The ability to recognize knowledge and the ability to acquire knowledge can be seen as the foundation of all our beliefs about the external world. Typically knowledge is defined as justified, true, belief. It has been argued that this definition is imperfect before; here I will give further reasons to believe that we need a new definition of knowledge, as well as propose such a possible replacement.
Let’s start with the requirement that knowledge be true. This seems reasonable at first, but, considering what we actually demand of the statements that we call knowledge, it defeats the point of labeling a thought knowledge. This is because knowledge is supposed to be how we discover truths about the world. However if part of knowledge is a requirement that it be true we could never be sure if a statement was knowledge, because to know that it is true me must have knowledge about it, but to have knowledge about it we must know that it is true, … ect. For example consider two scientists examining a ball in a box. One scientist takes the ball out of the box, observes its color and then places it back, and the other scientist does the same. Now suppose those scientists disagree about the color. It is true that given our third party knowledge of the situation we are able to say which scientist has knowledge and which doesn’t (given that it is our thought experiment and we really know the color of the ball). This doesn’t help the scientists themselves however. Their beliefs about the color of the ball are equally justified. They could perform experiments that justify one color belief more than the other, but there is nothing they can do to guarantee that it is the truth, and thus they can never be sure that they have knowledge about the color of the ball. This seems to defeat the point of having knowledge, because having knowledge is something that is supposed to help us get at truths in the external world, but it seems like we can never be sure that we have knowledge, and hence must forever be doubtful of the external world.
Likewise the requirement that knowledge be truth would lead us to conclude that most scientific theories weren’t knowledge. Certainly past theories weren’t knowledge, since modern scientists have shown them to be false. However given this track record of improving theories it is likely that the current theories will be discarded as well, and hence aren’t the truth (although they may be good approximations). If we accept the standard definitions of knowledge it seems like we should conclude that scientists never have knowledge about the things they study, and since this is the exact opposite of what we should conclude it is another good reason to discard the standard definition of knowledge.
Another aspect of the standard definition of knowledge that we might find fault with is the requirement that it be a belief. This is perhaps due to the shifting nature of what exactly we consider a belief, but let us go with the following definition: a belief is a disposition to act in a certain way. For example if you believe that the moon is made of cheese you will tell other people that the moon is made of cheese, and you won’t hesitate to take a bite of it given the chance. Reflection upon the nature of belief has led many people to think that beliefs are best demonstrated though the choices a person makes, and not what they say. For example if you claim that you aren’t scared of mice (thus telling us that you believe mice aren’t scary), but then scream and run away when you see one we are justified in thinking that you really do believe mice to be scary. Consider then the following situation: an engineer has designed a new safety device for a machine, and he or she has proved without a doubt, from well tested principles, that it is impossible for it to cause an injury. We then ask the engineer to test that safety device, say by sticking their hand into the machine. I think it is quite reasonable for engineer to refuse. This however demonstrates that he or she doesn’t believe that the safety of the device is absolutely certain. However the principles that its functioning is based on are so well proven that we conclude that they do have the knowledge that it will work, simply not the belief that it will. Because of situations like this I think the requirement that knowledge must be a belief should be dropped as well.
What does that leave us with? Well, from the above criticisms I think we should conclude that knowledge is simply a justified statement, and even though we have done away with two thirds of the standard definition it is still reasonable to consider knowledge as leading us to the truth about the external world. First though it is important to clear up exactly what we mean by justified. There are three basic ways a statement can be justified. One is that it can be shown to be a tautology, and although this is the most important case for mathematical knowledge I will ignore it for the remainder of this post, since tautologies tell us nothing new about the external world. Another possibility is that the statement can be supported by evidence, in a Bayesian fashion. I call this possibility original justification, and a statement that is supported by original justification strong-knowledge. Finally, a statement may be justified by showing that it is a consequence of other statements that are considered to be knowledge. I call this possibility dependant justification, and statements that are supported in this way weak-knowledge.
As the above categories show it is hard to define knowledge as being something that we either have or don’t have. Instead we become more or less certain of a statement by making observations (by having stronger or weaker justification), but we can never be completely sure that it is true or false. This means that we can never completely remove the possibility of error, but, as the example given above with the scientists attempting to determine the color of a ball showed, we shouldn’t expect that absolutely certain knowledge is possible anyways. The possibility of error does not reduce the usefulness of knowledge, or its validity as a reason for action, nor should it give us reason to doubt the possibility of knowledge or the existence of an objective world.
Secondly the strong-knowledge / weak-knowledge distinction is important when considering to what extend we should rely on a statement, and how we should talk about knowledge in general. Sometimes when people refer to knowledge they really mean strong-knowledge (for example when we say things such as: “you can’t have knowledge about the future”). Strong-knowledge, in general, is more useful, and more reliable than weak-knowledge. For example you may think that a specific weak-knowledge claim is highly probable because the strong-knowledge claims that it is based on are confirmed to a high degree. What this doesn’t take into account though is that there may be other factors at work that make your claim false. For example we can have strong-knowledge regarding the claim: “only men have beards” however we can’t deduce the claim “women can’t have beards” with the same degree of certainty because we have omitted another factor, namely that women who have beards remove them due to social pressures. This also explains why the engineer mentioned above may have been justifiably hesitant to try their proven safety measure; they had only weak-knowledge concerning it, not strong knowledge. It is too easy to make mistakes when deducing weak-knowledge from strong-knowledge, which is why I suggest that when we think about investigations into the truth we concern ourselves primarily with strong-knowledge (even though we use weak-knowledge on a daily basis to get by practically in the world).
You may be inclined to point out now that many strong-knowledge beliefs rely on other strong-knowledge beliefs in order to connect their evidence to their theory. For example if you measure the light from the sun in order to collect evidence for a hypothesis about its temperature you conclusions depend on strong-knowledge about the connection between radiated energy and temperature. I would say that this does indeed make the boundary between strong and weak knowledge a bit gray, as it should be. Generally we create standards of certainty (very high standards) which if a statement makes can be used as part of the procedure by which we determine if evidence confirms or denies a statement. However no matter how weak you make these standards there are some statements that can never be moved from the domain of weak-knowledge to that of strong-knowledge, for example claims about a future event, since one can only collect evidence after the event has already happened.
Am I absolutely sure that this definition of knowledge is satisfactory for all cases? No, but I have confirmed it to a sufficient degree to consider it knowledge, until something superior is proposed.