21st-century philosophers - Karel Lambert ,Stephen Laurence, Michèle Le Dœuff ,Robin LePoidevin ,Jonathan Lear ,Gary Legenhausen ,Brian Leiter ,James G. Lennox, S. Matthew Liao ,Alphonso Lingis, Peter LiptonHelen Longino,Kuno Lorenz,John Randolph Lucas,Peter Ludlow,Max Lüscher,William Lycan

Karel Lambert (born 1928) is a philosopher and logician at the University of California, Irvine and the University of Salzburg. He has written extensively on the subject of free logic, a term which he coined.
Lambert's Law
Lambert's Law is the adjustment of a given standard predicate logic such as to relieve it of existential assumptions, and so make it a free logic. Taking Bertrand Russell's predicate logic in his Principia Mathematica as standard, one replaces universal instantiation, , with universal specification . Thus universal statements, like "All men are mortal," or "Everything is a unicorn," do not presuppose that there are men or that there is anything. These would be symbolized, with the appropriate predicates, as and , which in Principia Mathematica entail and , but not in free logic. The truth of these last statements, when used in a free logic, depend on the domain of quantification, which may be the null set.

Stephen Laurence is a scientist and philosopher, currently at the University of Sheffield, whose primary areas of research interest are the philosophy of mind, the philosophy of language, and cognitive science.
He is Director of the Innateness and the Structure of the Mind Project, an interdisciplinary inquiry into nativist theorizing funded by the Arts & Humanities Research Council.
He is also Co-Director of the Hang Seng Centre for Cognitive Studies.

Michèle Le Dœuff (1948- ) is a French feminist philosopher and playwright. One of the most important contemporary feminist philosophers, Le Dœuff's work is highly critical of the philosophical tradition and its treatment of women. Le Dœuff’s ideas are driven by her intense philosophical and literary analysis of English empiricist philosophy, especially of Francis Bacon. This historicism places her in a rare position within continental philosophy. A capable critic of English empiricism, the analytical and the continental traditions of philosophy, Le Dœuff is concerned in her work to highlight the subtle fundamental ways in which both traditional philosophy and scientific thinking imagines a world in which women are inferior and incapable of rational and analytical thought. In books such as Recherches sur l'Imaginaire Philosophique (trans. The Philosophical Imaginary), now a classic text in feminist philosophy, Le Doeuff analyses a markedly misogynist relation to otherness within philosophy that has had a widespread and mythical dissemination: the philosophical imaginary that is an inescapeably irrational and uncritical foundation for knowledge in the writings of canonical philosophers.

Robin Le Poidevin (born 1962) is professor of metaphysics at the University of Leeds whose interests include the nature and experience of time,agnosticism, and philosophy of religion.He joined the department of philosophy at Leeds in 1989 having completed postgraduate studies at both Oxford and Cambridge, obtaining his MA from the former and his Ph.D from the latter.He is also the current president of The British Society for the Philosophy of Religion.

Jonathan Lear is the John U. Nef Distinguished Service Professor in the Committee on Social Thought and professor of philosophy at the University of Chicago.
The Committee on Social Thought is one of several PhD-granting committees at the University of Chicago. It was started in 1941 by historian John Ulric Nef along with economist Frank Knight, anthropologist Robert Redfield, and University President Robert Maynard Hutchins.

Gary Carl (Muhammad) Legenhausen (born 1953, New York) is an American philosopher who teaches at the Imam Khomeini Education and Research Institute, which is directed by Mohammad Taghi Mesbah Yazdi.
He converted to Islam in 1983. He wrote a book entitled Islam and Religious Pluralism in which he advocates "non-reductive religious pluralism". He has been an advocate of interfaith dialogue, and serves on the advisory board of the Society for Religious Studies in Qom. He holds a Ph.D. in philosophy from Rice University (1983).
He taught philosophy of religion, ethics and epistemology at the Islamic Iranian Academy of Philosophy from 1990 until 1994. Since 1996, he has been studying Islam and teaching Western philosophy and Christianity at the Imam Khomeini Education and Research Institute in Iran. He is also a founding member of the advisory board of the Shi`ite Studies Center in Qom, and serves on the scientific board of the Human Rights Center of Mofid University, Qom.
Brought up as a Catholic, he abandoned religion shortly after beginning his academic studies at the State University of New York at Albany. In 1979, he became acquainted with Islam through Muslim students at Texas Southern University, where he taught from 1979 to 1989.

Ayatollah Mohammad Taghi Mesbah Yazdi (Persian: محمد تقی مصباح‌یزدی) (born 31 January 1934 in Yazd) is a hardline Iranian Twelver Shi'i cleric and politician who is widely seen as Iranian President Mahmoud Ahmadinejad's spiritual advisor. He is also a member of Iran's Assembly of Experts.

