How to get Certain Knowledge from Fallible Justification

Jennifer Lackey, Peter D. Klein

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Real knowledge, as I use the term, is the most highly prized form of true belief sought by an epistemic agent. This paper argues that defeasible infinitism provides a good way to characterize real knowledge and it shows how real knowledge can arise from fallible justification. Then, I argue that there are two ways of interpreting Ernest Sosa's account of real knowledge as belief that is aptly formed and capable of being fully defended. On the one hand, if beliefs are aptly formed only if they have a specific causal etiology, namely that they are efficiently caused fully or partially by virtuous characteristics of the epistemic agent, then Sosa's account falls prey to what I call the problem of the Hazard of Empirical Disconfirmation (HED). The HED problem applies to all forms of causal accounts of real knowledge and is simply that as we gain more empirical knowledge about the causal origins of our true beliefs that are the most highly prized we will discover that they do not always (or even hardly ever) satisfy the required efficient causal constraints. Bluntly put, having sufficiently good reasons for our beliefs might not require that the beliefs have the requisite efficient causal etiology. On the other hand, there is a way of interpreting Sosa's views that does not include an efficient causal prerequisite. That interpretation makes Sosa's account of real knowledge almost identical to defeasible infinitism but expressed in an alternate vocabulary. Such a view is not subject to the HED problem and it can solve the deep problem in epistemology, namely how to get epistemically certain (as opposed to psychologically certain) knowledge from fallible justification.

Original languageEnglish (US)
Pages (from-to)395-412
Number of pages18
Issue number4
StatePublished - Dec 1 2019
Externally publishedYes


  • Sosa
  • apt belief
  • certainty
  • defeasibility
  • efficient causation
  • epistemology
  • infinitism
  • justification
  • material causation
  • real knowledge
  • virtue epistemology

ASJC Scopus subject areas

  • History and Philosophy of Science


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