_The Five Tropes._
The later Sceptics, however, teach the following five Tropes 164
of [Greek: epochê]: first, the one based upon contradiction;
second, the _regressus in infinitum_; third, relation; fourth,
the hypothetical; fifth, the _circulus in probando_. The one 165
based upon contradiction is the one from which we find, that in
reference to the thing put before us for investigation, a
position has been developed which is impossible to be judged,
either practically, or theoretically, and therefore, as we are
not able to either accept or reject anything, we end in
suspending the judgment. The one based upon the _regressus 166
in infinitum_ is that in which we say that the proof brought
forward for the thing set before us calls for another proof, and
that one another, and so on to infinity, so that, not having
anything from which to begin the reasoning, the suspension of
judgment follows. The one based upon relation, as we have 167
said before, is that one in which the object appears of this
kind or that kind, as related to the judge and to the things
regarded together with it, but we suspend our judgment as to
what it is in reality. The one based upon hypothesis is 168
illustrated by the Dogmatics, when in the _regressus in
infinitum_ they begin from something that they do not found on
reason, but which they simply take for granted without proof.
The Trope, _circulus in probando_, arises when the thing 169
which ought to prove the thing sought for, needs to be sustained
by the thing sought for, and as we are unable to take the one
for the proof of the other, we suspend our judgment in regard to
both. Now we shall briefly show that it is possible to refer
every thing under investigation to one or another of these
Tropes, as follows: the thing before us is either sensible or
intellectual; difference of opinion exists, however, as to what
it is in itself, for some say that only the things of sense 170
are true, others, only those belonging to the understanding, and
others say that some things of sense, and some of thought, are
true. Now, will it be said that this difference of opinion can
be judged or cannot be judged? If it cannot be judged, then we
have the result necessarily of suspension of judgment, because
it is impossible to express opinion in regard to things about
which a difference of opinion exists which cannot be judged. If
it can be judged, then we ask how it is to be judged? For 171
example, the sensible, for we shall limit the argument first to
this--Is it to be judged by sensible or by intellectual
standards? For if it is to be judged by a sensible one, since we
are in doubt about the sensible, that will also need something
else to sustain it; and if that proof is also something
sensible, something else will again be necessary to prove it,
and so on _in infinitum_. If, on the contrary, the sensible must
be judged by something intellectual, as there is disagreement 172
in regard to the intellectual, this intellectual thing will
require also judgment and proof. Now, how is it to be proved?
If by something intellectual, it will likewise be thrown
into _infinitum_; if by something sensible, as the intellectual
has been taken for the proof of the sensible, and the sensible
has been taken for that of the intellectual, the _circulus in
probando_ is introduced. If, however, in order to escape 173
from this, the one who is speaking to us expects us to take
something for granted which has not been proved, in order to
prove what follows, the hypothetical Trope is introduced, which
provides no way of escape. For if the one who makes the
hypothesis is worthy of confidence, we should in every case be
no less worthy of confidence in making a contrary hypothesis. If
the one who makes the assumption assumes something true, he
makes it suspicious by using it as a hypothesis, and not as an
established fact; if it is false, the foundation of the
reasoning is unsound. If a hypothesis is any help towards a 174
trustworthy result, let the thing in question itself be assumed,
and not something else, by which, forsooth, one would establish
the thing under discussion. If it is absurd to assume the thing
questioned, it is also absurd to assume that upon which it
rests. That all things belonging to the senses are also in 175
relation to something else is evident, because they are in
relation to those who perceive them. It is clear then, that
whatever thing of sense is brought before us, it may be easily
referred to one of the five Tropes. And we come to a similar
conclusion in regard to intellectual things. For if it should be
said that there is a difference of opinion regarding them which
cannot be judged, it will be granted that we must suspend the
judgment concerning it. In case the difference of opinion 176
can be judged, if it is judged through anything intellectual, we
fall into the _regressus in infinitum_, and if through anything
sensible into the _circulus in probando_; for, as the sensible
is again subject to difference of opinion, and cannot be judged
by the sensible on account of the _regressus in infinitum_, it
will have need of the intellectual, just as the intellectual has
need of the sensible. But he who accepts anything which is
hypothetical again is absurd. Intellectual things stand also 177
in relation, because the form in which they are expressed
depends on the mind of the thinker, and, if they were in reality
exactly as they are described, there would not have been any
difference of opinion about them. Therefore the intellectual
also is brought under the five Tropes, and consequently it is
necessary to suspend the judgment altogether with regard to
every thing that is brought before us. Such are the five Tropes
taught by the later Sceptics. They set them forth, not to throw
out the ten Tropes, but in order to put to shame the audacity of
the Dogmatics in a variety of ways, by these Tropes as well as
by those.