Edited by John Greco (Saint Louis University)
Assistant editor: Everett Fulmer (Loyola University, New Orleans)
About this topic
Summary Skepticism involves doubt, or at least a reluctance to commit. For example, some philosophers are moral skeptics, claiming that no one can know what is right or wrong. Skepticism about the "external world" is more general, denying that there is knowledge of the world “outside our minds.”  Even more generally, some skeptics claim that there is no knowledge at all.  Philosophers have long explored reasons for and against various skeptical positions and argued about the consequences of adopting various skeptical stances.   In the ancient world, skepticism was recommended as a way of life.  The general claim was that living with an attitude of skeptical doubt is superior (morally and/or practically) to living with an attitude of dogmatic certainty.  In the modern world (i.e., the 1600s through the 1800s), skepticism was more often treated as something to be avoided, and considerable philosophical energy was put into strategies for doing so.  In contemporary philosophy, skepticism is typically framed as a theoretical problem rather than a practical one. The concern is to closely consider the best arguments for skepticism and to explore how best to respond to them.  Attempts to answer skeptical arguments have inspired philosophers to adopt substantive positions in epistemology, but also in ontology, philosophy of mind, philosophy of language, and moral philosophy.  
Key works The Oxford Handbook of Skepticism provides a comprehensive introduction to skeptical arguments and responses to skepticism.  Influential volumes include Popkin 1960Unger 1975Stroud 1984; and Williams 1991.   
Introductions Useful introductory articles include DeRose 1995; Greco 2007Pritchard 2002.
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  1. Memorial Justification.Robert Audi - 1995 - Philosophical Topics 23 (1):31-45.
  2. Articulation and Justification.Renford Bambrough - 1988 - The Monist 71 (3):311-319.
  3. Chisholm and the Foundation Theory of Justification.Emmett C. Barcalow - 1981 - Dissertation, Columbia University
    According to Roderick Chisholm, every proposition one is justified in believing is justified, at least in part, by some relation that it bears to propositions which are epistemologically privileged. There are two categories of such "basic" of self-justifying propositions--the self-presenting and the directly evident. Justification is a matter of degree, and Chisholm establishes a five-fold ranking of epistemic privilege in terms of which the two concepts of the self-presenting and the directly evident are defined and in terms of which the (...)
  4. Intellectual Assurance: Essays on Traditional Epistemic Internalism.M. Bergmann & B. Coppenger (eds.) - 2016 - Oxford University Press.
  5. Stroud, Hegel, Heidegger: A Transcendental Argument.Kim Davies - forthcoming - Brill.
    _ Source: _Page Count 25 This paper presents an original, ambitious, truth-directed transcendental argument for the existence of an ‘external world’. It begins with a double-headed starting-point: Stroud’s own remarks on the necessary conditions of language in general, and Hegel’s critique of the “fear of error.” The paper argues that the sceptical challenge requires a particular critical concept of thought as that which may diverge from reality, and that this concept is possible only through reflection on situations of error, in (...)
  6. What's an Epistemologist to Do?Aron Edidin - 1994 - American Philosophical Quarterly 31 (4):285 - 296.
  7. Zombie Philosophy.John Gibson - 2014 - In Edward P. Comentale & Aaron Jaffe (eds.), The Year's Work at the Zombie Research Center. Bloomington, IN, USA: pp. 416-436.
  8. Review of What Do Philosophers Do? Skepticism and the Practice of Philosophy BY Maddy Penelope. [REVIEW]Xingming Hu - forthcoming - Philosophical Quarterly.
    It is worth noting that Maddy oversimplifies the history of Gettierology, for a lot of epistemologists who work on the Gettier Problem do not engage in analysing the concept of knowledge.
  9. Demon Possession and Allied Themes, Being an Inductive Study of Phenomena of Our Own Times.No Authorship Indicated - 1895 - Psychological Review 2 (5):529-531.
  10. The External World and Induction.Everett J. Nelson - 1942 - Philosophy of Science 9 (3):261-267.
  11. The New Hume Debate (Review). [REVIEW]Paul Russell - 2003 - Journal of the History of Philosophy 41 (1):132-134.
  12. Epistemological Reflection on Knowledge of the External World.Review author[S.]: Barry Stroud - 1996 - Philosophy and Phenomenological Research 56 (2):345-358.
Brains in Vats
  1. Reliabilism and Brains in Vats.Jon Altschul - 2011 - Acta Analytica 26 (3):257-272.
    According to epistemic internalism, the only facts that determine the justificational status of a belief are facts about the subject’s own mental states, like beliefs and experiences. Externalists instead hold that certain external facts, such as facts about the world or the reliability of a belief-producing mechanism, affect a belief’s justificational status. Some internalists argue that considerations about evil demon victims and brains in vats provide excellent reason to reject externalism: because these subjects are placed in epistemically unfavorable settings, externalism (...)