Brian Leiter (born 1963) is an American philosopher and legal scholar who is currently John Wilson Professor of Law at the University of Chicago, and founder and Director of Chicago's new Center for Law, Philosophy, and Human Values and the editor of the Philosophical Gourmet Report. He taught from 1995 to 2008 at the University of Texas at Austin. Before that he taught for two years in the law school at the University of San Diego, and was also a visiting assistant professor of philosophy at the University of California, San Diego. He earned his Bachelor of Arts in philosophy from Princeton University and both his J.D. and Ph.D. (in philosophy) from the University of Michigan.
At Texas, Leiter was Founder and Director of the Law and Philosophy Program. He was also the youngest chair-holder in the history of the law school at Texas. He has been a visiting professor at Yale Law School, University College London, and University of Chicago Law School and will be a visiting professor of philosophy at Oxford University in 2011-12. He edited the journal Legal Theory for seven years and is also editor of the Routledge Philosophers, a new series of introductions to major philosophers, and (with Leslie Green) Oxford Studies in the Philosophy of Law. He gave the 'Or 'Emet Lecture at Osgoode Hall School of Law at York University, Toronto in 2006, and the Fresco Lectures at the University of Genoa and the Dunbar Lecture in Law and Philosophy at the University of Mississippi in 2008.
Leiter's scholarly writings have been in two main areas: legal philosophy and Continental philosophy. Philosophical naturalism has been an abiding theme in both contexts. In legal philosophy, he has offered a reinterpretation of the American Legal Realists as prescient philosophical naturalists and a general defense of what he calls "naturalized jurisprudence." This work is reflected in his book Naturalizing Jurisprudence: Essays on American Legal Realism and Naturalism in Legal Philosophy (Oxford University Press, 2007). In his writing on German philosophy, Leiter defends a reading of Nietzsche as a philosophical naturalist, most notably in Nietzsche on Morality (London: Routledge, 2002) and in subsequent papers, including one with Joshua Knobe on "The Case for Nietzschean Moral Psychology" in Nietzsche and Morality (Oxford University Press, 2007). He has also published work on meta-ethics, social epistemology, the law of evidence, and on philosophers such as Marx, Heidegger, and Dworkin.
His other publications include several dozen articles and several edited collections. These include Nietzsche (Oxford Readings in Philosophy, 2001) (with John Richardson), Objectivity in Law and Morals (Cambridge: Cambridge University Press, 2001), The Future for Philosophy (Oxford: Clarendon Press, 2004), and Nietzsche and Morality (Oxford University Press, 2007) (with Neil Sinhababu). His characterization of the contemporary philosophical scene as divided between "naturalists" and "quietists" was endorsed by Richard Rorty in an article in Rorty's final collection of papers, though Rorty sides with the quietists.
Some of Leiter's articles include "Determinacy, Objectivity, and Authority" (University of Pennsylvania Law Review) (co-authored with Jules Coleman), "Rethinking Legal Realism: Toward a Naturalized Jurisprudence" (Texas Law Review), "Nietzsche and the Morality Critics" (Ethics), "Legal Realism and Legal Positivism Reconsidered" (Ethics), "Naturalized Epistemology and the Law of Evidence" (Virginia Law Review) (co-authored with Ronald Allen), "Beyond the Hart/Dworkin Debate: The Methodology Problem in Jurisprudence" (American Journal of Jurisprudence), and "Moral Facts and Best Explanations" (Social Philosophy & Policy).

James G. Lennox (born January 11, 1948) is a professor in the Department of History and Philosophy of Science at the University of Pittsburgh. An Objectivist philosopher, he is a member of the Ayn Rand Society, affiliated with the American Philosophical Association, Eastern Division. His areas of research include Ancient Greek philosophy, science and medicine, and Charles Darwin.

S. Matthew Liao (born 1972) is a philosopher known for his work on defending the right of children to be loved.He obtained his D.Phil. in philosophy from Oxford University (2001) and graduated magna cum laude with an A.B. from Princeton University (1994).
Liao is currently an Associate Professor in the Center for Bioethics with an affiliation in the Department of Philosophy at New York University.
In 2006, Liao was appointed Deputy Director and Senior Research Fellow of the Program on the Ethics of the New Biosciences in the Faculty of Philosophy/James Martin 21st Century School at Oxford University.
Liao was the inaugural Harold T. Shapiro Research Fellow at the University Center for Human Values at Princeton University (2003-2004), and a Greenwall Research Fellow at Johns Hopkins University and a Visiting Researcher at the Kennedy Institute of Ethics at Georgetown University (2004-2006).
In May 2007, Liao founded Ethics Etc, a group blog for discussing contemporary philosophical issues in ethics and related areas.
Liao is interested in a wide range of philosophical issues in ethics, moral epistemology, metaphysics, moral psychology, and bioethics, and has published widely in peer-reviewed, academic journals such as Philosophical Studies, The Monist, Utilitas, Journal of Value Inquiry, Journal of Political Philosophy, Journal of Moral Philosophy, Journal of Applied Philosophy, Journal of Medical Ethics, American Journal of Bioethics, the Hastings Center Report, and Theoretical Medicine and Bioethics. He is currently on the Editorial Board at the American Journal of Bioethics.

