . Meech, K. J. (2015). Evidence for primordial water in Earth’s deep mantle. Science, 350(6262), 795-797. doi:10.1126/science.aac4834
7. Hoffman N.(2001) Modern geothermal gradients on Mars and implications for subsurface liquids. Conference on the Geophysical Detection of Subsurface Water on Mars (2001)
8. Kuskov O (2018) Geochemical Constraints on the Cold and Hot Models of the Moon’s Interior: 1–Bulk Composition. Solar System Research, 2018, Vol. 52, No. 6, pp. 467–479.
9. Mccubbin, F. M., Steele, A., Hauri, E. H., Nekvasil, H., Yamashita, S., & Hemley, R. J. (2010). Nominally hydrous magmatism on the Moon. Proceedings of the National Academy of Sciences, 107(25), 11223-11228. doi:10.1073/pnas.1006677107
10. Nagy, B., Drew, C. M., Hamilton, P. B., Modzeleski, V. E., Murphy, S. M., Scott, W. M., . . . Young, M. (1970). Organic Compounds in Lunar Samples: Pyrolysis Products, Hydrocarbons, Amino Acids. Science, 167(3918), 770-773. doi:10.1126/science.167.3918.770
11. Offord, C. (2018) Life Thrives Within the Earth’s Crust. The Scientist, October 1, 2018.
12. Oyama, V. I., Merek, E. L., & Silverman, M. P. (1970). A Search for Viable Organisms in a Lunar Sample. Science,167(3918), 773-775. doi:10.1126/science.167.3918.773
13. Tolley, A Detecting Early Life on Exoplanets. Centauri Dreams, February 2018
14. Way, M. J., Genio, A. D., Kiang, N. Y., Sohl, L. E., Grinspoon, D. H., Aleinov, I., . . . Clune, T. (2016). Was Venus the first habitable world of our solar system? Geophysical Research Letters, 43(16), 8376-8383. doi:10.1002/2016gl069790
15. Woo, M. The Hunt for Earth’s Deep Hidden Oceans. Quanta Magazine, July 11, 2018

Critical theory

From Wikipedia, the free encyclopedia

Critical theory is the reflective assessment and critique of society and culture by applying knowledge from the social sciences and the humanities. As a term, critical theory has two meanings with different origins and histories: the first originated in sociology and the second originated in literary criticism, whereby it is used and applied as an umbrella term that can describe a theory founded upon critique; thus, the theorist Max Horkheimer described a theory as critical insofar as it seeks "to liberate human beings from the circumstances that enslave them."

 

In sociology and political philosophy, the term "Critical Theory" describes the Western Marxist philosophy of the Frankfurt School, which was developed in Germany in the 1930s. This use of the term requires proper noun capitalization, whereas "a critical theory" or "a critical social theory" may have similar elements of thought, but not stress its intellectual lineage specifically to the Frankfurt School. Frankfurt School critical theorists drew on the critical methods of Karl Marx and Sigmund Freud. Critical theory maintains that ideology is the principal obstacle to human liberation. Critical theory was established as a school of thought primarily by the Frankfurt School theoreticians Herbert Marcuse, Theodor Adorno, Max Horkheimer, Walter Benjamin, and Erich Fromm. Modern critical theory has additionally been influenced by György Lukács and Antonio Gramsci, as well as the second generation Frankfurt School scholars, notably Jürgen Habermas. In Habermas's work, critical theory transcended its theoretical roots in German idealism and progressed closer to American pragmatism. Concern for social "base and superstructure" is one of the remaining Marxist philosophical concepts in much of contemporary critical theory.

Postmodern critical theory politicizes social problems "by situating them in historical and cultural contexts, to implicate themselves in the process of collecting and analyzing data, and to relativize their findings."

Overview

Critical theory (German: Kritische Theorie) was first defined by Max Horkheimer of the Frankfurt School of sociology in his 1937 essay Traditional and Critical Theory: Critical Theory is a social theory oriented toward critiquing and changing society as a whole, in contrast to traditional theory oriented only to understanding or explaining it. Horkheimer wanted to distinguish critical theory as a radical, emancipatory form of Marxian theory, critiquing both the model of science put forward by logical positivism and what he and his colleagues saw as the covert positivism and authoritarianism of orthodox Marxism and Communism. He described a theory as critical insofar as it seeks "to liberate human beings from the circumstances that enslave them". Critical theory involves a normative dimension, either through criticizing society from some general theory of values, norms, or "oughts", or through criticizing it in terms of its own espoused values.

