Chapter 5. What Can We Know?

Chapter 5

What Can We Know?

Copyright by Paul Herrick. For class use only. Not for distribution. This chapter: 16 pages of reading.

To abandon facts is to abandon freedom. If nothing is true, then no one can criticize power, because there is no basis upon which to do so. If nothing is true, then all is spectacle.

— Timothy Snyder, On Tyranny: Twenty Lessons from the Twentieth Century.[endnoteRef:1] [1: Timothy Snyder, On Tyranny: Twenty Lessons from the Twentieth Century (New York: Tim Duggan Books; 1st ed. (February 28, 2017). I was drawn to this passage by the professor Tom Taylor, Seattle University, during a history conference at the University of Washington in August 2017. ]

1. Relativism, Skepticism, and the Birth of Epistemology

Many people today claim that there is no such thing as objective truth. Truth, they confidently say, is relative to each person. By this they mean two things: First, each person has a unique perspective. Second, each person’s perspective is equally valid because there is no objective basis for saying that one person’s belief is true and another’s is false. Thus, if you believe something is true, that makes it true for you and no one has any objective basis for saying that your belief is false. Likewise, if I believe the opposite is true, that makes that true for me and no one has any objective basis for saying that my belief is false. So, for example, if Fred believes that global warming is a hoax, that is his truth. If Susan believes that global warming is real, that is her (alternative) truth, and there is no objective fact that decides the matter one way or the other. Both are right.

In philosophy, this view is known as “alethic relativism” (from the Greek word aletheia for “truth or disclosure”). It is also called “relativism about truth.” According to the advocate of this view, those who believe in objective truth are mistaken. The real truth about truth is that truth is relative to each person. There is no such thing as an objective truth that is the same for everyone or that can be accessed by everyone. Of this the alethic relativist is certain.

Relativism about truth sounds exciting to many today, especially to those who have an adversarial attitude toward traditional ideas. The claim that truth is relative can be found, in one form or another, in the writings of philosophers who call themselves “postmodernists.” It can also be found in the writings of those multicultural theorists who copy their basic premises from relativistic postmodernist philosophy. Some of these multicultural theorists go further and relativize truth not to each person but to each racial or ethnic group. If one group believes such and such, then that makes such and such true for that group and the group’s belief cannot be criticized by anyone outside the group for there is no objective fact of the matter that is the same for everyone across all groups. If another group believes that so and so, then that makes so and so true for that group, and that group’s belief cannot be criticized by anyone outside that group (for the same reason). Each group, on this view, has a unique perspective that cannot be assessed or criticized on objective or rational grounds by members of another group.

However, whether in the individual or group form, relativism about truth has severe problems. When the relativist asserts that truth is relative, isn’t he making an objective claim about the nature of truth? Isn’t he saying that (being relative) is the way truth really is—“really is” in a non-relative way? Isn’t he saying that, in fact, truth is relative and we all should agree? In other words, isn’t the relativist in effect claiming that it is objectively true for all of us that truth is relative? If so, isn’t he contradicting himself? But if a theory cannot even be asserted without self-contradiction, why believe it?

Furthermore, if the relativist gives us reasons to believe that truth is relative—in hopes we will see the light and agree on the basis of common grounds—doesn’t that contradict his claim (that truth is relative)? For common reasons given for a view—reasons available to all–would have to be nonrelatively true, wouldn’t they? But if no good reasons can be given for the view, then why believe it?

The question, What is objective truth? is examined in metaphysics, the branch of philosophy that seeks a rational account of the most fundamental aspects of reality. (We’ll examine the concept of objective truth in a moment.)

The concepts of truth and knowledge are closely related. When we say that someone “knows” something, for instance, “Pat knows that the moon has mountains,” we ordinarily mean, in part, that the claim said to be known (in this case, the proposition that the moon has mountains) is true in an objective sense. As we will see in more detail in a moment, we also ordinarily suppose that the knower has a sufficient reason to believe that the claim is true. It follows that if objective truth does not exist, then neither does knowledge in the traditional sense of the word.

It should be no surprise, then, that those who deny the existence of objective truth usually also reject the traditional concept of knowledge. “Knowledge with a capital K is a myth,” some say. “Nobody really knows anything. All we have are opinions, and one opinion is as valid as any other.” Those who make this claim usually sound so confident that they give the impression they really know what they are talking about.

Time for another definition. A skeptical person is someone who is hard to convince. A skeptic with respect to a particular subject is someone who is hard to convince on that subject. A religious skeptic, for instance, is hard to convince on matters of religion. In philosophy the denial of all knowledge is called “global skepticism.”

