This section of the text Pojman has edited is Chapter 19 of Book 4 of John Locke's masterpiece, An Essay Concerning Human Understanding. It may strike you oddly, but the essay is around 700 pages in total length. (Try writing that in a Blue Book!) Needless to say, we will be taking only a very brief look at what Locke has to say. (We will return to the Essay in Unit 3 which deals specifically with Epistemology.) But this particular chapter is important because in it Locke argues that the philosophical quest entails a respect, even love, of the truth. That is, Philosophy is NOT just whatever you want it to be; it is NOT just a matter of one's own opinion.
In Socrates we saw a similar reverence for the truth. He spent his entire life looking for it, and was even willing to give up his life rather than give up his search for the truth. And, even though he claimed not to have reached the goal himself, nor had anyone else he met, he still believed that we must strive after the truth.
But what is truth? Isn't the truth relative to each individual (this is a position called "epistemic relativism" which we will deal with in more detail later)? Don't I have my own truth which might be different from yours?
The short answer to the last two questions is, NO. Most people who propose Relativism of this type are simply confused about what the word 'truth' means. So, let's set the record straight right now!
Definition: 'Truth' means, however the universe actually is (as opposed to how we believe it is).
When philosophers like Locke, and Socrates, and Plato, and Russell, use the word 'true' they simply mean that some particular assertion accurately expresses the way things are. "But wait," you might say, "we can't know how the universe really is in-itself, so how can we know what propositions are true?" If one is a skeptic (i.e., believes we cannot have knowledge) then it would make sense to say that we cannot know the truth. But even if the skeptic is right and we cannot know how the universe is, that does not change the fact that the universe is one way or another. So, just because we may be limited in our epistemic abilities, does not entail that there is no truth. It is a mistake to confuse Skepticism (the view that we cannot know the truth) with Relativism (the view that there is no truth to be known).
But John Locke is neither a skeptic nor a relativist; he believes that there are certain facts about the world, and that we can know many of them. This assumption makes it essential that we know the difference between believing and knowing, and that we be capable of distinguishing the two. This is, in large part, what Locke is attempting to do in his Essay. In the attempt to articulate the distinction between knowledge and opinion, we are led to a discussion of the rules of believing and knowing, and more importantly for us, the necessity of evidence for formulating and maintaining beliefs and knowledge. It is not enough to simply WANT something to be true, we must have REASONS for our beliefs. This is the subject of Chapter 19 of Book Four, which Pojman has entitled, "Philosophy as the Love of Truth versus Enthusiasm," but which Locke simply calls, "Of Enthusiasm."
The sign of the philosopher is loving knowledge for the sake of the truth itself, not for the sake of what we can do with it, or what it can do for us.
Locke's notion of revelation differs substantially from the more common conception that revelation is either ir-rational, or supra-rational. Locke finds it not only odd, but impious to suggest that God could violate his own laws (the laws of reason). Any such violation would suggest either an inappropriate capriciousness, a lack of knowledge, and/or a limitation of God's power. But by definition each of these are impossible as God is an omnipotent, omniscient, and omnibenevolent being.
Neither will it do to claim that we simply don't comprehend God's abilities for we are created by God to understand the mind of God ("Let us make humans in our image..."). That is, God has given us the faculty of reason that we may understand the universe of which we are a part. Thus, if someone claims to accept a belief on the basis of revelation (i.e., they "believe it on faith") which is a violation of reason, they are acting both irrationally and irreverently.
Unfortunately, all too often what passes for divine revelation is really nothing more than "enthusiasm." That fact that I am strongly convinced of a proposition is insufficient for me to accept it, as is the fact that it comes with a kind of "internal light." The truth will always be accompanied by abundant evidence. Our job, the job of doing Philosophy, is to uncover that evidence. And if that evidence is not forthcoming, we ought to withhold our assent, even if it's a proposition we desperately want to be true.