What Truth Is—and Isn’t

It is perhaps surprising that something so widely discussed should be so hard to grasp. The challenge lies in its multiplicity of definitions (what are we talking about when we talk about truth?), the question of authority (who decides what is true?), as well as our pressing need to simply get on with life; even if it’s true that little can be conclusively proven, as some argue, it’s necessary at some level to make a presumption and proceed on that basis.

And yet we cannot do without truth, or some version of it. As philosopher Simon Blackburn says, “to believe anything at all is itself to take a stand on its truth. And we cannot do without belief, since planning and acting in the world requires it.” The issue is further complicated by a widespread and familiarly human reluctance to relinquish cherished beliefs, even if they’re shown to be unfounded.

More recently, the subject has regained popular attention with the coinage of post-truth, the idea that adherence to facts and rational enquiry has been demoted in favor of populist and often emotion-driven decision making. From one US aide’s reliance on “alternative facts” to the general population’s growing suspicion of “experts,” the question about the identity and value of truth has become a major international issue.

All in all, there appears to be a demonstrable sense that—though we have passed through the ages of renaissance, enlightenment, and rationality—most of us continue to exist with the same unclear conceptions of truth that humans have had since the beginning.

“All too often people who think they have been denied trustworthy sources of information take refuge in believing whatever they would like to be true.”

Truth: An Abstract?

Widespread consternation with the idea of post-truth has generated a slew of books on the topic. One of these, On Truth, is by Simon Blackburn, a noted philosopher and fellow of Trinity College, Cambridge. It’s the third book whose cover bears both his name and the word truth, and it comes more than a decade after his excellent Truth: A Guide for the Perplexed (2005). This earlier book, though written in what he admits was a different context (he addressed postmodern relativism rather than post-truth), opens with a statement that remains strikingly familiar: “It is easy to feel frightened. . . . The beliefs and faiths that move people to behave as they do are opaque to others; as we read or watch the news, lunacy together with mutual suspicion and contempt seem to be the order of the day.”

The slimmer On Truth takes a slightly different approach and is split into two sections. First, Blackburn outlines five major classical conceptions of truth: correspondence, coherence, pragmatism, deflationism and Tarski’s semantic theory. Writers and philosophers over the millennia have outlined and wrestled with these ways of identifying what can be true. This section is essentially a handbook, and a useful one. It holds enormous value to readers, who may recognize echoes of their own rationality (and that of others) in every method, which begs personal questions about whether such a hodgepodge of approaches can be legitimate. He gives a sense of his own leaning toward deflationism, while admitting its weaknesses. His is an evenhanded approach, with an understanding that the philosophical exploration remains a work in progress.

The second half of the book takes a fresh tack, addressing arenas that have historically proved trickier grounds for truth: taste, art, ethics, reason, religion and interpretation. In these areas relativism—that is, one view is as worthy as another—thrives, if only for pragmatism’s sake. For instance, we may think our friend has terrible musical taste, but we prefer to preserve the relationship rather than harangue him or her with an absolutist argument about tacky pop music. Blackburn cites the Latin maxim de gustibus non est disputandum, “tastes are not to be disputed,” as an illustration that these have not traditionally been seen as areas in which truth applies at all.

He is right to question that, though, because in practice we often speak of interpretations in terms of truth. Critics talk of good art and bad art, while the idea of “right” and “wrong” ways of living (described by some as outdated) is widely applied across all cultures. He tackles each area with increasing rigor, ultimately arguing that “things become much clearer when we stop dealing with truth in the abstract and look at the ‘particular go’ of it. We then understand why we want it: it is because we do not want people thinking badly, faltering along foolish paths of inference, and we need to signal what counts as doing so.”

This is a practical and human-centered perspective. He approaches religion in the same way, as a man-made construct that must be measured by the perceived good it can bring to humanity. He recognizes its functional benefits; for instance, as a sort of “tribal cement,” and as a consolation. He ultimately argues that religious practice, if it “seeks a cousinship with ethics and aesthetics,” must be measured by the same standards as those are. If the results of this test are “positive,” he writes, “then at the very least there is nothing to oppose or complain about.” He is skeptical that it can attain this standard, which is not surprising given religion’s problematic legacy in human history.

Blackburn’s approach is more about methods than conclusions. He writes, “Instead of facts first, with method analyzed in terms of its contribution to fact, we look at the methods first, and then describe fact in terms of the ideal endpoint (which we may never reach) of satisfactory applications of method.”

This is, in effect, an idealized empirical method. The history of human error, from the flat-Earth theory to the idea that the sun orbits the earth, makes this attractive, though it must be a little dispiriting to anyone with an absolutist urge, or anyone with a strong belief in the inexorability of human progress.

Finding the Truth of the Matter

Neuroscientist Daniel Levitin takes a similarly practical approach in A Field Guide to Lies and Statistics (originally published as A Field Guide to Lies). This is a book purportedly for everyone, designed to arm people in a world where “it is becoming increasingly hard to tell what’s true and what’s not, to sift through the various claims we hear and to recognize when they contain misinformation, pseudo-facts, distortions, and outright lies.” Levitin outlines a series of basic logical processes, statistical tricks and fundamental questions we ought to be asking ourselves whenever we encounter a piece of information.