The core concepts of critical theory are as follows:

1. That critical social theory should be directed at the totality of society in its historical specificity (i.e. how it came to be configured at a specific point in time), and
2. That critical theory should improve understanding of society by integrating all the major social sciences, including geography, economics, sociology, history, political science, anthropology, and psychology.

This version of "critical" theory derives from Kant's (18th-century) and Marx's (19th-century) use of the term "critique", as in Kant's Critique of Pure Reason and Marx's concept that his work Das Kapital (Capital) forms a "critique of political economy". For Kant's transcendental idealism, "critique" means examining and establishing the limits of the validity of a faculty, type, or body of knowledge, especially through accounting for the limitations imposed by the fundamental, irreducible concepts in use in that knowledge system. 

Kant's notion of critique has been associated with the overturning of false, unprovable, or dogmatic philosophical, social, and political beliefs, because Kant's critique of reason involved the critique of dogmatic theological and metaphysical ideas and was intertwined with the enhancement of ethical autonomy and the Enlightenment critique of superstition and irrational authority. Ignored by many in "critical realist" circles, however, is that Kant's immediate impetus for writing his "Critique of Pure Reason" was to address problems raised by David Hume's skeptical empiricism which, in attacking metaphysics, employed reason and logic to argue against the knowability of the world and common notions of causation. Kant, by contrast, pushed the employment of a priori metaphysical claims as requisite, for if anything is to be said to be knowable, it would have to be established upon abstractions distinct from perceivable phenomena.

Marx explicitly developed the notion of critique into the critique of ideology and linked it with the practice of social revolution, as stated in the famous 11th of his Theses on Feuerbach: "The philosophers have only interpreted the world, in various ways; the point is to change it."

One of the distinguishing characteristics of critical theory, as Adorno and Horkheimer elaborated in their Dialectic of Enlightenment (1947), is a certain ambivalence concerning the ultimate source or foundation of social domination, an ambivalence which gave rise to the "pessimism" of the new critical theory over the possibility of human emancipation and freedom. This ambivalence was rooted, of course, in the historical circumstances in which the work was originally produced, in particular, the rise of National Socialism, state capitalism, and mass culture as entirely new forms of social domination that could not be adequately explained within the terms of traditional Marxist sociology.

For Adorno and Horkheimer, state intervention in economy had effectively abolished the tension between the "relations of production" and "material productive forces of society", a tension which, according to traditional critical theory, constituted the primary contradiction within capitalism. The market (as an "unconscious" mechanism for the distribution of goods) and private property had been replaced by centralized planning and socialized ownership of the means of production.

Yet, contrary to Marx's famous prediction in the Preface to a Contribution to the Critique of Political Economy, this shift did not lead to "an era of social revolution", but rather to fascism and totalitarianism. As such, critical theory was left, in Jürgen Habermas' words, without "anything in reserve to which it might appeal; and when the forces of production enter into a baneful symbiosis with the relations of production that they were supposed to blow wide open, there is no longer any dynamism upon which critique could base its hope". For Adorno and Horkheimer, this posed the problem of how to account for the apparent persistence of domination in the absence of the very contradiction that, according to traditional critical theory, was the source of domination itself.

In the 1960s, Jürgen Habermas, a proponent of critical social theory, raised the epistemological discussion to a new level in his Knowledge and Human Interests, by identifying critical knowledge as based on principles that differentiated it either from the natural sciences or the humanities, through its orientation to self-reflection and emancipation. Although unsatisfied with Adorno and Horkeimer's thought presented in Dialectic of Enlightenment, Habermas shares the view that, in the form of instrumental rationality, the era of modernity marks a move away from the liberation of enlightenment and toward a new form of enslavement. In Habermas's work, critical theory transcended its theoretical roots in German idealism, and progressed closer to American pragmatism.

Habermas is now influencing the philosophy of law in many countries—for example the creation of the social philosophy of law in Brazil, and his theory also has the potential to make the discourse of law one important institution of the modern world as a heritage of the Enlightenment.

His ideas regarding the relationship between modernity and rationalization are in this sense strongly influenced by Max Weber. Habermas dissolved further the elements of critical theory derived from Hegelian German Idealism, although his thought remains broadly Marxist in its epistemological approach. Perhaps his two most influential ideas are the concepts of the public sphere and communicative action; the latter arriving partly as a reaction to new post-structural or so-called "postmodern" challenges to the discourse of modernity. Habermas engaged in regular correspondence with Richard Rorty and a strong sense of philosophical pragmatism may be felt in his theory; thought which frequently traverses the boundaries between sociology and philosophy.