If the global skeptics are correct, knowledge as we normally use the term is a total mirage. Which raises an interesting question. If knowledge does not really exist, then what are people doing when they claim to know something? The answer some postmodernist global skeptics give echoes an idea first stated by global skeptics in ancient Greece who debated and opposed Socrates. A claim to knowledge, they claim, is in reality just a sinister power grab. When someone claims to know something, they are simply trying to bully you into agreeing with them. In other words, they are trying to get their way. In most cases, they are attempting to gain power over you. As some of the ancient Greek Sophists put it, victory, not truth, is the hidden goal of every claim to knowledge. Or so say many critics of the traditional concept of knowledge.

However, if the global skeptics are right, then isn’t their confident assertion—that a claim to knowledge is merely a disguised power grab unrelated to real truth—also a disguised power grab unrelated to real truth? When they try to convince us to agree with them, aren’t they merely doing what they claim to hate? Isn’t their skepticism also nothing but a sinister power grab? If it is, why believe it?

Furthermore, if all we have are unsubstantiated opinions, and if one opinion is no better than another, then the postmodernist rejection of the traditional notion of knowledge is just one more unsubstantiated opinion. If so, then why believe it? These critics of tradition can give no solid reason for their view without contradicting themselves. But if postmodernist relativism cannot support itself without contradicting itself, then it is an irrational viewpoint unworthy of a serious critical thinker.

I meet students every quarter who subscribe to these relativistic and skeptical postmodernist views. The traditional concepts of objective truth and traditional knowledge are under attack today in some quarters of the academic world. Knowledge and truth, many academics now believe, are collective delusions, throwbacks to primitive times, or (worse) mind-control tools imposed by the ruling class, “the man,” or the establishment. Are these critics of tradition right? Or can the traditional notions of truth and knowledge be defined in plausible terms and rationally defended in the twenty-first century? That is the question before us in this chapter.

For clarification we’ll begin with the underlying metaphysical question, What is truth? After that we’ll turn to epistemology (from the Greek word episteme for “knowledge”)—the philosophical study of the nature, scope, and limits of knowledge. What exactly is knowledge? How (if at all) does it differ from mere opinion? What (if anything) can we know? What is the relationship between knowledge and truth? Socrates, as recorded in Plato’s dialogues, was the first to ask these questions in a philosophical context and to propose precise answers within a systematic theory of epistemology.[endnoteRef:2] His student Plato was the first to examine them in depth and work out a unified theory in written form. The ancient Greeks are the founders of epistemology as an academic subject. [2: Stated most clearly in Plato’s Meno and in his Theaetetus. ]

2. What Is Truth?

The most widely held definition among philosophers today is the account first expressed by Socrates in the dialogues of Plato and stated more formally in the logical works of Aristotle:

A proposition is true if it accurately corresponds to the facts; it is false if it does not.

Truth, in short, is correspondence with the facts. In philosophy, this is known as the correspondence theory of truth.

Notice the way each of the following true statements accurately corresponds to, or specifies, the relevant facts:

· There are craters on the Moon.

· The White House is located in Washington DC.

And notice the way the following false statements fail to correspond:

· There are large cities with skyscrapers on the Moon.

· The White House is located in Minnesota.

Although most philosophers throughout history have thought that the correspondence theory of truth is simply common sense made precise, two alternative theories have been proposed. According to the coherence theory of truth, what makes a proposition true is that it belongs to a coherent system of propositions. A system of propositions is coherent if its members are (a) logically consistent and (b) stand in a sufficient number of explanatory and logical relations to one another. A well-written novel is an example of a coherent system of propositions.

However, the coherence theory faces an objection that nearly all philosophers find decisive. It is possible to specify two equally coherent systems of propositions that are related in such a way that one contradicts the other. Since the two systems are contradictory, they cannot both be true. Yet both are equally coherent. If so, then truth cannot be mere coherence.

A second alternative to correspondence is the pragmatic theory of truth. According to this theory, truth is usefulness. A proposition is useful if belief in the proposition serves a human purpose. The pragmatic definition also faces an objection that most philosophers find fatal. Some propositions are useful in the pragmatic sense, even though they are clearly false. Hitler’s racial theories, for example, were useful to him in the sense that people who believed them helped him attain power, yet his theories have been proven false. But if a theory can be useful and yet false, then truth is not simply usefulness. For many reasons, the correspondence theory remains the mainstream, as well as the commonsense, view.

