(Ἀγρίππας), a sceptical philosopher, only known to have lived later than Aenesidemus, the contemporary of Cicero, from whom he is said to have been the fifth in descent. He is quoted by Diogenes Laertius, who probably wrote about the time of M. Antoninus. The "five grounds of doubt" (οἱ πέντε τρόποι), which are given by Sextus Empiricus as a summary of the later scepticism, are ascribed by Diogenes Laertius (9.88) to Agrippa.
I. The first of these argues from the uncertainty of the rules of common life, and of the opinions of philosophers.
II. The second from the " rejectio ad infinitum :" all proof requires some further proof, and so on to infinity.
III. All things are changed as their relations become changed, or, as we look upon them in different points of view.
IV. The truth asserted is merely an hypothesis or, V. involves a vicious circle. (Sextus Empiricus, Pyrrhon. Hypot. 1.15.)
With reference to these πέντε τρόποι it need only be remarked, that the first and third are a short summary of the ten original grounds of doubt which were the basis of the earlier scepticism. [PYRRHON.] The three additional ones shew a progress in the sceptical system, and a transition from the common objections derived from the fallilility of sense and opinion, to more abstract and metaphysical grounds of doubt. They seem to mark a new attempt to systematize the sceptical philosophy and adapt it to the spirit of a later age. (Ritter, Geschichte der Philosophie, 12.4.)[B.J]