  2. What is Realistic About Putnam's Internal Realism?David L. Anderson - 1992 - Philosophical Topics 20 (1):49-83.
    Failure to recognize the "realistic" motivations for Putnam's commitment to internal realism has led to a widely shared misunderstanding of Putnam's arguments against metaphysical realism. Realist critics of these arguments frequently offer rebuttals that fail to confront his arguments. Simply put, Putnam's arguments --the brains in a vat argument as well as the model-theoretic argument -- are "reductios" that are intended to show that "metaphysical realism itself is not sufficiently realistic". If that claim can be substantiated then Putnam can go (...)
  3. Ignorance and Knowledge: The Viability of Externalist Neo-Mooreanism as a Resonse to Radical Scepticism.John Asquith - 2017 - Dissertation, King's College London
    Here, I shall be examining the viability of a Moorean response to the Argument from Ignorance; i.e., one that tries to rebut the argument by denying its first premise that we cannot have knowledge that we are not BIVs. After first explicating the Argument from Ignorance in detail, I then go on to try and motivate this approach by critically examining two alternative approaches to dealing with radical scepticism: closure-denial, and attributer contextualism. Finding them wanting, I then turn to a (...)
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  4. An Old Problem for the New Rationalism.Yuval Avnur - 2011 - Synthese 183 (2):175-185.
  5. Putnam on Skepticism.Yemima Ben-Menahem - 2005 - In Hilary Putnam. Cambridge University Press. pp. 125--55.
  6. Can Brains in Vats Think as a Team?Hans Bernhard Schmid - 2003 - Philosophical Explorations 6 (3):201-217.
  7. A Moorean Response to Brain-in-a-Vat Scepticism.T. Black - 2002 - Australasian Journal of Philosophy 80 (2):148 – 163.
  8. A Closer Look at Closure Scepticism.Michael Blome-Tillmann - 2006 - Proceedings of the Aristotelian Society (Paperback) 106 (3):381-390.
    The most prominent arguments for scepticism in modern epistemology employ closure principles of some kind. To begin my discussion of such arguments, consider Simple Knowledge Closure (SKC): (SKC) (Kxt[p] ∧ (p → q)) → Kxt[q].1 Assuming its truth for the time being, the sceptic can use (SKC) to reason from the two assumptions that, firstly, we don’t know ¬sh and that, secondly, op entails ¬sh to the conclusion that we don’t know op, where ‘op’ and ‘sh’ are shorthand for ‘ordinary (...)
  9. Review of The Brain in a Vat, Edited by S. Goldberg. [REVIEW]Cameron Boult - forthcoming - International Journal for the Study of Skepticism.
  10. Of Brains in Vats, Whatever Brains in Vats May Be.C. Johnsen Bredo - 2003 - Philosophical Studies 112 (3):225 - 249.
    Hilary Putnam has offered two arguments to show that we cannotbe brains in a vat, and one to show that our cognitive situationcannot be fully analogous to that of brains in a vat. The latterand one of the former are irreparably flawed by misapplicationsof, or mistaken inferences from, his semantic externalism; thethird yields only a simple logical truth. The metaphysical realismthat is Putnams ultimate target is perfectly consistent withsemantic externalism.
  11. The External World.C. D. Broad - 1921 - Mind 30 (120):385-408.
  12. Proof.Jessica Brown - unknown
    Davies and Wright have recently diagnosed the felt inadequacy of Moore’s response to the sceptic in terms of a failure of transmission of warrant. They argue that warrant fails to transmit across the following key inference: I have hands, if I have hands then I am not a BIV, so I am not a BIV, on the grounds that this inference cannot be used to rationally overcome doubt about its conclusion, and cannot strengthen one’s epistemic position with respect to the (...)
  13. Debasing scepticism.A. Brueckner - 2011 - Analysis 71 (2):295-297.
    In this paper, I will clarify Jonathan Schaffer's; debasing scepticism, highlighting its logical structure. 1 In many current discussions of scepticism, its scope is limited to propositions about the external world which, if known at all, are known a posteriori. The standard sceptical set-up goes as follows. The sceptic specifies a sceptical hypothesis, or counterpossibility, that is incompatible with the external-world propositions that I claim to know. The hypothesis – e.g. that I am a brain in a vat – is (...)
