Vitae philosophorum

Irrefutability is strength in argument so as not to be brought over by it to the opposite side. Earnestness (or absence of frivolity) is a habit of referring presentations to right reason. Knowledge itself they define either as unerring apprehension or as a habit or state which in reception of presentations cannot be shaken by argument. Without the study of dialectic, they say, the wise man cannot guard himself in argument so as never to fall; for it enables him to distinguish between truth and falsehood, and to discriminate what is merely plausible and what is ambiguously expressed, and without it he cannot methodically put questions and give answers.

Overhastiness in assertion affects the actual course of events, so that, unless we have our perceptions well trained, we are liable to fall into unseemly conduct and heedlessness; and in no other way will the wise man approve himself acute, nimblewitted, and generally skilful in argument; for it belongs to the same person to converse well and to argue well, to put questions to the purpose and to respond to the questions put; and all these qualifications are qualifications belonging to the skilled dialectician.

Such is, summarily stated, the substance of their logical teaching. And in order to give it also in detail, [*](Cf. supra,§ 38 note. This distinction between the general and particular treatment is also frequent in Sextus Empiricus: e.g. Pyrrh. Hyp. i. 5 ὁ καθόλου λόγος as opposed to ὁ εἰδικὸς λόγος.) let me now cite as much of it as comes within the scope of their introductory handbook. I will quote verbatim what Diocles the Magnesian says in his Synopsis of Philosophers. These are his words:

The Stoics agree to put in the forefront the doctrine of presentation and sensation, inasmuch as the standard by which the truth of things is tested is generically a presentation, and again the theory of assent and that of apprehension and thought, which precedes all the rest, cannot be stated apart from presentation. For presentation comes first; then thought, which is capable of expressing itself, puts into the form of a proposition that which the subject receives from a presentation.

There is a difference between the process and the outcome of presentation. The latter is a semblance in the mind such as may occur in sleep, while the former is the act of imprinting something on the soul, that is a process of change, as is set forth by Chrysippus in the second book of his treatise Of the Soul (De anima). For, says he, we must not take impression in the literal sense of the stamp of a seal, because it is impossible to suppose that a number of such impressions should be in one and the same spot at one and the same time. The presentation meant is that which comes from a real object, agrees with that object, and has been stamped, imprinted and pressed seal-fashion on the soul, as would not be the case if it came from an unreal object.

According to them some presentations are data of

Another division of presentations is into rational and irrational, the former being those of rational creatures, the latter those of the irrational. Those which are rational are processes of thought, while those which are irrational have no name. Again, some of our impressions are scientific, others unscientific: at all events a statue is viewed in a totally different way by the trained eye of a sculptor and by an ordinary man.