The five other sceptical tropes have an entirely different character, and it is at once evident that they indicate quite another point of view and degree of culture as regards philosophic thought; for they pertain more to thinking reflection, and contain the dialectic which the determinate Notion has within it. Sextus Empiricus[206] sets them forth as follows:—
a. The first trope is the diversitude in opinions (ἀπὸ τῆς διαφωνίας), and that not among animals and men, but expressly among philosophers; of this matter we have just spoken above (pp. 349, 350). Sextus, and an Epicurean quoted by Cicero (Vol. I. p. 16), adduce the manifold nature of dogmas, and from this the conclusion is drawn that the one has just as much support as the other. Philosophers and others still make copious use of this sceptical trope, which is consequently in great favour: on account of the diversitude in philosophies, they say, Philosophy has no value, and truth is unattainable because men have thought about it in ways so contradictory. This diversitude in philosophic opinion is said to be an invincible weapon against Philosophy; but the category of difference is very barren, and we have said in the introduction (Vol. I. pp. 17-19) how it is to be understood. The Idea of Philosophy is to all philosophers one and the same, even if they themselves are not aware of it; but those who speak so much of this diversity know as little about it. The true difference is not a substantial one, but a difference in the different stages of development; and if the difference implies a one-sided view, as it does with the Stoics, Epicureans, and Sceptics, in their totality undoubtedly we first reach truth.
b. A very important trope is that of failing into an infinite progression (ἡ εἰς ἄπειρον ἔκπτωσις); by it the Sceptics show that the reason which is brought forward for an assertion itself again requires a reason, and this again another, and so on into infinitude; from this suspension of judgment thus likewise follows, for there is nothing which can furnish a solid foundation. Consequently no permanent ground can be pointed out, for each continues to press further and further back, and yet finally a cessation must be made. In more recent times many have plumed themselves on this trope, and, in fact, it is as regards the understanding and the so-called syllogism (_supra_, pp. 222, 223), a trope of great force. For if deduction from reasons is made the power of knowledge, we must, on the other hand, remember that by so doing we have premises which are quite ungrounded.