Philosophers (at least in the western tradition) have struggled with the connection between knowledge and certainty since they started to think about that matter. Socrates famous saying: ‘The only thing that I know, is that I know nothing’ makes this very clear. To understand better, why Socrates believed, that he only knows one thing, we should look at the definition of the notion ‘knowledge’. The classical definition has it, that in order to know a certain claim three conditions must be met. Consider the proposition (p) that Socrates was a philosopher. One knows that p (Socrates was a philosopher), if
- p is true;
- one believes that p;
- one is justified in believing that p.
For our examples, this means that we only know that Socrates was a philosopher, if Socrates actually was a philosopher (truth condition), if we really think that he was a philosopher (belief condition) and if we are justified in believing so (justification condition). It is easy to see, why the truth condition must be satisfied. You can’t know something false; if it is false, then you don’t know it. If it turned out, that Socrates was in fact a merchant, who never had one single philosophical thought, proposition p would be false. In that case, you wouldn’t know that Socrates was a philosopher, because he wasn’t. The second condition seems to be trivial; but it actually isn’t. For most philosophers ‘believing p’ describes a certain mental state, that is defined by a its content namely p. More over, if you believe that Socrates was a philosopher, you think that this is true. As philosophers have put it: ‘Belief aims at truth’. In our everyday language we sometimes use ‘believing’ as an opposite for ‘knowing’. It is important to see that here the philosophical language for the sake of clarity is narrower than our everyday language. This leads us directly to the third condition for knowledge - justification. It is not enough for knowledge that the belief, that p, is true, it must also be true for the right reason. There are many good reasons for knowing that Socrates was a philosopher. You could have learned about it at the university, where experts of ancient philosophy have taught you that. Or, you could have seen a statue of an ancient philosopher at a museum that had the name Socrates engraved on it. But, if you just had guessed that Socrates was a philosopher, you wouldn’t know it. For, if a belief is accidentally true, then it is not knowledge.
The claim that knowledge can be defined as justified true belief matches many of our intuitions about it. There is prima facie no need for something like certainty. However, it has been René Descartes (1596–1650), who has awakened the philosophers from a slumber. By presenting a sceptical scenario about a deceiving evil daemon he had asked, why we are so sure that we know anything. Couldn’t it be that because we are deceived by this evil daemon all our beliefs about the world are false? Couldn’t it be that we all are living in a matrix? Faced with scenarios like these, how can we know that our beliefs about the world are actual, true beliefs about the world? If this possibility exists, how then do we know anything at all? It is at this point, where the notion of certainty made its first appearance in epistemology. For Descartes solution to this issue was to identify at least one claim that we know with certainty, which means that it cannot be doubted. According to Descartes, the only proposition that we can know with certainty is ‘I think, therefore I am’ (‘cogito, ergo sum’). Descartes reasoned that it is impossible to doubt that you are thinking; for even if you’re in error or being deceived or doubting, you are nevertheless thinking; and if you are thinking, you exist.
Descartes conclusion has been challenged in several ways. First, as psychology and cognitive science tell us, human beings aren’t the perfect homo philosophicus. We often judge on an uncertain basis using particular heuristics. And yet, using heuristics very often leads to knowledge. Second, as philosophical reasoning has shown the condition of certainty is much too strong for something to count as an instance of knowledge.
Hence, although philosophers have wrested with the idea that certainty is a condition for knowledge, they have finally abandoned it in favour of other notion, such as safety, that fit much better our understanding of knowledge.
Let me end this entry with a poem by the German illustrator and poet Wilhelm
Sokrates, der alte Greis,
Socrates, the aged and wise,
(translated by G. Papadopoulos)