Critical theory and academic fields

Postmodern critical social theory

While modernist critical theory (as described above) concerns itself with "forms of authority and injustice that accompanied the evolution of industrial and corporate capitalism as a political-economic system," postmodern critical theory politicizes social problems "by situating them in historical and cultural contexts, to implicate themselves in the process of collecting and analyzing data, and to relativize their findings." Meaning itself is seen as unstable due to the rapid transformation in social structures. As a result, the focus of research is centered on local manifestations, rather than broad generalizations.

Postmodern critical research is also characterized by the crisis of representation, which rejects the idea that a researcher's work is an "objective depiction of a stable other". Instead, many postmodern scholars have adopted "alternatives that encourage reflection about the 'politics and poetics' of their work. In these accounts, the embodied, collaborative, dialogic, and improvisational aspects of qualitative research are clarified".

The term "critical theory" is often appropriated when an author works within sociological terms, yet attacks the social or human sciences (thus attempting to remain "outside" those frames of inquiry). Michel Foucault is one of these authors.

Jean Baudrillard has also been described as a critical theorist to the extent that he was an unconventional and critical sociologist; this appropriation is similarly casual, holding little or no relation to the Frankfurt School. Jürgen Habermas of The Frankfurt School is one of the key critics of postmodernism.

Critical theory is focused on language, symbolism, communication, and social construction.

Public relations

The critical theory allows public relations practitioners to recognize participatory planning by allowing previously unheard voices to be heard. Furthermore, this allows professionals the ability to create more specialized campaigns using the knowledge of other areas of study, moreover, it provides them with the ability to comprehend and change social institutions through advocacy. 

Communication studies

From the 1960s and 1970s onward, language, symbolism, text, and meaning came to be seen as the theoretical foundation for the humanities, through the influence of Ludwig Wittgenstein, Ferdinand de Saussure, George Herbert Mead, Noam Chomsky, Hans-Georg Gadamer, Roland Barthes, Jacques Derrida and other thinkers in linguistic and analytic philosophy, structural linguistics, symbolic interactionism, hermeneutics, semiology, linguistically oriented psychoanalysis (Jacques Lacan, Alfred Lorenzer), and deconstruction.

When, in the 1970s and 1980s, Jürgen Habermas redefined critical social theory as a study of communication, i.e. communicative competence and communicative rationality on the one hand, distorted communication on the other, the two versions of critical theory began to overlap to a much greater degree than before.

Pedagogy

Critical theorists have widely credited Paulo Freire for the first applications of critical theory towards education/pedagogy. They consider his best-known work, Pedagogy of the Oppressed, a seminal text in what is now known as the philosophy and social movement of critical pedagogy. For a history of the emergence of critical theory in the field of education, see Isaac Gottesman (2016), The Critical Turn in Education: From Marxist Critique to Postructuralist Feminism to Critical Theories of Race (New York: Routledge).

Criticism

While critical theorists have been frequently defined as Marxist intellectuals, their tendency to denounce some Marxist concepts and to combine Marxian analysis with other sociological and philosophical traditions has resulted in accusations of revisionism by classical, orthodox, and analytical Marxists, and by Marxist–Leninist philosophers. Martin Jay has stated that the first generation of critical theory is best understood as not promoting a specific philosophical agenda or a specific ideology, but as "a gadfly of other systems".

Critical theory has been criticized for not offering any clear road map to political action following critique, often explicitly repudiating any solutions (such as with Herbert Marcuse's concept of "the Great Refusal", which promoted abstaining from engaging in active political change).

Jurisprudence

From Wikipedia, the free encyclopedia

Philosophers of law ask "what is law, and what should it be?"

 

Jurisprudence or legal theory is the theoretical study of law, principally by philosophers but, from the twentieth century, also by social scientists. Scholars of jurisprudence, also known as jurists or legal theorists, hope to obtain a deeper understanding of legal reasoning, legal systems, legal institutions, and the role of law in society.

Modern jurisprudence began in the 18th century and was focused on the first principles of natural law, civil law, and the law of nations. General jurisprudence can be divided into categories both by the type of question scholars seek to answer and by the theories of jurisprudence, or schools of thought, regarding how those questions are best answered. Contemporary philosophy of law, which deals with general jurisprudence, addresses problems internal to law and legal systems and problems of law as a social institution that relates to the larger political and social context in which it exists.

