The flurry of tweets that followed my last post made it clear that there are quite a few interpretations of the sentence “people believe things just because they are true.” One question that came up was whether or not the distinction between truth and evidence is any use in understanding that sentence. I think it is. But even if it is not, I want to make the broader point that esoteric-seeming distinctions can make a big difference to the success of our interactions with the general public. Here's an illustration. If a tree falls in a wood, and no-one is around to hear it, does it make a sound? Well, if by “making a sound” you mean “producing sound waves,” then the answer is clearly “yes.” On the other hand, if you mean “causing a human to experience a sound” then the answer is clearly “no.” The distinction between producing sound waves and causing aural percepts is not one that most people care about. But if our aim is to give a sensible answer to the question posed, we don't have a choice but to make that distinction. If we don't make the distinction, our efforts to answer the question are likely to be wasted. And if we do, we do not need to do much else in order to reach agreement on an answer. Now imagine we are answering the tree-felling question in a public forum. If we answer “yes,” without making the distinction I mentioned, then we should not be surprised if we are met with howls of protest from those who have tacitly taken “making a sound” to mean “causing a human to experience a sound.” Of course it would be better if our readers made the distinction themselves, exercised charity and common sense, and assumed that we meant “producing sound waves.” But if we don't make the distinction, when it makes such a big difference to the correctness of our answer, then we can hardly complain if our audience does not do so either. Conversly, if we are reading a popular text on tree-felling, and the author asserts that trees don't make sounds when they fall in empty forests, then we should not imagine that their claim is obviously, lamentably wrong. To do so would be to ignore the fact that they are half right. And to do that would be to repeat the author's real error, which was not to answer “no” rather than “yes” but to take the question as one rather than two. Clearly there are many distinctions that are irrelevant to any given question. To answer our question about felled trees, it would not be much use to distinguish between tranverse and longitudinal waves. There are are also an infinite number of weird interpretations of a question, and no matter how careful we are to delimit our answers there is bound to be someone who takes it the wrong way. (Example: many of the commentators on Vanessa Heggie's recent post seemed to think that she was advocating some sort of radical skepticism about science, which was pretty clearly not the point of the post.) Philosophers are the specialists in conceptual distinctions, but we historians have a sense of why distinctions matter in general. Whereas philosophers tease apart the meanings of terms, historians are exquisitely sensitive to the peculiarities of different times, places, people, and episodes. The question “Is there a conflict between science and religion?” is meaningless to the historian in the same way that “Is the world one or many?” is meaningless to the philosopher. The answer to both is, “it depends.” We should also bear in mind that academic study can cloud distinctions that are perfectly clear to non-experts. This does not always reflect well on the experts. Consider the distinction between statements about the world and the world itself. If ordinary people did not make this distinction they would have great difficulty getting through their lives without going mad or getting into terrible accidents. Such people would automatically believe everything they read or heard, since they would not be able to grasp the idea of a false statement. They would live in a state of perpetual puzzlement as they witnessed objects and events that appeared to have no statements attached to them. In their confusion they might even mistake events for statements, wandering into the path of oncoming traffic in the belief that this wordly action is as harmless as the statement “there is oncoming traffic.” Yet it is only a bit of an exaggeration to say that entire academic careers have been built around the denial of the distinction between the world and the things we say about it. Much of what is called the 'Science Wars' could have been avoided if both sides had been more careful to distinguish between the two things. More generally, it has long been fashionable in the humanities to frame new ideas in terms of the erasure of one or other distinction that many people take for granted. There is no shortage of authors who claim to challenge the distinctions between subject and object, fact and fiction, fact and value, fact and theory, theory and practice, art and science, etc. It is a long time since I read a book in science studies that promised to mark out a boundary rather than transgressing one, or to heed a dichotomy rather than interrogating one. I'm not saying that all this distinction-denying is a bad thing. My point is that academic study blinds us to the ubiquity of the distinctions we deny just as surely as it blinds us to the abstruseness of the distinctions that are commonplace in our chosen field. What about the distinction between truth and evidence, which I fussed over in my previous post? Is it esoteric like the one between “producing sound waves” and “causing a human to experience a sound”? Or is it more like the distinction between “statements about the world” and “the world itself,” ie. a commonplace that only sophisticated people fail to grasp? I don't know. But the main message of this post is that it doesn't matter. If the distinction helps us to answer the question at hand then it is worth caring about, no matter how ordinary or esoteric it might be. The question at hand—to get back to the topic of this series—is whether the symmetry principle is right in stating that people do not believe things just because they are true. The aim of my next post is to give a list of distinctions that make a difference to how we answer this question. Expand post.