His examples and approaches range from the exceedingly basic, which he claims “should not be beyond the ability of most fourteen-year-olds,” to rather more complex statistical analyses. He scrutinizes political polls, media headlines and medical claims, including a since-discredited allegation that autism is caused by vaccines, demonstrating how anyone with access to a library or the Internet can do the same.

“Many people think, ‘If I found it online it must be true.’ With no central authority charged with the responsibility of monitoring and regulating websites and other material found online, the responsibility for verifying claims falls on each of us.”

He gives a touching account of how he and his family assessed, with logical analysis, the various treatment options available to their beloved dog when it developed a tumor. His point is that clear thinking can function even in situations of high emotion.

One of Levitin’s foundational models is Bayes’s theorem, named after 18^th-century statistician and Presbyterian minister Thomas Bayes. His mathematical formula is widely used for calculating conditional probabilities, especially when new information might alter our understanding of a given subject.

Application of the theory can lead to counterintuitive results. Levitin recounts a situation where it was found that, if a woman has breast cancer, a mammogram will indicate it 90 percent of the time. One doctor interpreted this as meaning that positive test results should automatically necessitate treatment, with devastating results; Bayes’s theorem reveals that, even with a positive mammogram, the probability of actually having breast cancer is only 9.4 percent. The rarity of the condition, and the relative inaccuracy of the test, makes the initial statement much less significant than it at first seems.

What’s curious is, when laid out, how obvious this all seems. There is very little that surprises in these pages, whether in the models he relates or in the examples he uses. This is no doubt partly the point: none of this is difficult, and most legitimate statements are unexceptional. Levitin’s aim is to present these principles in an unintimidating fashion.

The only really surprising aspect is that such a book should be necessary at all. It is, however, because we see people—including ourselves—misinterpreting and falling for statistical deceptions and distortions all the time. Levitin points out that we “have a tendency to apply critical thinking only to things we disagree with.” It is clearly not his purpose to examine why this happens, nor to speculate how likely it is that this will change; and yet it is a subject worth pondering.

Who Can You Trust?

What both authors presume, at some level, is that we humans are capable of uncovering truth at all. This isn’t a universal assumption: ancient Greek skeptic Carneades, for instance, appeared to question our ability to acquire it, while the paradox “I know that I know nothing” (widely, though perhaps mistakenly, attributed to Socrates via Plato) suggests a similar point. This skepticism echoes biblical wisdom too. The prophet Jeremiah wrote that “it is not in man who walks to direct his own steps”; the playful irony of a man walking without the ability to navigate is a nod to our pragmatic need to act, as Blackburn writes, while also suggesting that we do so while effectively blind.

Blackburn and Levitin’s emphasis on method is a refreshing recognition that humans have a poor record when it comes to conclusions. It’s an approach that steers away from the practice of starting with an assumption, though both recognize value in doing so in certain circumstances. It’s worth asking, however, whether we can be trusted to recognize those circumstances. For instance, a young boy is unlikely to understand the process of rapid oxidation in combustion, so he needs to begin by trusting the conclusion given to it by experts—perhaps parents or a teacher—that he shouldn’t put his hand in the fire.

This doesn’t apply only to children, of course. We all must in many areas rely on conclusions supplied by people who know what they’re talking about. But the recent rise of emotion-led post-truth decisions, and the tendency toward rejecting “experts,” suggests that even adults are not particularly prepared to do so.

“A big part of the problem here is that the human brain often makes up its mind based on emotional considerations, and then seeks to justify them. And the brain is a very powerful self-justifying machine.”

Six Dominant Ideas

Ideas can be powerful. If they are good, we all benefit; but bad ideas can have disastrous effects. In this series Vision looks at six prominent ideas of our time—concepts that animate our thinking and the language we all use. Yet each one is fundamentally flawed.

One idea that neither author tackles is that of a divine expert, which is at the heart of many religions. Blackburn views religion as potentially useful, so long as its consequences are practically and verifiably beneficial to humans. He does not, however, assess its usefulness as a source of truth. The Bible expresses information that it alleges is conveyed by God, an infallible being who will not deceive. Years of misinterpretation, heinous misapplication and hypocrisy on the part of many believers have discredited this source for those who are skeptical of its worth. Some of the Bible’s supposed adherents have overreached—for instance, when cult leaders claim divine direction while openly disobeying biblical instructions—while many others have underplayed or outright rejected its value.

The fact is that the Bible offers its own effectiveness test, which is surprisingly akin to Blackburn’s. An Israelite psalmist, for example, urged his listeners to “taste and see that the Lord is good; blessed [i.e., happy] is the man who trusts in Him.” The basic process outlined here—try, then measure—is classic empiricism. But it also requires a form of trust, akin to that of the child who accepts that it’s a bad idea to put its hand in the fire, which even the most atheistic human applies in everyday life.

Levitin writes that “we’ve created more human-made information in the last five years than in all of human history before them.” Ours is an often confusing and bewildering world. It is full of information, claims and counterclaims, arguments and falsehoods, which we each must in some way handle. Despite the persistence of relativist thought, there are many who assert that there is such a thing as a useful conclusion—that truth actually exists. There are also actions and beliefs that are better avoided. As Blackburn writes, “there is no limit to the size of catastrophe that acting on a false belief can bring about.”

Biblical wisdom is attuned to this. It outlines, in basic principles, a way of living, and warns against other ways. Some of it seems self-evident. Some seems inexplicable. But, like the counterintuitive conclusions that clear empirical enquiry can reveal, its benefits come via testing.