This article addresses three distinct branches of thought in general jurisprudence. Ancient natural law is the idea that there are rational objective limits to the power of legislative rulers. The foundations of law are accessible through reason, and it is from these laws of nature that human laws gain whatever force they have. Analytic jurisprudence rejects natural law's fusing of what law is and what it ought to be. It espouses the use of a neutral point of view and descriptive language when referring to aspects of legal systems. It encompasses such theories of jurisprudence as "legal positivism", which holds that there is no necessary connection between law and morality and that the force of law comes from basic social facts; and "legal realism", which argues that the real-world practice of law determines what law is, the law having the force that it does because of what legislators, lawyers, and judges do with it. Normative jurisprudence is concerned with "evaluative" theories of law. It deals with what the goal or purpose of law is, or what moral or political theories provide a foundation for the law. It not only addresses the question "What is law?", but also tries to determine what the proper function of law should be, or what sorts of acts should be subject to legal sanctions, and what sorts of punishment should be permitted.

Etymology

The English word is derived from the Latin maxim jurisprudentia. Juris is the genitive form of jus meaning law, and prudentia means prudence (also: discretion, foresight, forethought, circumspection. It refers to the exercise of good judgment, common sense, and caution, especially in the conduct of practical matters. The word first appeared in written English in 1628, at a time when the word prudence meant knowledge of, or skill in, a matter. It may have entered English via the French jurisprudence, which appeared earlier.

History

Ancient Indian jurisprudence is mentioned in various Dharmaśāstra texts, starting with the Dharmasutra of Bhodhayana.

Jurisprudence in Ancient Rome had its origins with the (periti)—experts in the jus mos maiorum (traditional law), a body of oral laws and customs. 

Praetors established a working body of laws by judging whether or not singular cases were capable of being prosecuted either by the edicta, the annual pronunciation of prosecutable offense, or in extraordinary situations, additions made to the edicta. An iudex would then prescribe a remedy according to the facts of the case.

The sentences of the iudex were supposed to be simple interpretations of the traditional customs, but—apart from considering what traditional customs applied in each case—soon developed a more equitable interpretation, coherently adapting the law to newer social exigencies. The law was then adjusted with evolving institutiones (legal concepts), while remaining in the traditional mode. Praetors were replaced in the 3rd century BC by a laical body of prudentes. Admission to this body was conditional upon proof of competence or experience.

Under the Roman Empire, schools of law were created, and practice of the law became more academic. From the early Roman Empire to the 3rd century, a relevant body of literature was produced by groups of scholars, including the Proculians and Sabinians. The scientific nature of the studies was unprecedented in ancient times. 

After the 3rd century, juris prudentia became a more bureaucratic activity, with few notable authors. It was during the Eastern Roman Empire (5th century) that legal studies were once again undertaken in depth, and it is from this cultural movement that Justinian's Corpus Juris Civilis was born.

Natural law

In its general sense, natural law theory may be compared to both state-of-nature law and general law understood on the basis of being analogous to the laws of physical science. Natural law is often contrasted to positive law which asserts law as the product of human activity and human volition. 

Another approach to natural-law jurisprudence generally asserts that human law must be in response to compelling reasons for action. There are two readings of the natural-law jurisprudential stance.

1. The Strong Natural Law Thesis holds that if a human law fails to be in response to compelling reasons, then it is not properly a "law" at all. This is captured, imperfectly, in the famous maxim: lex iniusta non est lex (an unjust law is no law at all).
2. The Weak Natural Law Thesis holds that if a human law fails to be in response to compelling reasons, then it can still be called a "law", but it must be recognized as a defective law.

Notions of an objective moral order, external to human legal systems, underlie natural law. What is right or wrong can vary according to the interests one is focused on. John Finnis, the most important of modern natural barristers, has argued that the maxim "an unjust law is no law at all" is a poor guide to the classical Thomist position. Strongly related to theories of natural law are classical theories of justice, beginning in the West with Plato's Republic.

Aristotle

Aristotle, by Francesco Hayez

 

Aristotle is often said to be the father of natural law. Like his philosophical forefathers Socrates and Plato, Aristotle posited the existence of natural justice or natural right (dikaion physikon, δικαίον φυσικόν, Latin ius naturale). His association with natural law is largely due to how he was interpreted by Thomas Aquinas. This was based on Aquinas' conflation of natural law and natural right, the latter of which Aristotle posits in Book V of the Nicomachean Ethics (= Book IV of the Eudemian Ethics). Aquinas's influence was such as to affect a number of early translations of these passages, though more recent translations render them more literally.

Aristotle's theory of justice is bound up in his idea of the golden mean. Indeed, his treatment of what he calls "political justice" derives from his discussion of "the just" as a moral virtue derived as the mean between opposing vices, just like every other virtue he describes. His longest discussion of his theory of justice occurs in Nicomachean Ethics and begins by asking what sort of mean a just act is. He argues that the term "justice" actually refers to two different but related ideas: general justice and particular justice. When a person's actions toward others are completely virtuous in all matters, Aristotle calls them "just" in the sense of "general justice"; as such, this idea of justice is more or less coextensive with virtue. "Particular" or "partial justice", by contrast, is the part of "general justice" or the individual virtue that is concerned with treating others equitably.

