[2] Hyp. I. 94.
[3] Diog. IX. 11 81.
[4] Hyp. I. 99.
The non-homogeneous nature of the mental images connected with the different sense organs, as presented by Sextus, reminds us of the discussion of the same subject by Berkeley in his Theory of Vision.
Sextus says that a man born with less than the usual number of senses, would form altogether different ideas of the external world than those who have the usual number, and as our ideas of objects depend on our mental images, a greater number of sense organs would give us still different ideas of outward reality.[1] The strong argument of the Stoics against such reasoning as this, was their doctrine of pre-established harmony between nature and the soul, so that when a representation is produced in us of a real object, a καταληπτικὴ φαντασία,[2] by this representation the soul grasps a real existence. There is a λόγος in us which is of the same kind, σύγγενος, or in relation to all nature. This argument of pre-established harmony between the faculties of the soul and the objects of nature, is the one that has been used in all ages to combat philosophical teaching that denies that we apprehend the external world as it is. It was used against Kant by his opponents, who thought in this way to refute his teachings.[3] The Sceptics could not, of course, accept a theory of nature that included the soul and the external world in one harmonious whole, but Sextus in his discussion of the third Trope does not refute this argument as fully as he does later in his work against logic.[4] He simply states here that philosophers themselves cannot agree as to what nature is, and furthermore, that a philosopher himself is a part of the discord, and to be judged, rather than being capable of judging, and that no conclusion can be reached by those who are themselves an element of the uncertainty.[5]
[1] Hyp. I. 96-97.
[2] Adv. Math. VII. 93.
[3] Ueberweg Op. cit. 195.
[4] Adv. Math. VII. 354.
[5] Hyp. I. 98-99.