Ancient Methods for Judging and Using Testimony Still Valuable Today

Much of what we know, or what we think we know, is based upon testimony. How do I know that Caesar was killed in 44 B.C.? I probably heard it from a teacher who, by virtue of this very position, seemed a trustworthy source. Or maybe I have it on the authority of a reputable book on ancient history. If forced to show the indubitable foundation of my belief about the date of Caesar’s death, I might refer to written testimony from the time, though these too are only reports. It would seem quite strange to reject these sources and demand more proof. After all, I trust the word of others in regards to such recent and non-historical events such as the date of my own birth.

Hearsay, then, is an important source of what we think we know, and has been for thousands of years. We invoke it to convince our friends, just as public speakers and scholars cite studies and the testimony of others to persuade their colleagues and audiences. Knowing how to deal critically with testimony and authority as sources of knowledge is obviously of great value, both for research and for everyday reasoning. What is more: there are some controversial questions on which uncertain knowledge is the best we can get. There are, for example, issues of eternal dispute. Take Lord Tennyson’s contention that it is better to have loved and lost than never to have loved at all. The jury is still out on that one – but citing Tennyson by name might help you console a love-sick friend. And then there are questions a bit less academic. And whether there is life after death is a question on which there are understandably few reports based upon experience – but nevertheless quite a few authoritative opinions. Here and elsewhere, it is useful to have a method to sort the opinions out.

One such method was developed by Aristotle (384-322), who, among many other things, developed guidelines for dealing with opinions in arguments on these and other questions of purely verbal debate. In current parlance, these might be called “academic” questions. This is not completely inappropriate, considering that some form of this practice of argument was surely rehearsed by the students in Plato’s Academy. Aristotle, who was a student in Plato’s Academy, clearly took this part of his “Academic” education quite seriously. He applied it in both natural science and ethics – and he also left us some very important work on the topic of argument itself.

His Topics and Rhetoric both contain parts of a theory of what is acceptable in argumentation and develop the notion of ”acceptable premises”, which Aristotle calls endoxa. In Topics, Aristotle defines endoxa as statements which seem true to all, or to most people, or to all or most of the most reputable experts (Topics A 1, 100 b 21-23). He uses this notion to designate the premises of a certain type of regulated argument called dialectic. The concept of endoxa belongs to his theory and method of good – i.e. successful – dialectical argumentation, which is designed to help the student make arguments that really persuade (or confound) the opponent. But endoxa are also relevant for our everyday use of testimony and authority in general.

A particularly interesting example may be found in Aristotle’s own observation that there are widely differing notions about how to describe weakness of will (in the Nicomachean Ethics, Book VII, Chapter 2). By “weakness of will” Aristotle means the cases in which we act against our better judgment. Take the well-known case of the smoker who knows that smoking is harmful to his health, but cannot quit. What is going on here? Most of us would say that the smoker knows that smoking is bad for him, but smokes anyways – either out of habit, compulsion, or addiction to the substance of nicotine. But there is another interpretation of the pattern of behaviour which we have come to describe as “addiction”. According to this controversial understanding, which was brought forward by Socrates, the smoker does not really know that smoking is harmful for him. At least he doesn’t know this in a meaningful sense of “knowing”: for otherwise he wouldn’t smoke. And so, according to this view, the smoker’s inability to kick the habit is a problem of really learning what is healthy and good and what is not. It does not result from weakness of the will.

So here we have a conflict between what most of us think about addiction, and the theory of a man who was renowned for virtue and self-control, namely Socrates. The matter is hard to decide by reference to the “facts”, because these are coloured by description. For this difficult case and others like it, Aristotle outlines a three-step procedure for dealing with conflicts of opinion and testimony. First, he says, we must lay down the relevant phenomena (in Greek: phainomena) of the topic. By this he means not just all relevant facts, but also frequent and established opinions regarding a certain thing. Secondly, we examine the inconsistencies created from differences of opinion and “resolve the difficulties”. Finally, we must set forth all the relevant endoxa concerning the topic – or if not all, most of them, and the most reputable. At the end of his digression, Aristotle justifies this procedure with the remark: “If the difficulties are solved and the endoxa remain, then the proof will have been sufficient” (1145 b 6-7).

In what sense and in which cases are we to take this procedure to be a kind of proof? What sort of justification does the procedure convey upon its results, the remaining endoxa? Indeed: Under what assumptions can such a procedure be considered a “proof” at all? The answers suggested by Aristotle are interesting and surprising. He believes in the power of consensus, which wields such authority that it may even be used against the claims of experts, not least because it is a more reliable indicator of the truth. But this conviction does not rest on blind trust of mass opinion. It relies rather upon the critical utility of what everyone believes in testing what the experts and “famous people” say. The philosopher Aristotle was apparently of the opinion that even those noted for their virtue or knowledge can be made to answer before the tribunal of what we all think is true.

Political leaders (and scientists) take heed!