Aristotle moves from this unqualified discussion of justice to a qualified view of political justice, by which he means something close to the subject of modern jurisprudence. Of political justice, Aristotle argues that it is partly derived from nature and partly a matter of convention. This can be taken as a statement that is similar to the views of modern natural law theorists. But it must also be remembered that Aristotle is describing a view of morality, not a system of law, and therefore his remarks as to nature are about the grounding of the morality enacted as law, not the laws themselves. 

The best evidence of Aristotle's having thought there was a natural law comes from the Rhetoric, where Aristotle notes that, aside from the "particular" laws that each people has set up for itself, there is a "common" law that is according to nature. The context of this remark, however, suggests only that Aristotle thought that it could be rhetorically advantageous to appeal to such a law, especially when the "particular" law of one's own city was adverse to the case being made, not that there actually was such a law. Aristotle, moreover, considered certain candidates for a universally valid, natural law to be wrong. Aristotle's theoretical paternity of the natural law tradition is consequently disputed.

Thomas Aquinas

Thomas Aquinas was the most influential Western medieval legal scholar

 

Thomas Aquinas (Thomas of Aquin, or Aquino, c. 1225 – 7 March 1274) was an Italian philosopher and theologian in the scholastic tradition, known as "Doctor Angelicus, Doctor Universalis". He is the foremost classical proponent of natural theology, and the father of the Thomistic school of philosophy, for a long time the primary philosophical approach of the Roman Catholic Church. The work for which he is best known is the Summa Theologica. One of the thirty-five Doctors of the Church, he is considered by many Catholics to be the Church's greatest theologian. Consequently, many institutions of learning have been named after him.

Aquinas distinguished four kinds of law: eternal, natural, divine, and human:

• Eternal law refers to divine reason, known only to God. It is God's plan for the universe. Man needs this plan, for without it he would totally lack direction.
• Natural law is the "participation" in the eternal law by rational human creatures, and is discovered by reason.
• Divine law is revealed in the scriptures and is God's positive law for mankind.
• Human law is supported by reason and enacted for the common good.

Natural law, of course, is based on "first principles":

... this is the first precept of the law, that good is to be done and promoted, and evil is to be avoided. All other precepts of the natural law are based on this ...

The desires to live and to procreate are counted by Aquinas among those basic (natural) human values on which all other human values are based.

School of Salamanca

Francisco de Vitoria was perhaps the first to develop a theory of ius gentium (the rights of peoples), and thus is an important figure in the transition to modernity. He extrapolated his ideas of legitimate sovereign power to international affairs, concluding that such affairs ought to be determined by forms respecting of the rights of all and that the common good of the world should take precedence before the good of any single state. This meant that relations between states ought to pass from being justified by force to being justified by law and justice. Some scholars have upset the standard account of the origins of International law, which emphasizes the seminal text De iure belli ac pacis by Grotius, and argued for Vitoria and, later, Suárez's importance as forerunners and, potentially, founders of the field. Others, such as Koskenniemi, have argued that none of these humanist and scholastic thinkers can be understood to have founded international law in the modern sense, instead placing its origins in the post-1870 period.

Francisco Suárez, regarded as among the greatest scholastics after Aquinas, subdivided the concept of ius gentium. Working with already well-formed categories, he carefully distinguished ius inter gentes from ius intra gentes. Ius inter gentes (which corresponds to modern international law) was something common to the majority of countries, although, being positive law, not natural law, it was not necessarily universal. On the other hand, ius intra gentes, or civil law, is specific to each nation.

Thomas Hobbes

In his treatise, Leviathan (1651), Hobbes expresses a view of natural law as a precept—or general rule, founded on reason—by which a man is forbidden to do that which is destructive to his life, to take away the means of preserving the same, or to omit that by which he thinks it may best be preserved. Hobbes was a social contractarian and believed that the law had peoples' tacit consent. He believed that society was formed from a state of nature to protect people from the state of war that would exist otherwise. According to Hobbes, without an ordered society, life is, "solitary, poor, nasty, brutish and short". It is commonly said that Hobbes's views on human nature were influenced by his times. The English Civil War and the Cromwellian dictatorship had taken place; and, in reacting to that, Hobbes felt that absolute authority vested in a monarch, whose subjects obeyed the law, was the basis of a civilized society.

