Knowledge is usually defined as Justified True Belief (JTB).
In our article on revelational epistemology, we actually defined it as such:
A truth claim is a proposition or statement that a particular person or belief system holds to be true. A truth claim is not necessarily the truth.
A truth claim is a statement about reality. Truth claims can therefore not exist independent of a mind. All truth is also truth claims. All truth claims are not necessarily correct/valid. Therefore, truth cannot exist independently of a mind -- as truth is correctly interpreted reality.
A truth claim is therefore only true when it corresponds to reality. The truth is, therefore, a truth claim that corresponds to reality.
Reality is the sum or aggregate of all that is real or existent, as opposed to that which is merely imaginary. Therefore reality can exist independent of a (human) mind to interpret it (not independent of God’s mind - more later). An interpretation of reality (or truth claim) that corresponds to the objective reality would be the truth.
Therefore, an interpretation of reality is a truth claim. The truth, is a truth claim that corresponds to reality.
Knowledge is justified, true belief, or a truth claim that is actually the truth -- an interpretation of reality that corresponds to the objective reality.
Therefore, true and justified knowledge is an interpretation of reality (truth claim) that corresponds to reality.
Now a classic attack against the traditional formulation of knowledge as JTB are Gettier's
One of Gettier's Counter Examples goes like this:
Smith and Jones have applied for a particular job. 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 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’s suppose, says Gettier, that Smith sees the entailment from [d] to [e], and accepts [e] on the grounds of, for which he has strong evidence. In this case, Smith is clearly justified in believing that [e] is true.
But then we’re to imagine that he, Smith, and not Jones, gets the job. And, unbeknownst to Smith, he himself has ten coins in his pocket. Proposition [e] is then true, although the proposition from which he inferred it, [d], is false.
In other words, [e] is true, Smith believes [e], and Smith is justified in believing [e]. But, says Gettier, we don’t want to say that Smith knows that [e] is true, because [e] is true in virtue of the number of coins in his pocket, which Smith has no idea of! Smith got lucky. If he hadn’t had ten coins in his pocket, the proposition wouldn’t have been true at all. (Notice that no sceptical problem is being raised, since everything we have said, however, is compatible with the idea that if Jones had got the job, we would have granted Smith that he knew Jones would get the job).
Supposedly he was justified in expecting Jones to get it and was right in the person getting it having 10 coins.
Therefore, the objection goes, you can fit all the requirements of JTB and still not really have knowledge. Let's analyse the example and see whether this in in fact the case:
In the following - J: Justified, B: Belief, T: True.
Proposition of Jones getting the job:
J: Jones will get the job and Jones has 10 coins and company president said so.
B: Smith believes the man who has 10 coins will get it.
T: Jones got the job. (WE KNOW THAT THIS IS NOT TRUE)
So, we know that Smith did not actually fulfil the relevant set of JTB to qualify as knowledge that Jones will get the job, since "actual" T was not relevant to J or B. In other words the justification is relevant to Jones, but not to Smith since "actual' T is that Smith got the job
Smith getting the job:
J: Smith had no Justification that he would get the job
B: Smith believes that the man with 10 coins will get it.. (But this is a derived proposition from Smith believing that Jones has 10 coins... and ultimately it was an erroneous understanding that Smith had of this proposition because it was always necessarily tied to Jones having 10 coins)
T: Smith got the job.
From this breakdown it is easier to see that there was never actually a case in which Smith actually had a relevant set of JTB (he simply had no idea that he himself would get the job).
Gettier does not actually break down the example like this, and so, I can see why people can be subtly drawn into the idea that Smith had fulfilled JTB but didn't actually have knowledge.
NOTE - Most of the preceding was drawn from the Reformed Presup Apologetics Group on Facebook