Alphonso Lingis (born November 23, 1933 in Crete, Illinois) is an American philosopher, writer and translator, currently Professor Emeritus of Philosophy at Pennsylvania State University. His areas of specialization include phenomenology, existentialism, modern philosophy, and ethics.

Peter Lipton (October 9, 1954 – November 25, 2007) was the Hans Rausing Professor and Head of the Department of History and Philosophy of Science at Cambridge University, and a fellow of King's College, until his unexpected death in November 2007. According to his obituary on the Cambridge web site, he was "recognized as one of the leading philosophers of science and epistemologists in the world."

Helen E. Longino (born 13 July 1944) is an American philosopher of science who has argued influentially for the significance of values and social interactions to scientific inquiry.
In her first book, Science as Social Knowledge (1990), Longino argued for the relevance of social values, or values which are part of the human context of science, to the justification of scientific knowledge as objective. She argues that observations and data of the sort taken by scientists are not by themselves evidence for or against any particular hypotheses. Rather, the relevance of any particular data for any given hypothesis is decided by human beliefs and assumptions about what kinds of data can support what kinds of hypotheses. Moreover, even when the relevance of evidence is decided, there remains a logical gap between evidence and full justification of interesting scientific theories (the traditional philosophical problem of underdetermination of theories). This gap, too, must be bridged by beliefs and assumptions about legitimate reasoning in order for evidence to help us decide which hypotheses to accept as true.
Fortunately, the use of diverse perspectives to criticize hypotheses can turn some of those hypotheses into scientific knowledge. Hypotheses become knowledge when they are subjected to scrutiny from diverse perspectives, especially by those with diverse beliefs and values. In contrast to those philosophers who would point to the two evidential gaps above to argue that science is not objective therefore, Longino argues that scrutiny by those with diverse values can instead support the objectivity of science. Accordingly, our values which do not immediately seem to have anything to do with science are crucial to the objectivity of pieces of scientific knowledge, and science can be objective precisely because it is not value-free.
Longino's more recent book The Fate of Knowledge (2002) explored the critique of science and philosophy of science from sociology of science.
Though her work on the nature of scientific knowledge is broadly feminist in the sense that it argues for the value of contributions by diverse people (and accordingly the value of the contributions of women) to science, some of Longino's other work has been more explicitly feminist and concerned with women. She has written about the role of women in science and is a central figure in feminist epistemology and social epistemology. Beyond the study of knowledge, her writing has included the analysis of the nature of pornography and the circumstances under which it is morally problematic.

Kuno Lorenz (born September 17, 1932 in Vachdorf, Thüringen) is a German philosopher. He developed a philosophy of dialogue, in connection with the pragmatic theory of action of the Erlangen constructivist school. Lorenz is married to the literary scholar Karin Lorenz-Lindemann.
Lorenz developed (along with Paul Lorenzen) an approach to arithmetic and logic as dialogue games. In dialogical logic, tree calculations (generally, of Gentzen type calculus) are written upside down, so that the initial assertion of a proponent stays above and is defended against an opponent as in a game. This is a linguistically more congenial approach to logic which is more suitable as a model for argumentation than the formal derivation in a calculus or truth tables. Lorenz presented for the first time a simple demonstration of Gentzen's consistency proof on this game-theoretic basis. If one regards logic and mathematics in this way as a game, an intuitionist approach becomes a more plausible option.

John Randolph Lucas FBA (born 18 June 1929) is a British philosopher.
Free will
Lucas (1961) began a lengthy and heated debate over the implications of Gödel's incompleteness theorems for the anthropic mechanism thesis, by arguing that:
Determinism ↔ For any human h there exists at least one (deterministic) logical system L(h) which reliably predicts h's actions in all circumstances.
For any logical system L a sufficiently skilled mathematical logician (equipped with a sufficiently powerful computer if necessary) can construct some statements T(L) which are true but unprovable in L. (This follows from Gödel's first theorem.)
If a human m is a sufficiently skillful mathematical logician (equipped with a sufficiently powerful computer if necessary) then if m is given L(m), he or she can construct T(L(m)) and
Determine that they are true--which L(m) cannot do.
Hence L(m) does not reliably predict m's actions in all circumstances.
Hence m has free will.
It is implausible that the qualitative difference between mathematical logicians and the rest of the population is such that the former have free will and the latter do not.
His argument was strengthened by the discovery by Hava Siegelmann in the 1990s that sufficiently complex analog recurrent neural networks were not Turing Machines.