Lon Fuller

Writing after World War II, Lon L. Fuller defended a secular and procedural form of natural law. He emphasised that the (natural) law must meet certain formal requirements (such as being impartial and publicly knowable). To the extent that an institutional system of social control falls short of these requirements, Fuller argued, we are less inclined to recognize it as a system of law, or to give it our respect. Thus, the law must have a morality that goes beyond the societal rules under which laws are made.

John Finnis

Sophisticated positivist and natural law theories sometimes resemble each other and may have certain points in common. Identifying a particular theorist as a positivist or a natural law theorist sometimes involves matters of emphasis and degree, and the particular influences on the theorist's work. The natural law theorists of the distant past, such as Aquinas and John Locke made no distinction between analytic and normative jurisprudence, while modern natural law theorists, such as John Finnis, who claim to be positivists, still argue that law is moral by nature. In his book Natural Law and Natural Rights (1980, 2011), John Finnis provides a restatement of natural law doctrine.

Analytic jurisprudence

Analytic, or "clarificatory", jurisprudence means taking a neutral point of view and using descriptive language when referring to various aspects of legal systems. This was a philosophical development that rejected natural law's fusing of what law is and what it ought to be. David Hume argued, in A Treatise of Human Nature, that people invariably slip from describing what the world is to asserting that we therefore ought to follow a particular course of action. But as a matter of pure logic, one cannot conclude that we ought to do something merely because something is the case. So analysing and clarifying the way the world is must be treated as a strictly separate question from normative and evaluative questions pf what ought to be done. 

The most important questions of analytic jurisprudence are: "What are laws?"; "What is the law?"; "What is the relationship between law and power/sociology?"; and "What is the relationship between law and morality?" Legal positivism is the dominant theory, although there is a growing number of critics who offer their own interpretations.

Historical school

Historical jurisprudence came to prominence during the debate on the proposed codification of German law. In his book On the Vocation of Our Age for Legislation and Jurisprudence, Friedrich Carl von Savigny argued that Germany did not have a legal language that would support codification because the traditions, customs, and beliefs of the German people did not include a belief in a code. Historicists believe that law originates with society.

Sociological jurisprudence

An effort to systematically to inform jurisprudence from sociological insights developed from the beginning of the twentieth century, as sociology began to establish itself as a distinct social science, especially in the United States and in continental Europe. In Germany, the work of the "free law" theorists (e.g. Ernst Fuchs, Hermann Kantorowicz, and Eugen Ehrlich) encouraged the use of sociological insights in the development of legal and juristic theory. The most internationally influential advocacy for a "sociological jurisprudence" occurred in the United States, where, throughout the first half of the twentieth century, Roscoe Pound, for many years the Dean of Harvard Law School, used this term to characterise his legal philosophy. In the United States, many later writers followed Pound's lead or developed distinctive approaches to sociological jurisprudence. In Australia, Julius Stone strongly defended and developed Pound's ideas. In the 1930s, a significant split between the sociological jurists and the American legal realists emerged. In the second half of the twentieth century, sociological jurisprudence as a distinct movement declined as jurisprudence came more strongly under the influence of analytical legal philosophy; but with increasing criticism of dominant orientations of legal philosophy in English-speaking countries in the present century, it has attracted renewed interest.

Legal positivism

Positivism simply means that law is something that is "posited": laws are validly made in accordance with socially accepted rules. The positivist view of law can be seen to be based on two broad principles:

Firstly, that laws may seek to enforce justice, morality, or any other normative end, but their success or failure to do so does not determine their validity. Provided a law is properly formed, in accordance with the rules recognized in the society concerned, it is a valid law, regardless of whether it is just by some other standard.

Secondly, that law is nothing more than a set of rules to provide order and governance of society.

No legal positivist, however, argues that it follows that the law is therefore to be obeyed, no matter what. This is seen as a separate question entirely.

• What the law is (lex lata) - is determined by historical social practice (resulting in rules).
• What the law ought to be (lex ferenda) - is determined by moral considerations.

Bentham and Austin

Bentham's utilitarian theories remained dominant in law until the twentieth century

One of the earliest legal positivists was Jeremy Bentham. Along with Hume, Bentham was an early and staunch supporter of the utilitarian concept, and was an avid prison reformer, advocate for democracy, and firm atheist. Bentham's views about law and jurisprudence were popularized by his student John Austin. Austin was the first chair of law at the new University of London, from 1829. Austin's utilitarian answer to "what is law?" was that law is "commands, backed by threat of sanctions, from a sovereign, to whom people have a habit of obedience". Contemporary legal positivists, H. L. A. Hart particularly, have long abandoned this view, and have criticised its oversimplification.

