Farmer Field is concerned about his prize cow, Daisy. In fact, he is so concerned that when his dairyman tells him that Daisy is in the field, happily grazing, he says he needs to know for certain. He doesn't want merely to have a 99 percent probability that Daisy is safe, he wants to be able to say that he knows Daisy is safe.
Farmer Field goes out to the field and standing by the gate sees in the distance, behind some trees, a white and black shape that he recognizes as his favorite cow. He goes back to the dairy and tells his friend that he knows Daisy is in the field.
Yet, at this point, does Farmer Field really know it?
The dairyman says he will check too, and goes to the field. There he finds Daisy, having a nap in a hollow, behind a bush, well out of sight of the gate. He also spots a large piece of black and white paper that has got caught in a tree.
Daisy is in the field, as Farmer Field thought.
But was he right to say that he knew she was?
The philosopher, Martin Cohen, who described this scenario originally , says that in this case the farmer:
However, we might still feel that the farmer did not really know it. Herein lies the core of the problem of 'knowledge as justified true belief'.
Many or most analytic philosophers would wish to be able to hold to what is known as the JTB account of knowledge: the claim that knowledge can be conceptually analyzed as justified true belief — which is to say that the meaning of sentences such as "Smith knows that it rained today" can be given with the following set of necessary and jointly sufficient conditions:
A subject S knows that a proposition P is true if, and only if:
Gettier's paper used counterexamples (see also Thought experiment) to argue that there are cases of beliefs that are both true and justified — therefore satisfying all three conditions for knowledge on the JTB account — but that do not appear to be genuine cases of knowledge. Gettier, therefore, argued that his counterexamples show that the JTB account of knowledge is false — and thus, that a different conceptual analysis is needed to correctly track what we mean by "knowledge".
Gettier's case is based on two counterexamples to the JTB analysis. Both of them rely on the established claim (under JTB) that justification is preserved by entailment, and the further claim that such applies significantly, or can be applied there coherently to the "stipulation" attributed to Smith's putative "belief" in the case of this particular counter-example: that is, that if Smith is justified in believing P, and Smith realizes that the truth of P entails the truth of Q, then Smith would also be justified in believing Q. Gettier calls these counterexamples "Case I" and "Case II":
Again, it seems as though Luke does not "know" that Mark is in the room, even though it is claimed he has a justified true belief that Mark is in the room, but it's not nearly so clear that the perceptual belief that "Mark is in the room" was inferred from any premises at all, let alone any false ones, nor led to significant conclusions on its own; Luke didn't seem to be reasoning about anything; "Mark is in the room" seems to have been part of what he seemed to see.
To save the "no false lemmas" solution, one must logically say that Luke's inference from sensory data does not count as a justified belief unless he consciously or unconsciously considers the possibilities of deception and self-deception. A justified version of Luke's thought process, by that logic, might go like this:
And the third step counts as a false premise. But by the previous argument, this suggests we have fewer justified beliefs than we think we do.
In another example, Matthew drives through an area that appears to have many barns. In fact it contains a great many realistic barn facades, perhaps made to help shoot a Hollywood movie 'on location'. When Matthew looks at the one real barn along his route, he forms the allegedly justified true belief, 'There's a barn over there.' But if he follows the strong requirement for justified belief, then his thought process will follow the previous mentioned steps exactly. A similar process appears in Robert Heinlein's Stranger in a Strange Land as an example of "Fair Witness" behavior.
The Gettier problem is posed in terms of a problem in first-order logic, but the introduction into the discussion by Gettier of terms such as belief and knows moves the discussion into the field of epistemology. Here, the sound (believed) arguments ascribed to Smith, then need also to be valid (true) and convincing (justified) if they are to issue in real-world discussion about justified true belief. Gettier's problem has attracted a range of more sophisticated responses. The different directions that these responses have taken are constrained by the structure of Gettier's argument: if knowledge is solely justified true belief, then there cannot be any cases of justified true belief that are not also cases of knowledge; but Gettier claims that his counterexamples are cases of justified true belief without being cases of knowledge. Therefore, in this account, one is to either accept Gettier's conclusion — and elucidate a new conceptual analysis for knowledge — or else deny one of Gettier's two claims about his counterexamples (that is, either deny that Gettier cases are justified true beliefs, or else accept that Gettier cases are knowledge after all).
One response, therefore, is that in none of the above cases was the belief justified: it is impossible to justify anything which is not true. Under this interpretation the JTB definition of knowledge survives. The problem is now not to define knowledge but to define justification.
However, most contemporary epistemologists accept Gettier's conclusion. Their responses to the Gettier problem, therefore, consist of trying to find alternate analyses of knowledge. They have struggled to discover and agree upon as a beginning any single notion of truth, or belief, or justifying which is wholly and obviously accepted. Truth, belief, and justifying have yet been singly defined. Gettier, for many years a professor at University of Massachusetts Amherst later also was interested in the epistemic logic of Hintikka, a Finnish philosopher at Boston University, who published Knowledge and Belief in 1962.