Space, time and causality
Lucas wrote several books on the philosophy of science and space-time (see below). In A treatise on time and space he introduced a transcendental derivation of the Lorenz Transformations based on Red and Blue exchanging messages (in Russian and Greek respectively) from their respective frames of reference which demonstrates how these can be derived from a minimal set of philosophical assumptions.
In The Future Lucas gives a detailed analysis of tenses and time, arguing that "the Block universe gives a deeply inadequate view of time. It fails to account for the passage of time, the pre-eminence of the present, the directedness of time and the difference between the future and the past" and in favour of a tree structure in which there is only one past or present (at any given point in spacetime) but a large number of possible futures. "We are by our own decisions in the face of other men's actions and chance circumstances weaving the web of history on the loom of natural necessity".

Peter Ludlow (January 16, 1957), who also writes under the name Urizenus Sklar, is a professor of philosophy at Northwestern University. Before moving to Northwestern, Ludlow taught at University of Toronto, the University of Michigan, and the State University of New York at Stony Brook. He has done much interdisciplinary work on the interface of linguistics and philosophy—in particular on the philosophical foundations of Noam Chomsky's theory of generative linguistics and on the foundations of the theory of meaning in linguistic semantics. He has worked on the application of analytic philosophy of language to topics in epistemology, metaphysics, and logic, among other areas.
Ludlow has also established a research program outside of philosophy and linguistics. Here, his research areas include conceptual issues in cyberspace, particularly questions about cyber-rights and the emergence of laws and governance structures in and for virtual communities. MTV.com has described Ludlow as one of the 10 most influential video game players of all time, in part due to his role in showing how video game companies can be challenged as part of the gameplay. In recent years Ludlow has written nonacademic essays on hacktivist culture and related phenomena such as Wikileaks.

Max Lüscher (born 9 September 1923, Basel, Switzerland) is a Swiss psychotherapist. He's known for inventing the Lüscher color test, a tool for measuring the person's psychophysical state based on his or her color preferences. Besides research, teaching and practicing psychotherapy in Basel, Lüscher worked for international companies, amongst other things giving color advice. His book "The Lüscher Test" has been translated into more than 30 languages.

The Lüscher color test is a psychological test invented by Dr. Max Lüscher in Basel, Switzerland. Max Lüscher believed that sensory perception of color is objective and universally shared by all, but that color preferences are subjective, and that this distinction allows subjective states to be objectively measured by using test colors.
Lüscher believed that because the color selections are guided in an unconscious manner, they reveal the person as they really are, not they perceive themselves or would like to be perceived.
The results of the Lüscher-Color-Diagnostic contain indications pertaining to personal assessment and special, professional recommendations as to how psychological stress and the resulting physical symptoms can be avoided. It also offers additional information for verbal and homeopathic therapy.
Proponents of the test claim this method allows a rapid and deep personality analysis from only this color ranking information.
A 1984 comparison of the Lüscher color test and the Minnesota Multiphasic Personality Inventory found little agreement between the two tests, prompting the authors to urge cautious use of the former. However, further in depth study other than the MMPI would be required before Lüscher's processes are totally disregarded.

William G. Lycan (b. September 26, 1945, Milwaukee, Wisconsin) is a noted American philosopher teaching at the University of North Carolina at Chapel Hill,where he is the William Rand Kenan, Jr. Distinguished Professor. He won the Class of 2001 Outstanding Faculty Award (in 2001) and a Distinguished Teaching Award for Post-Baccalaureate Instruction in 2002. Before moving to UNC in 1982, Lycan taught for several years at Ohio State University.
His principal interests include philosophy of mind, philosophy of language, philosophy of linguistics, epistemology, and metaphysics. The author of eight books and over 150 articles (and over 20 reviews) Lycan is an advocate of the version of functionalism, known as homuncular functionalism. He is also an outspoken critic of epistemic minimalism.
Along with Robert Adams, Lycan considers David Kellogg Lewis's notion of possible worlds to be metaphysically extravagant and suggests in its place an actualist interpretation of possible worlds as consistent, maximally complete sets of descriptions or propositions about the world, so that a "possible world" is conceived of as a complete description (i.e. a set of maximally consistent set of propositions) of a way the world could be – rather than a world which is that way.