If one subject, more than any other, has come to dominate philosophical inquiry it is epistemology. Epistemology deals with questions concerning the nature of knowledge, what we can know, and how we come to know it. Modern philosophy’s focus on epistemology might be considered the legacy of René Descartes; however, as we have already seen, epistemological concerns were being addressed as early as Plato.
As we know, one of the concerns of philosophy involves coming up with definitions. These, more often than not, are provided in terms of necessary and sufficient conditions. For example, a necessary condition for being a sister is that you are female. However, this alone is not sufficient for sisterhood; it is also necessary that you be a sibling. As such there are two necessary conditions for being a sister and these are jointly sufficient. Therefore, we can define a sister as a female sibling.
There are generally thought to be three individually necessary and jointly sufficient conditions for knowledge. Firstly, in order to know something you must believe it (ignore the fact that sometimes people will say such things as ‘I know Boris Johnson is the Mayor of London but I don’t believe it!’); this is known as the belief condition. Obviously, it’s not sufficient for having knowledge that one has a belief. I, for example, may believe that as you read this you are slowly transforming into a giant beetle. But, could I be said to know this? If not, why not?
Of course, I don’t know that you currently undergoing metamorphosis. Why not? Well, simply because it’s not true (I hope). The second condition, then, for a particular claim to be known is that it be true; the truth condition. Having knowledge, then, involves having some sort of true belief, but is this enough? Consider the following claim: ‘I know that you are a Capricorn’. Now, roughly 8.33% of you will be Capricorns, and let’s suppose that you’re one of them (even if you aren’t). In that case I have a belief that you’re a Capricorn and my belief is true. But do I know that you are a Capricorn?
Most people would, I believe, say not. Why not? Well, perhaps the reason that my true belief would not count as knowledge has something to do with the fact that this claim is only accidentally true, if it is true at all. That is to say, if my belief is true, it is due merely to the fact that you happen to be one of the 8.33% of people who are Capricorn and not due to my having any particular reason or justification for holding this belief. If, however, my true belief that you are a Capricorn was justified in some way (for example, by my knowing that you were born on December 25th) then most people, I think, would agree that I know you are a Capricorn. This final necessary condition is known as the justification condition.
As such, we may define knowledge as justified true belief; these three conditions being individually necessary and jointly sufficient for knowledge. That is to say, if you have knowledge you must have a justified true belief and if you have a justified true belief then you have knowledge. Or not!
In 1963 Edmund Gettier published a very short paper entitled ‘Is Justified True Belief Knowledge?’ in which he presented counterexamples to the tripartite definition of knowledge. Gettier’s paper had a huge impact on philosophy and a number of Gettier-like counterexamples have been constructed to show that a justified true belief is not always sufficient for knowledge. Gettier’s own examples are as follows:
Case 1: Smith and Jones both apply for a job. Smith has a justified belief that ‘Jones will get the job’, and further that ‘Jones has 10 coins in his pocket’. This entails Smith’s belief that ‘the man who will get the job has 10 coins in his pocket’. Now, in fact, Jones will not get the job, Smith will (although he doesn’t know it yet). Furthermore, Smith happens to have 10 coins in his pocket (also unbeknownst to him). Does Smith know that ‘the man who will get the job has 10 coins in his pocket’?
Case 2: Smith has a justified belief that ‘Jones own a Ford’. This entails Smith’s belief that ‘Either Jones owns a Ford or Brown is in Barcelona’, even though he doesn’t actually know where Brown is. However, unbeknownst to Smith, Jones does not own a Ford, yet coincidently Brown happens to be on holiday in Barcelona. Does Smith know that ‘Either Jones owns a Ford or Brown is in Barcelona’?
Most people here are inclined to respond ‘no’ in these cases; as such, it might be supposed that justified true belief is not sufficient for knowledge after all. There are a couple of ways in which we can avoid the problem. Firstly, we might say that (despite what many are inclined to believe) Smith does in fact know the the man who gets the job has ten coins in his pocket, etc. Secondly – and this is the more likely option – we might say that these examples are not counter-examples at all as Smith’s beliefs aren’t really justified – or at least they are not justified in the right kind of way (perhaps because they depend on false beliefs that Smith holds).
As such, what these examples highlight is the major difficulty with justifying one’s beliefs; what, if anything, counts as an adequate justification? When can we be said to know something – for certain? There are two main schools of thought here – Rationalism and Empiricism. Rationalists, such as Descartes, believe that certain knowledge can be gained via the use of reason alone. This form of knowledge is known as a priori knowledge. In opposition to this, Empiricists believe that knowledge must come via experience derived from the senses: a posteriori knowledge. This division between Rationalism and Empiricism can be traced back to Plato and Aristotle.
One of the major benefits of a priori knowledge is that it delivers certainty; it is indubitable. For example, the proposition that ‘2+2=4’ or that ‘either Jim is in Edinburgh or he’s not’ just have to be true (they are necessarily true) and this is established without recourse to the senses. Some a priori claims, such as the aforementioned ‘All sisters are female siblings’, are also called analytic. This is due to the fact that they contain no more information than is already contained in the meaning of the terms (‘sister’ just means ‘female sibling’ so the claim is really ‘all female siblings are female siblings’). In establishing the truth of all of these propositions there is no need to appeal to the senses; the truth of these claims is not established by your counting your fingers (hopefully), going to check whether I’m here or not, or interrogating sisters.
The problem, an empiricist might claim, is that while such a priori/ analytic propositions may be necessarily true, they are actually rather trivial and worthless. What we really want to know, they argue, is whether ‘Jim is in Edinburgh’ or if ‘Lucy is a sister’, and the only way we can establish the truth (or falsity) of such a posteriori claims is by looking for Jim or asking Lucy. If such propositions are true, they are only contingently true; that is, they happen to be true but could have been false (Jim need not be in Edinburgh and Lucy could have been an only child). Note also, that these propositions are not analytic but rather synthetic; they bring together different concepts and, as such, offer meaningful information. The problem, of course, is that, as Gettier discovered, they are far from certain. For example, it may be that it was Jim’s identical twin brother you saw in Edinburgh while Jim is in fact sunning himself on a beach somewhere, and Lucy may be a compulsive liar.
So, there we have it. In simple terms, knowledge can be defined as justified true belief, however, it is difficult to establish what exactly counts as an adequate form of justification. Rationalists maintain that useful knowledge can be gained through the use of reason alone. Such a priori/ analytic claims are self justifying and, therefore, necessarily true. Empiricists, however, claim that the price of this certainty is triviality and that the only route to useful ‘knowledge’ about the world is experience
