A or B gets a job. You know A has a coin in his pocket. C tells you that A will get the job. You therefore have the jtb that the person who gets the job has a coin in his pocket. However, it turns out that B gets the job, and coincidentally B also has a coin in his pocket.

How is this a gettier case? He was never justified since there’s always the possibility that what anyone tells you is a lie.

2 Answers 2


Justified is the most contentious word in the JTB account of knowledge, usually it can be understood as if one has strong evidence about a proposition then one is justified to believe in it. Its wikipedea reference also says the same criterion as referenced here:

Suppose that Smith and Jones have applied for a certain job. And suppose that Smith has strong evidence for the following conjunctive proposition: (d) Jones is the man who will get the job, and Jones has ten coins in his pocket. Smith's evidence for (d) might be that the president of the company assured him that Jones would, in the end, be selected and that he, Smith, had counted the coins in Jones's pocket ten minutes ago. Proposition (d) entails: (e) The man who will get the job has ten coins in his pocket.

So in the Gettier's case above the evidence that the president of the company assured him that Jones would get the job is commonly regarded as strong evidence. Of course in reality for most real-life or scientific propositions we need much more such evidences so such edge case is very unlikely to occur. Indeed, one criticism of Gettier case voiced such insufficient evidence in the same reference like you:

Affirmations of the JTB account: This response affirms the JTB account of knowledge, but rejects Gettier cases. Typically, the proponent of this response rejects Gettier cases because, they say, Gettier cases involve insufficient levels of justification. Knowledge actually requires higher levels of justification than Gettier cases involve.

Of course there're several other approaches in the same reference to solve Gettier problem and acknowledge JTB issue to perfectly define knowledge.


What you are suggesting is the solution to Gettier Problems called the Infallibility Proposal:

Thus, for instance, an infallibilist about knowledge might claim that because (in Case I) Smith’s justification provided only fallible support for his belief b [that a person with coins in their pocket will be hired], this justification was always leaving open the possibility of that belief being mistaken — and that this is why the belief is not knowledge.

The main issue with this solution is that is that is implies an form of extreme form of skepticism. As proven by Karl Popper, the probability of a belief being correct due to observations must be on the interval [0, 1). In other words, science can never justify beyond all possible doubt that a belief is true. Combine this with the Infallibility Proposal and you reach the conclusion that we can never know anything about the physical world. Although that is a valid position to take, not many people are willing to do so.

  • There are beliefs that are always uncertain. Unless you could read someone’s mind, you’ll never know if the person is lying or telling the truth about anything you haven’t witnessed. Unless you observed the whole earth, you couldn’t be assured there isn’t a white swan out there. Both these are cases of by definition speculative beliefs. Jun 14, 2021 at 9:50
  • So what you’re saying is that if we should be consistently critical of the certititude of our beliefs, then we should follow Descartes and throw away all sensory beliefs as unreliable? Jun 14, 2021 at 9:54
  • I am saying two things. First, when you claimed that the justification for knowledge must be strong enough that there is no possibility that the belief is wrong, you are claiming the Infallibility Proposal solution to Gettier Problems. Second, the reason the Infallibility Proposal is not generally accepted is that it disqualifies science as a method for gaining knowledge. I am not saying anything regarding my personal views on Gettier Problems.
    – E Tam
    Jun 15, 2021 at 0:28

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