The Gettier problem, in the field of epistemology, is a landmark
philosophical problem with our understanding of knowledge. Attributed
to American philosopher Edmund Gettier, Gettier-type counterexamples
(called "Gettier-cases") challenged the long-held justified true
belief (or JTB) account of knowledge. On the JTB account, knowledge is
equivalent to justified true belief, and if all three conditions
(justification, truth, and belief) are met of a given claim, then we
have knowledge of that proposition. In his three-page 1963 paper,
titled "Is Justified True
3.1 Case I 3.2 Case II
4 False premises 5 More general Gettier-style problems 6 Constructing arbitrary Gettier problems 7 Responses to Gettier
7.1 Fourth condition (JTB+G) approaches
7.1.1 Goldman's causal theory 7.1.2 Lehrer–Paxson's defeasibility condition 7.1.3 Pragmatism
7.2 Revisions of JTB approaches
7.2.1 Fred Dretske's conclusive reasons and Robert Nozick's truth-tracking 7.2.2 Richard Kirkham's skepticism
7.3 Attempts to dissolve the problem 7.4 Experimental research
8 Notes 9 References 10 External links
The question of what constitutes "knowledge" is as old as philosophy
itself. Its earliest instances are found in Plato's dialogues, notably
According to the inherited lore of the epistemological tribe, the JTB [justified true belief] account enjoyed the status of epistemological orthodoxy until 1963, when it was shattered by Edmund Gettier... Of course, there is an interesting historical irony here: it isn't easy to find many really explicit statements of a JTB analysis of knowledge prior to Gettier. It is almost as if a distinguished critic created a tradition in the very act of destroying it.
Despite this, Plantinga does accept that some philosophers before
Gettier have advanced a JTB account of knowledge, specifically C. I.
Lewis and A. J. Ayer.
A subject S knows that a proposition P is true if and only if:
P is true, and S believes that P is true, and S is justified in believing that P is true
This account of knowledge is what Gettier subjected to criticism. Gettier's two original counterexamples 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. Therefore, Gettier argued, 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. Each relies on two claims. Firstly, that justification is preserved by entailment, and secondly that this applies coherently to Smith's putative "belief". 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": Case I
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.
Let us suppose that Smith sees the entailment from (d) to (e), and accepts (e) on the grounds of (d), for which he has strong evidence. In this case, Smith is clearly justified in believing that (e) is true.
But imagine, further, that unknown to Smith, he himself, not Jones, will get the job. And, also, unknown to Smith, he himself has ten coins in his pocket. Proposition (e) is the true, though proposition (d), from which Smith inferred (e), is false. In our example, then, all of the following are true: (i) (e) is true, (ii) Smith believes that (e) is true, and (iii) Smith is justified in believing that (e) is true. But it is equally clear that Smith does not know that (e) is true; for (e) is true in virtue of the number of coins in Smith's pocket, while Smith does not know how many coins are in Smith's pocket, and bases his belief in (e) on a count of the coins in Jones's pocket, whom he falsely believes to be the man who will get the job.
Smith, it is claimed by the hidden interlocutor, has a justified belief that "Jones owns a Ford". Smith therefore (justifiably) concludes (by the rule of disjunction introduction) that "Jones owns a Ford, or Brown is in Barcelona", even though Smith has no knowledge whatsoever about the location of Brown.
In fact, Jones does not own a Ford, but by sheer coincidence, Brown really is in Barcelona. Again, Smith had a belief that was true and justified, but not knowledge.
In both of Gettier's actual examples (see also counterfactual
conditional), the justified true belief came about, if Smith's
purported claims are disputable, as the result of entailment (but see
also material conditional) from justified false beliefs that "Jones
will get the job" (in case I), and that "Jones owns a Ford" (in case
II). This led some early responses to Gettier to conclude that the
definition of knowledge could be easily adjusted, so that knowledge
was justified true belief that does not depend on false premises.
More general Gettier-style problems
In a 1966 scenario known as "The sheep in the field", Roderick
Chisholm asks us to imagine that someone is standing outside a field
looking at something that looks like a sheep (although in fact, it is
a dog disguised as a sheep). They believe there is a sheep in the
field, and in fact, they are right because there is a sheep behind the
hill in the middle of the field. Hence, they have a justified true
belief that there is a sheep in the field. But is that belief
knowledge? A similar problem which seeks to be more plausible called
the "Cow in the Field" appears in Martin Cohen's book 101 Philosophy
Problems, where it is supposed that a farmer checking up on his
favourite cow confuses a piece of black and white paper caught up in a
distant bush for his cow. However, since the animal actually is in the
field, but hidden in a hollow, again, the farmer has a justified, true
belief which seems nonetheless not to qualify as "knowledge".
Another scenario by
After arranging to meet with Mark for help with homework, Luke arrives at the appointed time and place. Walking into Mark's office Luke clearly sees Mark at his desk; Luke immediately forms the belief "Mark is in the room. He can help me with my logic homework". Luke is justified in his belief; he clearly sees Mark at his desk. In fact, it's not Mark that Luke saw; it was a marvelous hologram, perfect in every respect, giving the appearance of Mark diligently grading papers at his desk. Nevertheless, Mark is in the room; he is crouched under his desk reading Frege. Luke's belief that Mark is in the room is true (he is in the room, under his desk) and justified (Mark's hologram is giving the appearance of Mark hard at work).
