Ayer, A.J (1965) "The Problem of Knowledge" Ch. 1. Section V, pp. 28-34, New York: MacMillan. (Original work published in 1956)
Ayer’s version of Kim-on-traditional-analysis-of-knowledge = A person S knows that P, for some proposition P, if and only if:
- P is true
- S is sure that P
- S has the right to be sure that P
Ayer’s refinement to the analysis of knowledge
The belief condition that “S should believe that P” in the traditional analysis is replaced with the condition that “S must be sure that P”.
- By doing this, Ayer is emphasizing that not all beliefs are equally strong, and that knowledge requires a belief with a high degree of confidence or conviction.
- To know something, it’s not enough to believe it, you must be sure of it.
The justification condition is understood in terms of “the right to be sure”
- it now matches the idea of being sure as the belief condition
- “the right to be sure” means that the confidence is supported by adequate justification, by evidence, reasoning, or experience that makes the belief reasonable
Kim-on-traditional-analysis-of-knowledge Knowledge = True belief + Justification.
Ayer’s reformulation preserves the same idea but adjusts the language: Knowledge = True belief + justified sureness
Ayer’s version includes subjective certainty (the belief condition) and objective entitlement (justification condition).
standards associated with “the right to be sure”
For empirical statements, we know things by our sense perceptions, by making reference to testimony (what someone else has perceived), by memory, etc. According to Ayer, our “right to be sure” comes from these ordinary common-sense sources of knowledge, grounding justification in familiar human abilities and sources of evidence.
Ayer observes that in everyday life, people are generally competent judges of whether someone is justified (has the “right to be sure”) in believing something. E.g there would be doubt that someone with a poor memory remembering a detail from years ago has the right to be sure. However, Ayer argues that deciding on general standards would be extremely complicated as it is on a case-by-case basis
“… to say in general how strong [the justification] has to be would require us to draw up a list of conditions under which perception, or memory, or testimony, or other forms of evidence are reliable. And this would be a very complicated matter, if indeed it could be done at all.”
Our judgments about who knows depend on context, evidence, and human reliability — things too variable to capture in a rigid philosophical rule. An analysis of knowledge is not necessarily going to give us the answers to all the issues in our theory of knowledge.