  14. Klein on Closure and Skepticism.A. L. Brueckner - 2000 - Philosophical Studies 98 (2):139-151.
  15. Reply to Coffman on Closure and Skepticism.Anthony Brueckner - 2008 - Synthese 162 (2):167–171.
    E. J. Coffman defends Peter Klein’s work on epistemic closure against various objections that I raised in an earlier paper. In this paper, I respond to Coffman.
  16. Johnsen on Brains in Vats.Anthony Brueckner - 2006 - Philosophical Studies 129 (3):435-440.
    This is a response to a recent Philosophical Studies article by Bredo Johnsen, in which he makes a number of criticisms of Putnamian anti-skeptical arguments.
  17. Scepticism and the Causal Theory of Reference.Anthony Brueckner - 1995 - Philosophical Quarterly 45 (179):199-201.
  18. Ebbs on Skepticism, Objectivity and Brains in Vats.Anthony Brueckner - 1994 - Pacific Philosophical Quarterly 75:77-87.
  19. Conceiving One's Envatment While Denying Metaphysical Realism.Anthony Brueckner - 1992 - Australasian Journal of Philosophy 70 (4):469 – 474.
    J.D. Collier sees Putnam as arguing that metaphysical realism is false.' He sees the argument as proceeding from the background assumption that metaphysical realism has the consequence that truth is 'radically non-epistemic', so that 'an [epistemically] ideal theory could be radically wrong about the world' [3, p. 413]. But, according to Collier, Putnam argues that 'an ideal theory satisfying all of our methodological and theoretical constraints cannot be false' [3, p. 413]. Collier attempts to defend metaphysical realism against this Putnamian (...)
  20. If I Am a Brain in a Vat, Then I Am Not a Brain in a Vat.Anthony Brueckner - 1992 - Mind 101 (401):123-128.
    Massimo Dell'Utri (1990) provides a reconstruction of Hilary Putnam's argument (1981, chapter 1) to show that the hypothesis that we are brains in a vat is self-refuting. I will explain why the argument Dell'Utri offers us is, on the face of it, quite problematic. Then I will provide a way out of the difficulty.
  21. ``Skepticism and Epistemic Closure&Quot.Anthony Brueckner - 1985 - Philosophical Topics 13 (3):89--117.
  22. Brains in a Vat.Anthony L. Brueckner - 1986 - Journal of Philosophy 83 (3):148-167.
    In chapter 1 of Reason, Truth, and History, Hilary Putnam argues from some plausible assumptions about the nature of reference to the conclusion that it is not possible that all sentient creatures are brains in a vat. If this argument is successful, it seemingly refutes an updated form of Cartesian skepticism concerning knowledge of physical objects. In this paper, I will state what I take to be the most promising interpretation of Putnam's argument. My reconstructed argument differs from an argument (...)
  23. Losing Track of the Sceptic.Anthony L. Brueckner - 1985 - Analysis 45 (2):103 - 104.
  24. Why Nozick is a Sceptic.Anthony L. Brueckner - 1984 - Mind 93 (370):259-264.
  25. Debating Self-Knowledge.Anthony Brueckner & Gary Ebbs - 2012 - Cambridge University Press.
    Language users ordinarily suppose that they know what thoughts their own utterances express. We can call this supposed knowledge minimal self-knowledge. But what does it come to? And do we actually have it? Anti-individualism implies that the thoughts which a person's utterances express are partly determined by facts about their social and physical environments. If anti-individualism is true, then there are some apparently coherent sceptical hypotheses that conflict with our supposition that we have minimal self-knowledge. In this book, Anthony Brueckner (...)
  26. Deflationary Approaches to Scepticism.Robert Reid Buchanan - 1999 - Dissertation, Mcmaster University (Canada)
    This dissertation examines a traditional philosophical problem within a novel framework. The so-called "problem of the external world" is a problem about how knowledge, and even reasonable belief, about the world are possible, and it is best characterized as the challenge to show how and why scepticism about the external world---the absurd view that such knowledge is impossible---is incorrect. My framework for the examination of this problem involves two major elements. ;The first element involves a general characterization of the nature (...)
  27. Problems for Semantic Externalism and A Priori Refutations of Skeptical Arguments.Keith Butler - 2000 - Dialectica 54 (1):29-49.
    SummaryA familiar sort of argument for skepticism about the external world appeals to the evidential similarity between what is presumed to be the normal case and the case where one is a brain in a vat . An argument from Putnam has been taken by many to provide an a priori refutation of this sort of skeptical argument. The question I propose to address in this paper is whether Putnam's argument affords us an a priori refutation of skeptical arguments that (...)
