John Locke

John Locke on the Role of Truth in Philosophy


The Complete Text of Locke's "An Essay on Human Understanding"

In 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. 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.) This chapter is important because in it Locke argues that the philosophical quest entails a respect, even love of, the truth. Philosophy is NOT whatever you want it to be; it is NOT just a matter of opinion.

But what is the 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 be clear about what the word means:

Definition: 'Truth' means, however the universe actually is.

When philosophers like Locke, and Socrates, and Plato, and Russell, use the word 'true' they simply mean that some particular assertion, proposition, belief, etc., accurately reflects 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 knowledge 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).

John Locke is neither a skeptic nor a relativist; he believes that there are facts about the world, and we can know many of them. This assumption makes it essential that we know the difference between believing and knowing. This is what Locke is attempting to do in his Essay. Articulating the distinction between knowledge and opinion, we are led to a discussion of the rules of believing and knowing, and more importantly, 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."

  1. What is The Value of Truth (i.e., knowledge)?

    1. Instrumental Value - Good for the sake of something else (e.g., what we can do with it)

    2. Intrinsic Value - Good for its own sake

    NOTE: The sign of the genuine philosopher is loving truth for its own sake, not for the sake of what we can do with it, or what it can do for us.

  2. What Counts as Evidence for Belief Justification? (four possible grounds of assent)

    1. Reason - "Nature’s Revelation"

      1. Self-evident beliefs (i.e., tautologies and definitional truths)

      2. That which can be deductively demonstrated (i.e., the rules of logic and mathematics)

      3. That which can be inductively inferred (i.e., all empirical knowledge)

    2. Divine (special) Revelation - "discoveries communicated by God immediately"


      NOTE: To understand Locke's position it is essential to understand that revelation is an "enlargement" of rational knowledge, but it can never be contrary to reason. Divine revelation cannot contradict reason, because God is a rational being. In fact, God is the rational being. What we call reason just is a reflection of how God thinks. Thus, it cannot be revealed that 2 + 2 = 5, or that squares have three sides, or anything which is a contradiction of the principles of reason. Another way of saying this is, God cannot contradict himself. So, one way we test a revelation to see if it is genuine is by comparing it to what we know through reason. A revelation must be consistent with reason.

      The second test for a legitimate revelation is whether the belief is something we could come to know on our own. Since God has equipped us with natural abilities (senses and the faculty of reason), he expects us to use those tools to investigate the world. When God gives us a revelation, it must be a truth that transcends our ordinary capacities of knowledge. If someone claims as revelation something that is within our ordinary powers, we know it is not genuine.

      Thus, genuine revelation must not contradict reason, while it exceeds our ordinary abilities of knowing. But given that we are rational by nature (i.e., made in God’s image) we will be dubious of any belief that is not sufficiently supported by evidence. Knowing this, God, when he gives us a revelation, always provides objective evidence that the revelation is genuine. That evidence is what people commonly call a miracle: an observable event which transcends our ordinary capacity for understanding without violating the rules of reason.


    3. Authority - believing what someone says simply because THEY are the one who said it

    4. Enthusiasm - believing what we want to believe, when there is no other evidence other than our desire to believe it

Of the four possible types of evidence for a belief, only two —reason and revelation—are reliable. For Locke, the truth will always be accompanied by sufficient 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.


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