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 is 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 did not 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:
That looks to me like Mark in the room. No factor, right now, could deceive me on this point. Therefore, I can safely ignore that possibility. "Mark is in the room" (or, "I can safely treat that as Mark").
The second line counts as a false premise. However, by the previous argument, this suggests we have fewer justified beliefs than we think we do. Constructing arbitrary Gettier problems The main idea behind Gettier's examples is that the justification for the belief is flawed or incorrect, but the belief turns out to be true by sheer luck. Thus, a general scenario can be constructed as such: Bob believes A is true because of B. Argument B is flawed, but A turns out to be true by a different argument C. Since A is true, Bob believes A is true, and Bob has justification B, all of the conditions (JTB) are satisfied. However, Bob had no knowledge of A. Responses to Gettier The Gettier problem is formally a problem in first-order logic, but the introduction by Gettier of terms such as believes and knows moves the discussion into the field of epistemology. Here, the sound (true) arguments ascribed to Smith then need also to be valid (believed) and convincing (justified) if they are to issue in the real-world discussion about justified true belief.  Responses to Gettier problems have fallen into one of three categories:
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.
One response, therefore, is that in none of the above cases was the
belief justified because it is impossible to justify anything that is
not true. Conversely, the fact that a proposition turns out to be
untrue is proof that it was not sufficiently justified in the first
place. Under this interpretation, the JTB definition of knowledge
survives. This shifts the problem to a definition of justification,
rather than knowledge. Another view is that justification and
non-justification are not in binary opposition. Instead, justification
is a matter of degree, with an idea being more or less justified. This
account of justification is supported by mainstream philosophers such
as Paul Boghossian   and Stephen Hicks. In common sense
usage, an idea can not only be more justified or less justified, but
it can also partially justified (Smith's boss told him X) and
partially unjustified (Smith's boss is a liar). Gettier's cases
involve propositions that were true, believed, but which had weak
justification. In case 1, the premise that the testimony of Smith's
boss is "strong evidence" is rejected. The case itself depends on the
boss being either wrong or deceitful (Jones did not get the job) and
therefore unreliable. In case 2, Smith again has accepted a
questionable idea (Jones owns a Ford) with unspecified justification.
Without justification, both cases do not undermine the JTB account of
Other epistemologists accept Gettier's conclusion. Their responses to
the Gettier problem, therefore, consist of trying to find alternative
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 not yet been satisfactorily defined, so that JTB
(justified true belief) may be defined satisfactorily is still
problematical, on account or otherwise of Gettier's examples. 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
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 of the kind often ascribed to James,
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. Peirce emphasized
fallibilism, considered the assertion of absolute certainty a barrier
to inquiry, and in 1901 defined truth as follows: "
p is true S believes that p if p were true, S would believe that p if p weren't true, S wouldn't believe that p
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):
p is true S believes that p if p were true, S (using M) would believe that p if p weren't true, S (using method M) wouldn't believe that p
I see a barn
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
I see a red barn.
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. Richard Kirkham's skepticism Richard Kirkham has proposed that it is best to start with a definition of knowledge so strong that giving a counterexample to it is logically impossible. Whether it can be weakened without becoming subject to a counterexample should then be checked. He concludes that there will always be a counterexample to any definition of knowledge in which the believer's evidence does not logically necessitate the belief. Since in most cases the believer's evidence does not necessitate a belief, Kirkham embraces skepticism about knowledge. He notes that a belief can still be rational even if it is not an item of knowledge. (see also: fallibilism) Attempts to dissolve the problem 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
Gettier's cases are not really cases of justified true belief, or Gettier's cases really are cases of knowledge after all,
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 that 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 analytic 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. Experimental research Some early work in the field of experimental philosophy suggested that traditional intuitions about Gettier cases might vary cross-culturally. However, subsequent studies have consistently failed to replicate these results, finding instead of that participants from different cultures do share the traditional intuition. Indeed, more recent studies have actually been providing evidence for the opposite hypothesis, that people from a variety of different cultures have surprisingly similar intuitions in these cases. Notes
^ 'Conditions of Knowledge' (1965). Chicago: Scott, Foresman
^ Timothy McGrew (2007), Internalism and Externalism, Abingdon, Oxon:
Routledge , chapter 1
^ John L. Pollock; Joseph Cruz (1999), Contemporary theories of
knowledge, Lanham, Md: Rowman & Littlefield Publishers,
pp. 13–14, ISBN 0-8476-8936-0, 0847689360
^ a b
Mario Alai: "Subjective and Objective Justification in the Solution of
Gettier’s Problem", in Selected Proceedings of the SILFS 2010
International Congress, edited by S. R. Arpaia, L&PS - Logic and
Text of the article
Gettier problem at PhilPapers
Zalta, Edward N. (ed.). "The Analysis of Knowledge". Stanford
Encyclopedia of Philosophy.
Gettier problem at the Indiana
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