Rhetoric is a counterpart of dialectic.1 Both concern matters that are in some way available to everyone’s discernment; neither is defined by any special knowledge. And so everyone in some sense has a share of both; for everyone, to some degree, attempts to criticize or sustain an argument and to speak in defence or to make an accusation. Of the many, some do these things hit or miss, others through familiarity arising from habit. Since either way is possible, it is clear that these goals could also be achieved systematically. For it is possible to observe the reason why some succeed through habit, others at random; and such, all would agree, is the task of an art.
Now, previous compilers of handbooks on speaking have supplied not even a small portion of the art (proofs being the only artistic element, the rest supplement). They don’t even speak about enthymemes (explicit arguments), which are the body of proof, but they concern themselves by and large with extraneous business. For slander and pity and anger and other such passions are not pertinent to the issue, but directed towards the juror. So that if all trials were conducted as they are in some cities and especially those that are well governed, professional speakers of this sort would have nothing to say! And as it turns out, everybody thinks the laws should say as much, and some even adopt the practice and prohibit speaking off topic, as in the court of the Areopagus.2 And they are right to think this way. One must not mislead the juror, turning him to anger or envy or pity. It would be like making a straight ruler crooked before putting it to use. In addition, it is clear that the only role of the litigant is to make clear whether something is or is not so, whether it happened or didn’t happen. Deciding whether it is significant or insignificant, just or unjust, assuming the lawgiver has not specified, must be left to the juror without instructions from the litigants.
It’s especially fitting, therefore, for well-composed laws, to the extent possible, to make all specifications, and to leave as little as possible to the judges, first because it is easier to find one or a few, as opposed to many, who think clearly and are capable of establishing laws and passing judgement. In addition, law-giving takes place after a long process of consideration, while judgements occur on the spur of the moment, so that it is difficult for judges to determine appropriately what is just and what is advantageous. Most important of all, the judgement of the lawgiver is not given piecemeal, but pertains to the entirety of what will happen in the future, whereas the assembly-man and the juror pass judgement on specific issues in the present, on which they often already have a positive or negative outlook or some personal stake, so that they are unable to observe the truth sufficiently, since their personal pleasure or pain clouds their judgement.
About the rest, as we have said, it is necessary to make the judge the determiner of as little as possible; but as to whether something happened or didn’t, or will be or won’t be, or is or isn’t, it is necessary to leave the matter to those assigned to make the decision. After all, it is impossible for the lawgiver to foresee these things. And if this is so, then clearly those who offer specific guidelines concerning the content of a proem or narrative or any other part are filling their manuals with material outside the subject. For they should not be concerning themselves with anything other than disposing the judge in a certain way. Yet they reveal nothing concerning the proofs based in art, even though this is the means through which one becomes skilled in the handling of enthymemes.
For this reason, although the method for deliberative and judicial speeches is the same, and deliberative topics are more noble and better suited to a public figure than contracts and exchanges, they say nothing about the former, but all strain to present a scientific discourse about judicial speaking, because it is of less use in deliberative oratory to speak outside the topic (because it concerns matters of common interest) and there is less opportunity for mischief. This is because in a deliberative context the person making a decision decides about his own affairs, so that there is no need to demonstrate anything other than that matters are as the speaker giving advice says they are. In court cases, on the other hand, this is not sufficient, but it is advantageous to win over the listener. Judgement is about affairs of others, so that the listeners, looking to their own interest and listening for pleasure, give in to the speakers but do not really judge. That’s why, as I explained before, the law often forbids speaking off topic [in judicial cases], for in deliberative matters, the judges themselves keep sufficient watch.
Since it is clear that a scientific system is one that concerns proofs, and that a proof is a demonstration (for our confidence is strongest when we acknowledge that something has been demonstrated), there is a rhetorical type of demonstration, namely the enthymeme, and this is, to put it simply, the most authoritative of the proofs. The enthymeme, in turn, is a type of syllogism.3 As it is the function of dialectic, as a whole or in one of its subdivisions, to consider every kind of syllogism in a consistent manner, it is clear that whoever is most capable of observing from what and by what means a syllogism comes to be would also be the most skilled at enthymemes, grasping in addition the subject matter of a given enthymeme and their differences from logical syllogisms. For the same faculty is employed in understanding what is true and what resembles the truth, and human beings are naturally and sufficiently inclined towards the truth and for the most part hit upon it. Therefore the person who is skilful in attaining the truth is similarly skilful in attaining what is likely to be true.
In short: other writers of treatises on rhetoric discuss matters outside the subject, and for this reason have inclined towards judicial oratory.
Still, rhetoric is useful, because truth and justice are naturally stronger than their opposites, so that if ever judgements are made improperly, they must have been bested by the latter, which is disgraceful. In addition, with some persons, even if we should possess the most secure sort of knowledge, it is not easy to persuade them merely by speaking thereof. Speech in accordance with [scientific] knowledge aims to provide instruction, but with such people this is impossible. Of necessity (as we also explain in Topics)4 proofs and speeches must be constructed from common knowledge in the case of interaction with the multitude. In addition, it is necessary to be able to argue opposite positions, as with syllogisms, not in order to do so in practice (for one must not argue for what is wrong), but to understand the real state of the case and to be able to refute an opponent who is using such arguments contrary to justice. None of the other arts reasons to opposite conclusions; only dialectic and rhetoric do this, for they are similarly concerned with opposites.
But it’s not the same with regard to the underlying subject matter. To put it simply, what is true and better is naturally easier to demonstrate and more plausible. In addition, it would be a bizarre state of affairs if it were shameful to be unable to defend yourself with your body, but not shameful to be unable to do so through language. After all, language is more particular to human beings than use of the body. But if it’s objected that someone using such power of language unjustly could do great harm, the claim applies generally to all good things, except virtue, and especially to those that are most useful, for example strength, health, wealth or position of commander. The person who deploys these advantages in a just manner provides the greatest benefit; if unjustly, he does the greatest harm.
Clearly, rhetoric, like dialectic, is not limited to any one type of subject. It is useful; its task is not to persuade but in each instance to identify the actual means of persuasion. In this respect it resembles the other arts, for example medicine, the task of which is not to create health but to promote it as far as possible (for even those who are unable to recover health can still be treated properly). In addition it is the task of rhetoric to identify both the real and apparent means of persuasion, as it is of dialectic to identify the real and apparent syllogism. For sophistry is defined by moral intent, not ability.5 In contrast, one can be a rhetorician on the basis of knowledge and moral intention, while a dialectician is defined by ability, not moral intent.
Let us now try to describe the system itself, explaining how and by what means we will be able to attain our objectives. Having established our definition, let us proceed, starting, as it were, from the beginning once again. Let rhetoric be the power of observing in each instance the possible means of persuasion. For this is the task of no other art. For each of the others can instruct and persuade regarding its own subject matter, for example medicine about health and sickness, geometry about the properties of magnitudes, arithmetic about numbers, and similarly the rest of the arts and sciences. But rhetoric seems to be able to find the means of persuasion regarding any given topic, so to speak, which is why we say that its technique is applicable to no particular or limited type of topic.