Journal of the History of Philosophy

Judgment and Perception in Theaetetus 184-186 JOSEPH SHEA THEAETETU8 184b-186e is intended to show that perception cannot be knowledge (186e9-12). The argument to this conclusion is straight-forward: (1) One cannot attain truth if one does not attain being (186c7). (2) One cannot have knowledge of that the truth of which one has not attained (186c9-1 o). (3) Perception cannot grasp being nor [by (1)] truth (186d3- 5 186e4-5). Therefore, (4) "Knowledge is something other than perception" (186e12). The first two premisses are unexceptionable. The third turns on the fact that being is a • (common object), one of the things which Theaetetus (correctly) says "the mind itself ~uSt [by means of] itself" considers (185el). Perception cannot grasp being because being is not the proper object of any particular faculty? Being is not got at by any one "instrument" save the mind itself (x85c5-9), unlike color, sound, et al., each of which is reached by the mind 6t6 some instrument, e.g., ears. One can hear two sounds 6t6 the ears, but it is not the faculty of hearing which allows one to say that the two sounds are the same or different. The third premiss, then, also seems plausible , a simple consequence of the argument at 184c-185d against the possibility of grasping a • through a faculty of perception. Since perception cannot get at being, it cannot be knowledge, for knowledge requires (at least) a judgment of the form "x is F," and perception ~ again, cannot get at the "being" such a judgment requires. Some recent commentators2 have been puzzled as to what perception without any sort of See 184e8-185a2 for the proper objectdoctrine. I willconcentrateonJohn Cooper,"Platoon Sense-Perceptionand Knowledge:Theaetetus 184--186,"Phronesis 15 (197o)and D. K. Modrak,"Perceptionand Judgment in the Theaetetu~," Phronesis 26 (1981). [1] 2 JOURNAL OF THE HISTORY OF PHILOSOPHY 23:1 JANUARY 1985 judgment could be, and have interpreted Plato as a phenomenalist. This allows them to say that in perceiving certain trivial, uncorrectable judgments are made, which judgments differ in kind from those involved in knowledge . A different sense of "truth" is then attached to each sort of judgment as a way of explaining what Plato meant by saying that perception cannot get at truth. Thus, in attributing phenomenalism to Plato these commentators save appearances for him: perception does not involve judgment in a fullblooded sense, but only in a weak one which involves a correspondingly weak sense of truth. Plato is understood as asserting that "perception cannot get at truth in the strong sense of truth." By attributing phenomenalism and the distinction between a weak and strong sense of truth to Plato, these commentators find in Theaetetus 184-186 a notion of perception they find intelligible (i.e., one that has perception involve some sort of judgment), while still acknowledging Plato's claim that perception cannot get at truth. This phenomenalist interpretation seems to me far off the mark. Some of the claims essential to this reading are unsupported by the text, and in its general force this reading conflicts with Plato's other goal in the passage, viz., to establish that perception and judgment are accomplished by one mind. I believe that in demonstrating that perception cannot be knowledge, Plato also succeeds in improving his own earlier account of perception in the Republic, according to which the sense organs, rather than the mind, perceive . This allows me to make good sense of Plato's emphasis on the dative vs. ~ construction, i.e., on the distinction between perceiving with an organ and perceiving by means of an organ, and to relate the distinction to the other main theme of the section: perception cannot get at truth because it cannot make any judgment, for only the mind "by itself" (• ~6~v), i.e., the mind precisely when it is not using the sense organs as its instruments, can judge. Before expanding and defending these views, however, I consider in detail two phenomenalist readings, both to show why they fail and to trace the misconception that led their authors to them. As do most commentators since Cornford, I ignore that broad interpretation which finds in...