Hans Kelsen

Hans Kelsen is considered one of the prominent jurists of the 20th century and has been highly influential in Europe and Latin America, although less so in common-law countries. His Pure Theory of Law describes law as "binding norms", while at the same time refusing to evaluate those norms. That is, "legal science" is to be separated from "legal politics". Central to the Pure Theory of Law is the notion of a "basic norm" (Grundnorm)'—a hypothetical norm, presupposed by the jurist, from which all "lower" norms in the hierarchy of a legal system, beginning with constitutional law, are understood to derive their authority or the extent to which they are binding. Kelsen contends that the extent to which legal norms are binding, their specifically "legal" character, can be understood without tracing it ultimately to some suprahuman source such as God, personified Nature or—of great importance in his time—a personified State or Nation.

H. L. A. Hart

In the English-speaking world, the pivotal writer was H. L. A. Hart, professor of jurisprudence at Oxford University, who argued that the law should be understood as a system of social rules. Hart rejected Kelsen's views that sanctions were essential to law and that a normative social phenomenon, like law, cannot be grounded in non-normative social facts. Hart revived analytical jurisprudence as an important theoretical debate in the twentieth century, through his book The Concept of Law.

Rules, said Hart, are divided into primary rules (rules of conduct) and secondary rules (rules addressed to officials who administer primary rules). Secondary rules are divided into rules of adjudication (how to resolve legal disputes), rules of change (how laws are amended), and the rule of recognition (how laws are identified as valid). The "rule of recognition" is a customary practice of officials (especially barristers and judges) who identify certain acts and decisions as sources of law. In 1981, Neil MacCormick wrote a pivotal book on Hart (second edition published in 2008), which further refined and offered some important criticisms that led MacCormick to develop his own theory (the best example of which is his Institutions of Law, 2007). Other important critiques include those of Ronald Dworkin, John Finnis, and Joseph Raz. 

In recent years, debates on the nature of law have become increasingly fine-grained. One important debate is within legal positivism. One school is sometimes called "exclusive legal positivism" and is associated with the view that the legal validity of a norm can never depend on its moral correctness. A second school is labeled "inclusive legal positivism", a major proponent of which is Wil Waluchow, and is associated with the view that moral considerations may, but do not necessarily, determine the legal validity of a norm.

Joseph Raz

Some philosophers used to contend that positivism was the theory that held that there was "no necessary connection" between law and morality; but influential contemporary positivists—including Joseph Raz, John Gardner, and Leslie Green—reject that view. As Raz points out, it is a necessary truth that there are vices that a legal system cannot possibly have (for example, it cannot commit rape or murder). 

Joseph Raz defends the positivist outlook, but criticized Hart's "soft social thesis" approach in The Authority of Law. Raz argues that law is authority, identifiable purely through social sources, without reference to moral reasoning. Any categorization of rules beyond their role as authority is better left to sociology than to jurisprudence.

Legal realism

Oliver Wendell Holmes was a self-styled legal realist

 

Legal realism was a view popular with some Scandinavian and American writers. Skeptical in tone, it held that the law should be understood as, and would be determined by, the actual practices of courts, law offices, and police stations, rather than as the rules and doctrines set forth in statutes or learned treatises. Legal realism had some affinities with the sociology of law and sociological jurisprudence. The essential tenet of legal realism is that all law is made by human beings and, thus, is subject to human foibles, frailties, and imperfections.

It has become common today to identify Justice Oliver Wendell Holmes, Jr., as the main precursor of American Legal Realism (other influences include Roscoe Pound, Karl Llewellyn, and Justice Benjamin Cardozo). Karl Llewellyn, another founder of the U.S. legal realism movement, similarly believed that the law is little more than putty in the hands of judges who are able to shape the outcome of cases based on their personal values or policy choices. Many consider the chief inspiration for Scandinavian legal realism to be the works of Axel Hägerström. 

Despite its decline in popularity, legal realism continues to influence a wide spectrum of jurisprudential schools today, including critical legal studies, feminist legal theory, critical race theory, sociology of law, and law and economics.

Critical legal studies

Critical legal studies are a new theory of jurisprudence that has developed since the 1970s. The theory can generally be traced to American legal realism and is considered "the first movement in legal theory and legal scholarship in the United States to have espoused a committed Left political stance and perspective". It holds that the law is largely contradictory, and can be best analyzed as an expression of the policy goals of a dominant social group.

Critical rationalism

Karl Popper originated the theory of critical rationalism. According to Reinhold Zippelius many advances in law and jurisprudence take place by operations of critical rationalism. He writes

"daß die Suche nach dem Begriff des Rechts, nach seinen Bezügen zur Wirklichkeit und nach der Gerechtigkeit experimentierend voranschreitet, indem wir Problemlösungen versuchsweise entwerfen, überprüfen und verbessern" (that we empirically search for solutions to problems, which harmonize fairly with reality, by projecting, testing and improving the solutions).

