Historically, since Plato, the most frequent definition of knowledge has been Justified True Belief (JTB). Until recently (the 20th century), philosophers believed in a foundation for JTB. The Cartesian Rationalists believed that some beliefs were certain because they were self-evident truths that survived Descartes method of doubt. The empiricists believed that some beliefs were self-evident truths because they were in agreement with observational experience. The Kantian Idealists believed that some beliefs were synthetic a prioris and as such were also certain.
For these three philosophical traditions, Justification in JTB meant simply showing that a belief could be deduced from a foundational belief using the rules of logic. In the 20th century the following happened. The Pragmatism of Peirce, James, Dewey, and their successors, and the Critical Rationalism of Karl Popper argued that there were no certain foundational beliefs, and that neither Rationalism, nor Empiricism, nor Idealism nor any other philosophical school could supply such foundations. Thus, fallibilism, the view that no beliefs about the world are or can be certain, became accepted as the dominant position in academic philosophy. Because of this, the notion that knowledge was JTB had to undergo change. Some philosophers have tried to keep the notion of JTB by arguing that our ideas about “Justification” had to change. “Justification” could no longer mean deduction from certain foundations, but had to mean something else. In turn, the group that wanted to change the meaning of Justification split into a number of schools. The two main ones are what I would call the Wittgensteinian approach, and the “good reasons” approach.
The Wittgensteinian approach basically says that any theoretical system has to have “hinges” or basic premises about how to use language, ontological assumptions and epistemological assumptions. People who don’t accept these premises are just refusing to play the language game within whose context a theory is presented. Knowledge is relative to the language game and its basic premises. It is constituted of these premises and all the conclusions that can be deduced from them. Knowledge is as before. It is still JTB, but we no longer justify it in terms of certain premises, but only in terms of the premises of the language game. Obviously, while this position is consistent it also presents a view of JTB and knowledge that is profoundly relativistic in character, and it also begs the question of justification by insisting that the basic premises of the language game don’t need justification. But this is after all, an empirical question. If one is willing to play the language game, then no justification is needed. But if one is deciding whether to play it or not then the absence of Justification means that the knowledge produced by such systems is not Justified True Belief at all, but rather belief that may not be true, and that is not justified until one decides that the foundational beliefs in such a system don’t need to be justified.
The other main approach retaining “justification” is the good reasons approach. Its basic tenet is that justification should no longer be viewed as deduction from certain foundations, but rather as supplying “good reasons” for accepting the foundations of any theoretical system. While this move may seem quite reasonable, we can’t overlook the fact that “good reasons” don’t provide any logical warrant for accepting the foundations of theoretical system and also we can’t overlook the fact, that no proponent of the “good reasons” approach has yet been able to develop a coherent way of distinguishing good reasons from bad ones. Finally, however, having a good reason to believe a foundational belief, cannot guarantee the certain truth of that belief. So again we are left with a situation where the belief in question may not be true, and also is not “justified” in the sense that the justification provided can guarantee the truth of the belief. Thus if we insist on the JTB notion, the consequence is that “knowledge” is either relative, or that no knowledge exists. In terms of set theory, such a definition either gives us relativism or it gives us knowledge as the empty set, an unacceptable consequence if we think that we do have some knowledge.
Moving away from “justificationist” responses to the JTB crisis, Critical Rationalism and Evolutionary Epistemology contend that since justifications for beliefs or knowledge claims that make them certain can’t be provided, the best move is to change the definition of knowledge by getting rid of justification. This leaves true belief. However, because of fallibilism, we can never know for certain if a belief of ours is true. So if we say that knowledge is True Belief, we are left with the problem that something that we think is knowledge, may prove false and therefore is not knowledge at all. If this happens, we can say that the belief never was knowledge in the first place, a counter-intuitive result considering that we’ve had theories like Newton’s which we’ve thought of as knowledge for hundreds of years.
Well, Critical Rationalism (CR) and Evolutionary Epistemology (EE) ask, what if we go the whole way and say that knowledge needs neither to be justified nor to be true, but only needs to survive our best efforts at criticism, testing, and evaluation. If we make this move then we are led to the position that (1) knowledge exists at any point in time, and also that (2) some of that knowledge may prove false tomorrow, and (3) much more of it may, unbeknownst to us, be false today. So the CR/EE position is that knowledge is not justified, and it is not necessarily true, but it is what has survived our critical experience, viewed very broadly.
At this point you may ask, well if knowledge can’t be justified then how do we establish it? And the answer to this question is, that we do not “establish” or “prove” it. What we do is to test competing knowledge claims by criticizing, testing and evaluating all reasonably coherent competitors, and then by evaluating which of these stands up best to our criticism. It is the knowledge claims that survive along with the meta-claims comprising the track record of our attempts to overturn them and their competitors that comprise our knowledge.
The foregoing view is my interpretation of past trends. Since most philosophers are unreconstructedly “justificationist,” most of them would probably ignore the CR/EE theme as a sideline, and emphasize variations on the good reasons approach more heavily. However, after almost 50 years of good reasons efforts to find coherent justifications for knowledge claims, I think that this sort of tilting at windmills may have run its course, and perhaps more people may be ready for the anti-justificationist, criticalist approach offered by CR. If, of course, they don’t succumb to constructivist relativism first.
However, in recent years, post-modernism seems also to be weakening, so perhaps the constructivist wave is beginning to break on the shoals of reality, and that we are not far from a resurgence of realism and a critical approach to evaluation. I hope so, and I am doing all I can to see to it that such an approach is a respectable one in the field of Knowledge Management.