James Chase contrived a counter-example to Goldman:
By the justified true belief analysis, this is knowledge. Kasim's belief is true, and justified. But according to Goldman, Kasim's belief is not appropriately causally related to Omar being dead, so it isn't knowledge.
Consider what effects that might conceivably have practical bearings you conceive the objects of your conception to have. Then, your conception of those effects is the whole of your conception of the object.
From a pragmatic viewpoint then, defining on a particular occasion whether a particular belief can rightly be said to be both true and justified is seen as no more than an exercise in pedantry, but being able to discern whether that belief led to fruitful outcomes is a fruitful enterprise.
Nozick's definition is intended to preserve Goldman's intuition that Gettier cases should be ruled out by disacknowledging "accidentally" true justified beliefs, but without risking the potentially onerous consequences of building a causal requirement into the analysis. This tactic though, invites the riposte that Nozick's account merely hides the problem and does not solve it, for it leaves open the question of why Smith would not have had his belief if it had been false. The most promising answer seems to be that it is because Smith's belief was caused by the truth of what he believes; but that puts us back in the causalist camp.
Criticisms and counter examples (notably the Grandma case) prompted a revision, which resulted in the alteration of (3) and (4) to limit themselves to the same method (i.e. vision):
That this view though remains problematical has been pointed out in a lecture by Saul Kripke. The counterexample he uses is called the Fake Barn Country example, which explains that in a certain locality are a number of fake barns or facades of barns. In the midst of these fake barns is one real barn, which is painted red. There is one piece of crucial information for this example: the fake barns cannot be painted red.
Jones is driving along the highway, looks up and happens to see the real barn, and so forms the belief
Though Jones has gotten lucky, he could have just as easily been deceived and not have known it. Therefore it doesn't fulfill premise 4, for if Jones saw a fake barn he wouldn't have any idea it was a fake barn. So this is not knowledge.
An alternate example is if Jones looks up and forms the belief
According to Nozick's view this fulfills all four premises. Therefore this is knowledge, since Jones couldn't have been wrong, since the fake barns cannot be painted red. This is a troubling account however, since it seems the first statement I see a barn can be inferred from I see a red barn, however by Nozick's view the first belief is not knowledge and the second is knowledge.
One could turn the tables on Smith and the Gettier analysis by retreating then from the strong position in stages, and holding to that weakened form which can count as superior for some cogent purpose or in an intuititive way to the Gettier analysis in the case of any particular exemplar. One would advance a series of say ten or more distinct lines of deflecting the Gettier analysis, each on linguistic, or even metaepistemological (in this case, the issue of Smith's identity) grounds, since the Gettier analysis is faultless in its logical validity.
One might respond to Gettier by finding a way to avoid his conclusion(s) in the first place. However, it can hardly be argued that knowledge is justified true belief if there are cases that are justified true belief without being knowledge; thus, those who want to avoid Gettier's conclusions have to find some way to defuse Gettier's counterexamples. In order to do so, within the parameters of the particular counter-example or exemplar, they must then either accept that
or, demonstrate a case in which it is possible to circumvent surrender to the exemplar by eliminating any necessity for it to be considered that JTB apply in just those areas which Gettier has rendered obscure, without thereby lessening the force of JTB to apply in those cases where it actually is crucial. Then though Gettier's cases stipulate that Smith has a certain belief and that his belief is true, it seems that in order to propose (1), one must argue that Gettier, (or, that is, the writer responsible for the particular form of words on this present occasion known as case (1), and who makes assertion's about Smith's "putative" beliefs), goes wrong because he has the wrong notion of justification. Such an argument often depends on an externalist account on which "justification" is understood in such a way that whether or not a belief is "justified" depends not just on the internal state of the believer, but also on how that internal state is related to the outside world. Externalist accounts typically are constructed such that Smith's putative beliefs in Case I and Case II are not really justified (even though it seems to Smith that they are), because his beliefs are not lined up with the world in the right way, or that it is possible to show that it is invalid to assert that "Smith" has any significant ''particular" belief at all, in terms of JTB or otherwise. Such accounts, of course, face the same burden as causalist responses to Gettier: they have to explain what sort of relationship between the world and the believer counts as a justificatory relationship.
Those who accept (2) are by far in the minority in Anglo-American philosophy; generally those who are willing to accept it are those who have independent reasons to say that more things count as knowledge than the intuitions that led to the JTB account would acknowledge. Chief among these are epistemic minimalists such as Crispin Sartwell, who hold that all true belief, including both Gettier's cases and lucky guesses, counts as knowledge.