Legal interpretivism

Contemporary philosopher of law Ronald Dworkin has advocated a more constructivist theory of jurisprudence that can be characterized as a middle path between natural law theories and positivist theories of general jurisprudence. In his book Law's Empire, Dworkin attacked Hart and the positivists for their refusal to treat law as a moral issue. He argued that law is an "interpretive" concept that requires barristers to find the best-fitting and most just solution to a legal dispute, given their constitutional traditions. According to him, law is not entirely based on social facts, but includes the best moral justification for the institutional facts and practices that we intuitively regard as legal. It follows from Dworkin's view that one cannot know whether a society has a legal system in force, or what any of its laws are, until one knows some truths about the moral justifications of the social and political practices of that society. It is consistent with Dworkin's view—in contrast with the views of legal positivists or legal realists—that no-one in a society may know what its laws are, because no-one may know the best moral justification for its practices.

Interpretation, according to Dworkin's "integrity theory of law", has two dimensions. To count as an interpretation, the reading of a text must meet the criterion of "fit". Of those interpretations that fit, however, Dworkin maintains that the correct interpretation is the one that portrays the practices of the community in their best light, or makes them "the best that they can be". But many writers have doubted whether there is a single best moral justification for the complex practices of any given community, and others have doubted whether, even if there is, it should be counted as part of the law of that community.

Therapeutic jurisprudence

Consequences of the operation of legal rules or legal procedures—or of the behavior of legal actors (such as lawyers and judges)—may be either beneficial (therapeutic) or harmful (anti-therapeutic) to people. Therapeutic jurisprudence ("TJ") studies law as a social force (or agent) and uses social science methods and data to study the extent to which a legal rule or practice affects the psychological well-being of the people it impacts.

Normative jurisprudence

In addition to the question, "What is law?", legal philosophy is also concerned with normative, or "evaluative" theories of law. What is the goal or purpose of law? What moral or political theories provide a foundation for the law? What is the proper function of law? What sorts of acts should be subject to punishment, and what sorts of punishment should be permitted? What is justice? What rights do we have? Is there a duty to obey the law? What value has the rule of law? Some of the different schools and leading thinkers are discussed below.

Virtue jurisprudence

Plato (left) and Aristotle (right), a detail of The School of Athens

Aretaic moral theories, such as contemporary virtue ethics, emphasize the role of character in morality. Virtue jurisprudence is the view that the laws should promote the development of virtuous character in citizens. Historically, this approach has been mainly associated with Aristotle or Thomas Aquinas. Contemporary virtue jurisprudence is inspired by philosophical work on virtue ethics.

Deontology

Deontology is the "theory of duty or moral obligation". The philosopher Immanuel Kant formulated one influential deontological theory of law. He argued that any rule we follow must be able to be universally applied, i.e. we must be willing for everyone to follow that rule. A contemporary deontological approach can be found in the work of the legal philosopher Ronald Dworkin.

Utilitarianism

Mill believed law should create happiness

Utilitarianism is the view that the laws should be crafted so as to produce the best consequences for the greatest number of people. Historically, utilitarian thinking about law has been associated with the philosopher Jeremy Bentham. John Stuart Mill was a pupil of Bentham's and was the torch bearer for utilitarian philosophy throughout the late nineteenth century. In contemporary legal theory, the utilitarian approach is frequently championed by scholars who work in the law and economics tradition.

John Rawls

John Rawls was an American philosopher; a professor of political philosophy at Harvard University; and author of A Theory of Justice (1971), Political Liberalism, Justice as Fairness: A Restatement, and The Law of Peoples. He is widely considered one of the most important English-language political philosophers of the 20th century. His theory of justice uses a method called "original position" to ask us which principles of justice we would choose to regulate the basic institutions of our society if we were behind a "veil of ignorance". Imagine we do not know who we are—our race, sex, wealth, status, class, or any distinguishing feature—so that we would not be biased in our own favour. Rawls argued from this "original position" that we would choose exactly the same political liberties for everyone, like freedom of speech, the right to vote, and so on. Also, we would choose a system where there is only inequality because that produces incentives enough for the economic well-being of all society, especially the poorest. This is Rawls's famous "difference principle". Justice is fairness, in the sense that the fairness of the original position of choice guarantees the fairness of the principles chosen in that position.

There are many other normative approaches to the philosophy of law, including critical legal studies and libertarian theories of law.