In This Article Expand or collapse the "in this article" section Sensitivity Principle in Epistemology

  • Introduction
  • General Overviews
  • Monographs
  • Anthologies
  • Further Developments and Applications

Philosophy Sensitivity Principle in Epistemology
Guido Melchior
  • LAST REVIEWED: 22 April 2020
  • LAST MODIFIED: 22 April 2020
  • DOI: 10.1093/obo/9780195396577-0404


Sensitivity is a modal epistemic principle. Modal knowledge accounts are externalist in nature and claim that the knowledge yielding connection between a true belief and the truthmaker must be spelled out in modal terms. The sensitivity condition was introduced by Robert Nozick. He suggests that if S knows that p, then S’s belief that p tracks truth. Nozick argues that this truth-tracking relation can be captured by subjunctive conditionals. As a first approximation, he provides the following modal analysis of knowledge: S knows that p iff (1) p is true; (2) S believes that p; (3) if p were false, S wouldn’t believe that p and (4) if p were true, S would believe that p. The dominant terminology in the literature, also adopted here, is to call condition (3) the sensitivity condition and condition (4) the adherence condition. The sensitivity condition is intuitively appealing since it states that a subject does not know that p if she would believe that p even if p were false. Nozick used the sensitivity condition to accomplish two major tasks. First, he provided a solution to the Gettier problem by arguing that in Gettier cases subjects do not know since the sensitivity condition is violated. Second, he presented a controversial solution to the skeptical problem according to which we have external world knowledge but do not know that the skeptical hypothesis is false. This solution is available because sensitivity is not closed under known entailment. Quickly, criticism of the sensitivity condition emerged. First, most epistemologists regarded the price of abandoning knowledge closure as a price too high to pay. Second, it was noted that sensitivity leads to the counterintuitive consequence of precluding us from inductive knowledge since induction typically yields insensitive beliefs. The most dominant reaction to these problems was to replace sensitivity by the modal principle of safety, nowadays the most popular modal principle. However, sensitivity is not only important as a starting point of modal epistemology. Because of its intuitive attractiveness, many authors aimed at refining the original sensitivity account in order to avoid well-known problems. This has led to a second wave of sensitivity accounts. As of today, various sensitivity-based theories are on the market, including accounts that avoid closure failure, probabilistic interpretations of sensitivity and adherence, and contextualist approaches. There is thus a vivid and ongoing debate about the sensitivity principle in epistemology.

General Overviews

There is still no stand-alone overview on the sensitivity principle, though useful overviews can be found as parts of publications that develop a particular theory of sensitivity or that focus on sensitivity and safety. Becker 2007 thoroughly discusses the sensitivity principle and rival externalist accounts, such as process reliabilism and safety. Melchior 2019, chapter 2, provides a general overview of the sensitivity principle, the most influential objections, various alternative versions, and rival accounts. Pritchard 2009 is an introductory textbook on epistemology with a strong focus on modal epistemology. Pritchard 2008 contains an overview of modal responses to the skeptical challenge, including sensitivity and safety. Becker 2018 provides a systematic overview of sensitivity responses to the Gettier problem. Rabinowitz 2016 is an encyclopedia entry on safety. Weisberg 2012 provides an overview of solutions to the bootstrapping problem, which include sensitivity-like accounts.

  • Becker, Kelly. Epistemology Modalized. New York and London: Routledge, 2007.

    Contains an overview of sensitivity and of its rival accounts, namely process reliabilism and safety.

  • Becker, Kelly. “The Sensitivity Response to the Gettier Problem.” In The Gettier Problem. Edited by Stephen Hetherington, 108–124. Cambridge, UK: Cambridge University Press, 2018.

    Discusses and critically evaluates sensitivity-based solutions to the Gettier problem.

  • Melchior, Guido. Knowing and Checking: An Epistemological Investigation. New York and London: Routledge, 2019.

    DOI: 10.4324/9780429030239

    Chapter 2 of this book contains an overview of sensitivity, the most influential variants, the well-known problems, and a presentation of alternative accounts and their problems, in particular safety.

  • Pritchard, Duncan. “Sensitivity, Safety, and Anti-luck Epistemology.” In The Oxford Handbook of Skepticism. Edited by John Greco, 437–455. Oxford: Oxford University Press, 2008.

    Contains an overview of sensitivity theories and safety theories and their takes on skeptical problems and discusses problems for these accounts.

  • Pritchard, Duncan. Knowledge. London: Palgrave Macmillan, 2009.

    Introductory textbook into epistemology with chapters on safety and anti-luck epistemology that also discusses sensitivity and its problems.

  • Rabinowitz, Dani. “The Safety Condition for Knowledge.” In Internet Encyclopedia of Philosophy, Edited by James Fieser and Bradly Dowden, 2016.

    Lexicon entry on the safety principle that also compares this principle to sensitivity.

  • Weisberg, Jonathan. “The Bootstrapping Problem.” Philosophy Compass 7.9 (2012): 597–610.

    DOI: 10.1111/j.1747-9991.2012.00504.x

    Overview article on bootstrapping that labels sensitivity-like solutions to the bootstrapping problem as the no risk, no gain diagnosis.

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