  28. Brains in Vats and Model Theory.Tim Button - forthcoming - In Sanford Goldberg (ed.), The Brain in a Vat. Cambridge University Press.
    Hilary Putnam’s BIV argument first occurred to him when ‘thinking about a theorem in modern logic, the “Skolem–Löwenheim Theorem”’ (Putnam 1981: 7). One of my aims in this paper is to explore the connection between the argument and the Theorem. But I also want to draw some further connections. In particular, I think that Putnam’s BIV argument provides us with an impressively versatile template for dealing with sceptical challenges. Indeed, this template allows us to unify some of Putnam’s most enduring (...)
  29. The Limits of Realism.Tim Button - 2015 - Oxford University Press UK.
    Tim Button explores the relationship between minds, words, and world. He argues that the two main strands of scepticism are deeply related and can be overcome, but that there is a limit to how much we can show. We must position ourselves somewhere between internal realism and external realism, and we cannot hope to say exactly where.
  30. Why Boltzmann Brains Are Bad.Sean M. Carroll - forthcoming - In Shamik Dasgupta & Brad Weslake (eds.), Current Controversies in the Philosophy of Science. Routledge.
    Some modern cosmological models predict the appearance of Boltzmann Brains: observers who randomly fluctuate out of a thermal bath rather than naturally evolving from a low-entropy Big Bang. A theory in which most observers are of the Boltzmann Brain type is generally thought to be unacceptable, although opinions differ. I argue that such theories are indeed unacceptable: the real problem is with fluctuations into observers who are locally identical to ordinary observers, and their existence cannot be swept under the rug (...)
  31. Brains in a Vat, Language and Metalanguage.Roberto Casati & Jérôme Dokic - 1991 - Analysis 51 (2):91 - 93.
  32. Structuralism as a Response to Skepticism.David Chalmers - forthcoming - Journal of Philosophy.
  33. The Matrix as Metaphysics.David J. Chalmers - 2005 - In Christopher Grau (ed.), Philosophers Explore the Matrix. Oxford University Press. pp. 132.
    The Matrix presents a version of an old philosophical fable: the brain in a vat. A disembodied brain is floating in a vat, inside a scientist’s laboratory. The scientist has arranged that the brain will be stimulated with the same sort of inputs that a normal embodied brain receives. To do this, the brain is connected to a giant computer simulation of a world. The simulation determines which inputs the brain receives. When the brain produces outputs, these are fed back (...)
  34. Skeptical Problems, Semantical Solutions.David Christensen - 1993 - Philosophy and Phenomenological Research 53 (2):301-321.
  35. Could I Conceive Being a Brain in a Vat?John D. Collier - 1990 - Australasian Journal of Philosophy 68 (4):413 – 419.
  36. Embodiment or Envatment? Reflections on the Bodily Basis of Consciousness.Diego Cosmelli & Evan Thompson - 2013 - In J. Stewart, O. Gapenne & E Di Paolo (eds.), Enaction: Towards a New Paradigm for Cognitive Science. MIT Press.
    Suppose that a team of neurosurgeons and bioengineers were able to remove your brain from your body, suspend it in a life-sustaining vat of liquid nutrients, and connect its neurons and nerve terminals by wires to a supercomputer that would stimulate it with electrical impulses exactly like those it normally receives when embodied. According to this brain-in-a-vat thought experiment, your envatted brain and your embodied brain would have subjectively indistinguishable mental lives. For all you know—so one argument goes—you could be (...)
  37. Putnamian Anti-Envattor Ver. 3.00: New Features – Same Results.Jonas Dagys - 2010 - Problemos 77:39-48.
    The paper is devoted to a discussion and critical evaluation of antisceptical arguments in epistemology that are based on causal theory of reference, with the special focus upon the revised version of the Hilary Putnam‘s Brain-in-a-Vat argument presented by Olaf Müller. Müller claims that his argument is based on the metaphysically neutral principles of semantic externalism and disquotation, however more thorough analysis of these principles and of the possibility to use them for antisceptical purposes reveals the flaw in his argument. (...)
  38. Neither Mentioning 'Brains in a Vat' nor Mentioning Brains in a Vat Will Prove That We Are Not Brains in a Vat.Marian David - 1991 - Philosophy and Phenomenological Research 51 (4):891-896.
    In Reason, Truth, and History Hilary Putnam has presented an anti-skeptical argument purporting to prove that we are not brains in a vat. How exactly the argument goes is somewhat controversial. A number of competing "recon¬structions" have been proposed. They suffer from a defect which they share with what seems to be Putnam's own version of the argument. In this paper, I examine a very simple and rather natural reconstruction of the argument, one that does not employ any premises in (...)
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