Objective and Subjective Truth Contrasts are always helpful when learning an abstract concept. Philosophers draw a distinction between objective and subjective truth. Roughly, a

truth is objective if that which makes it true—its “truthmaker”–is an objective fact or feature of reality—a fact that exists on its own, independently of what anyone may or may not believe. A truth is subjective if that which makes it true is a subjective aspect of a person’s consciousness. Suppose I believe that strawberry ice cream tastes better than vanilla ice cream, and I state my opinion. My opinion is subjectively true because it is true by virtue of my personal or subjective sense of taste. It is not true (that strawberry ice cream tastes is better than vanilla) for those who dislike the taste of strawberry, and it will no longer be true for me if my taste changes. There is no objective fact of the matter, existing independently of my subjective taste, that makes the statement true. That which makes my opinion true for me is my inner sense of taste—a subjective aspect of my consciousness alone. An objective truth, on the other hand, is true by virtue of the facts, which are what they are regardless of what people may or may not believe or like. For example, it is objectively true that the moon has mountains. This proposition will remain true even if a dictator takes control of the world and convinces everyone that the surface of the moon is as smooth as silk. The proposition (that the Moon has mountains) will remain true even if everyone believes it is false, for its truthmaker is a fact about the Moon—a fact that exists independently of what people may or may not believe. In this way, some truths are objective, and some are subjective. On the standard interpretation, the correspondence theory of truth is a theory of objective truth.

The claim “Everything is subjective” must be nonsense, for it would itself have to be either subjective or objective. But it can’t be objective, since in that case it would be false if true. And it can’t be subjective, because then it would not rule out any objective claim, including the claim that it is objectively false.” — Thomas Nagel, The Last Word

3. What Is Knowledge?

There are many different kinds of knowledge. We may say that a person “knows” how to drive a car. This is practical, or how-to, knowledge. We say that a carpenter “knows” how to build a house. Call this “craft-knowledge.” We often say that one person “knows” a second person. This is acquaintance knowledge. There is also “public knowledge” (information that has been made public) and “common knowledge” (facts known by most people).

But we also say things like “I know that there are an infinite number of prime numbers” and “I know that the moon has craters.” Epistemologists call this “propositional knowledge” because a proposition or statement (rather than a skill, a person, etc.) is that which is known.[endnoteRef:3] In Plato’s Dialogues, Socrates seems quite interested in craft knowledge. However, when he works out a strict definition, his focus is propositional knowledge. This is understandable, since the context in the dialogues is intellectual. From here on, by knowledge we’ll mean the propositional kind. So, what exactly is propositional knowledge? [3: Recall that a proposition is not the same thing as a sentence. Two different sentences can express one and the same proposition. Technically, a proposition is the claim expressed by a declarative sentence. You won’t go wrong if you think of a proposition as the meaning of a declarative sentence. When two different sentences mean the same thing, they express the same proposition. ]

In his Dialogues, Plato portrays Socrates seeking an answer to the following question: When is it correct to say that someone “knows” something? Socrates’s first observation, put in modern terms, is that we would not ordinarily say a person knows that some proposition P is true if the person does not believe that P is true, i.e., corresponds to the facts. (Socrates and Plato accepted the correspondence theory of truth.) Surely believing P is a necessary condition for knowing P. If I sincerely state that I do not believe that whales are mammals, then it would not be correct to say that I “know” that whales are mammals.

Next, Socrates observes, we do not ordinarily say that a person knows some proposition P if, in fact, P is not true. For a contemporary example, some people actually believe that the earth is flat. They claim to have credible evidence. However, the earth is not flat. This is why we do not say, “They know that the earth is flat.” Rather, we say, “They believe that the earth is flat.” The truth of the proposition said to be known is clearly a necessary condition for the presence of knowledge.

Finally, we do not normally say that a person “knows” that some proposition P is true unless the claim that P is true is anchored to reality by good reasoning showing that P is certainly or at least very likely true. For example, imagine that during a drawing I believe that Ann will win the door prize, and she, in fact, does. However, suppose that I had no reason to believe that she would win; my belief was a lucky guess. In that case we would not say that I “knew” (beforehand) that she would win, for guesses are not justified by credible evidence. In general, a true belief only rises to the level of knowledge if it is tethered to reality by reason, that is, by an argument making it certain or very likely that the proposition said to be known is indeed true.

