I’ve been thinking a lot about the seventh chapter in a splendid book called The Ancients and the Moderns, by a fascinating Boston University professor named Stanley Rosen. I read the book over two years ago, but the ideas of this chapter have since continued to percolate in my brain.

Rosen argues that we need to see a much closer association between two fields of study often thought separate: logic and psychology. At first glance, the two might seem to have little in particular to do with one another. Logic concerns itself with the proper formal relationships between statements in arguments; psychology, with the empirical investigation of mind and behaviour.

But more basically, what are logic and psychology? Both, really, are the study of thought. One might narrow logic down a bit and say it is the study of reasoning; but reasoning is very much a part of psychology’s subject matter as well. Their differences are not in their subject matter. There is certainly a difference in method; but that difference flows from a more fundamental difference between the two.

Namely: psychology (or at least certain branches of it) tells us how we do in fact reason. Logic tells us how we should reason. Psychology tells us about the circumstances under which we do or do not follow the rules of reasoning that logic sets down as proper. Which is to say: logic is a normative discipline. That is, logic, like ethics and aesthetics, is concerned with goodness and value – with what should and should not be the case, not merely with what is and is not the case. The idea of a truth that is better than falsehood, and of the methods to discover that truth, is part of what makes logic possible.

The relationship between logic and psychology, taken in this way, is more or less the relationship between ethics and ethics studies, between the philosophy of science and science studies, or between theology and religious studies as religious studies is very often conceived. The latter member of each pair tells us how we do reason (or act); the former tells us how we should. But where the ideals of science, ethics and theology tell us how to reason within their particular fields of inquiry, logic tells us how to reason in the general case, including all the others.

Logic is a normative discipline – a discipline concerned with value – because it is fundamentally concerned with truth. And it is part of the nature of truth to be a value, to be better than falsehood. To deny the intrinsic value or goodness of truth makes no sense, as I argued before in claiming that truth has a value independent of pleasure.

The normative nature of truth holds true whatever one might understand truth to be. Analytic philosophers most commonly identify three theories of the truth of statements (or more generally propositions): correspondence, coherence and pragmatic. Speaking broadly, on the correspondence theory, propositions are true if they correspond to reality; on the coherence theory, propositions are true if they cohere with other propositions we hold; on the pragmatic theory, propositions are true if they are effective. But what is presumed by all three theories is that truth is a good thing: other things being equal, propositions that correspond to reality or that cohere with other propositions or that are effective are better than propositions that do not do these things. And when this is true of the more limited analytical theories of truth, how much more so of more expansive theories of truth that do not limit themselves to propositions, like those of Augustine or Gandhi. Augustine probably goes the furthest on this point: truth is goodness – which is God.

The fact that truth and logic are normative and value-laden has important consequences. For one thing, it gives the lie to simplistic claims of “value-free” science or social science (including psychology itself). All intellectual inquiry is predicated on at least one value, namely truth itself. More sophisticated defenders of “value neutrality,” like Max Weber, will argue that the scholar of a scientific field needs to put truth above other values – but we must recognize that this argument is itself a value argument, an ethical argument for the importance of truth relative to other values, at least within certain areas of inquiry. The argument that one should place truth above other values is a normative and value-based argument.

Now the discussion above should not imply that all true statements are good statements, or all true things are good things. It is true that outlying areas of Bangkok were recently hit by disastrous floods; it is not good that this happened. The relation between truth and goodness is and must be more complex than that.

The fact that not all true things are good probably seems obvious to anyone who isn’t a philosopher; but it nevertheless poses some problems. For someone like Augustine who identifies truth with goodness, it would seem to be at the very heart of the problem of bad. If truth is goodness, how can there be things that truly exist but are nevertheless bad? Augustine ingeniously deals with this problem (or at least this aspect of the problem) by identifying badness as a lack of the existence of good – in the same way a modern physicist identifies cold as simply a lack of heat. Absolute evil, on his account, looks very much like absolute zero.