In sum, three conditions need to be satisfied before we ordinarily say that a person or “subject” S knows that a proposition P is true:

1. S believes that P is true. (This is called the “belief condition.”)

1. The proposition P is true. (This is called the “truth condition.”)

1. S has an adequate justification for believing that P is true, where the justification for a claim P is “a sufficiently strong reason or justification for thinking that P is true.”[endnoteRef:4] (This is called the “justification condition.”) [4: Laurence Bonjour, Epistemology: Classic Problems and Contemporary Responses (New York: Rowman and Littlefield, 2010), 15.]

The epistemologists Ernest Sosa and Laurence BonJour summarize all three conditions compactly in the following words: “Ever since Plato it has been thought that one knows only if one’s belief hits the mark of truth and does so with adequate justification.”[endnoteRef:5] [5: Laurence BonJour and Ernest Sosa, Epistemic Justification: Internalism vs. Externalism, Foundations vs. Virtues (Oxford: Blackwell, 2003), 1.]

For example, Jane knows that Jupiter’s atmosphere is mostly hydrogen and helium only if (a) she believes that the atmosphere of Jupiter is mostly hydrogen and helium, (b) it is true that the atmosphere of Jupiter is mostly hydrogen and helium, and (c) she has adequate justification for her belief in the form of a sufficiently strong reason for thinking that her belief is true.

Socrates and Plato argued that the belief, truth, and justification conditions are jointly sufficient and individually necessary for the presence of knowledge. Some terminology is required before this will be precise. A condition is a sufficient condition for X if its presence all by itself guarantees X. For example, jumping in Green Lake is a sufficient condition for getting wet. A condition is a necessary condition for some X if it is a requirement for X, which means that without it, X cannot exist. For example, oxygen is a necessary condition for human life. Here’s a shorthand way to think of it: a sufficient condition is a guarantee; a necessary condition is only a requirement. Notice that oxygen is necessary but not sufficient for life (you need more than oxygen), while jumping in a lake is sufficient but not necessary for getting wet (there are other ways to get wet).

So, the Socratic and Platonic claim is that if all three conditions are satisfied, knowledge is present (the person knows that P), but if even one condition is not satisfied, knowledge is not present (since each condition is required). Because this was the first philosophical theory of knowledge, it is also called the “classical account of knowledge.” Today it is also sometimes called the “JTB theory of knowledge” because it may be summarized with the slogan that knowledge is “justified true belief.”

The justification condition is the only one of the three that is difficult to understand. People can have many different kinds of justifications for holding a belief. Someone might believe a proposition simply because he finds the belief comforting—although the person might not realize that comfort is the unconscious reason he accepts the belief. The belief serves as an emotional crutch. The reverse, of course, is also possible: someone might reject a proposition simply because he doesn’t want it to be true. These are emotional justifications for belief.

Some beliefs are held for self-serving reasons. For instance, someone benefits greatly from a certain economic system, and this—rather than a reasoned argument–is the real reason why the person believes that the system is best.

A belief might also be accepted because it is useful—although the believer might not realize that this is the unconscious reason he accepts the belief. This would be a pragmatic reason to accept a belief.

Emotional, self-interested, and pragmatic justifications do not satisfy the JTB justification condition for knowledge because neither kind of justification is intrinsically related to the goal of the cognitive enterprise, which is the attainment of objective truth. The fact that believing P comforts you or makes you happy does not make it likely that P is true. Just because you want P to be true, or hope that P is true, does not make it certain, or even likely, that P is true. A belief could be useful and yet false. (Hitler’s racial beliefs, for instance.) In short, emotional, self-interested, and pragmatic justifications of a belief do not satisfy the JTB justification condition for knowledge because there is no intrinsic connection between unexamined emotions, feelings, ego, self-interest, or usefulness, and actual truth.

Today epistemologists call the type of justification required for knowledge “epistemic justification” to distinguish it from other kinds of justification. Epistemic justification consists in reasoning that make it certain or likely to a sufficient degree that the belief said to be known is true. Epistemic justification is thus reasoning that is truth-conducive. As BonJour, a leading contemporary epistemologist, puts it, epistemic justification “increases or enhances to an appropriate degree . . . the likelihood that the belief is true.”[endnoteRef:6] This is appropriate because (again) only this kind of justification is aimed at the goal of cognition, namely, the attainment of truth. [6: Bonjour, Epistemology, 35.]

For a plain example, my (epistemic) justification for believing that it is snowing outside right now is that (a) I clearly seem to see snow coming down, (b) my senses are not impaired, (c) I am in a lucid frame of mind, (d) I have no reason to think someone is tricking me, and (e) I already know what snow is. For another example, my justification for believing that the Beatles’ last concert was at Candlestick Park, San Francisco, on August 30, 1966, is that (a) I read an account in a reputable book written by a trusted author, (b) the book contained documentation, and (c) I have no reason to doubt its accuracy. The supporting reasons for both beliefs make it very likely, if not certain, that each belief is true. Thus, in each case I know.

The Value of Knowledge

Reflecting on some of the lessons he had learned in life, Socrates once said:

And isn’t it a bad thing to be deceived about the truth, and a good thing to know what the truth is? For I assume that by knowing the truth [we] mean knowing things as they really are.[endnoteRef:7] [7: See Plato’s Apology in the second part of the Interlude “Socrates at Work.” ]

Do you agree with Socrates? Isn’t knowledge valuable? And isn’t it valuable because it puts us in touch with reality, which we all seek? Don’t we value truth over falsehood, reality over illusion?

4. Why Accept the JTB Theory?

Socrates and Plato based their theory of knowledge on observations of the way we use the verb to know in propositional contexts. With this in mind, let’s briefly examine the conditions one by one. An obvious reason to accept the belief condition is that we do not ordinarily say that someone “knows” that a proposition P is true if the person does not believe that P is true. Certainly, believing that P is true is a necessary condition—a requirement—of knowing that P is true.

Why accept the truth condition? The main reason is that we ordinarily do not dignify a belief by calling it “knowledge” if the belief is false. For example, if someone claimed to know that George Washington is still president today, we would reply, “That may be your belief or your opinion, but it is not genuine knowledge.” (And the reason the belief is not knowledge is that it is false, right?) Certainly, truth is a necessary condition if a belief is to qualify as real knowledge.

Turning to the third condition, imagine that a fortune-teller reads a crystal ball and predicts that it will snow tomorrow. Suppose that she believes her own prediction and her prediction comes true. Nevertheless, we would not say she knew that it would snow. For she had no good reason connected to reality to conclude that it will snow. She just made a lucky guess, and a lucky guess is not genuine knowledge. Lacking justification, her true belief does not count as real knowledge. In everyday discussion, a true belief only rises to the level of knowledge when it is solidly anchored to reality by reasoning that makes it certain, or at least very likely, that the proposition believed really is true. We know that there are craters on the dark side of the moon because we have good evidence solidly linking the proposition to reality.

I mentioned but did not examine the distinction between opinion and knowledge. With the JTB theory in hand, that distinction can now be clarified. An opinion (or a guess or a hunch) is a belief that does not rise to the level of knowledge because it is not solidly grounded in reality by a sufficiently strong reason to believe it is true. In other words, an opinion is not real knowledge because it is not epistemically justified.

5. Objections and Replies

Some argue against the belief condition by pointing out that we sometimes say, “I know it, but I don’t believe it.” They suppose that statements such as this show that knowing does not require believing. However, when someone makes such a statement, the person normally does not intend to be taken literally. It’s just a way of saying, “I’m astonished.” The objection fails.

A common objection to the truth condition runs like this: “In the Middle Ages, it was common knowledge that the sun circles the earth. But the proposition (that the sun circles the earth) was false; therefore, we can know that which is false.”

This argument is flawed. We misuse the word knew if we say that people in the Middle Ages “knew” the sun circles the earth. It is more accurate to say that in the Middle Ages, people claimed to know that the sun revolves around the earth. It would be even better to say, “In the Middle Ages, it was commonly believed that the sun circles the earth.”

Some have argued that the justification condition is not needed. They observe that people sometimes make lucky guesses—based on no grounds or evidence whatsoever—and then say, “See, I knew it!” It follows, they conclude, that justification is not a necessary condition for knowledge. The problem is that examples such as this are not cases of genuine knowledge. People can say that they have knowledge, but saying so doesn’t make it so. In the absence of any grounds or evidence, such cases do not constitute real knowledge.

Let’s now return to the global skeptics who claim that genuine knowledge doesn’t exist. All we have, they say, are unjustified opinions (and one opinion is as valid or true as any other). But isn’t it a matter of common sense that many beliefs are epistemically justified (while many simply are not)? Aren’t we justified in believing that there are craters on the moon? That electrons have a negative charge? That basketballs are bigger than atoms? And that many diseases are caused by viruses and bacteria? Don’t we know these things? Don’t we know them because we have very good reason to believe that they are true?

And aren’t the following three beliefs epistemically unjustified? Cancer is caused by witches. A secret civilization of green giants inhabits the center of the earth. The sun orbits the moon. Can we give up the traditional notions of objective truth and knowledge and still make sense of our world?

Furthermore, if the claim that …

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