Different doctrines of Plato about the soul. Whether all the three souls are immortal, or the rational soul alone.
The difference which I have here noted shows how Plato modified his doctrine to suit the purpose of each dialogue. The tripartite soul would have been found inconvenient in the Phædon, where the argument required that soul and body should be as sharply distinguished as possible. Assuming passion and appetite to be attributes belonging to the soul, as well as reason — Sokrates will not shake them off when he becomes divorced from the body. He believes and expects that the post-existence of the soul will be, as its pre-existence has been, a rational existence — a life of intellectual contemplation and commerce with the eternal Ideas: in this there is no place for passion and appetite, which grow out of its conjunction with the body. The soul here represents Reason and Intellect, in commerce with their correlates, the objective Entia Rationis: the body represents passion and appetite as well as sense, in implication with their correlates, the objects of sensible perception.[23] Such is the doctrine of the Phædon; but Plato is not always consistent with himself on the point. His ancient as well as his modern commentators are not agreed, whether, when he vindicated the immortality of the soul, he meant to speak of the rational soul only, or of the aggregate soul with its three parts as above described. There are passages which countenance both suppositions.[24] Plato seems to have leaned sometimes to the one view, sometimes to the other: besides which, the view taken in the Phædon is a third, different from both — viz.: That the two non-rational souls, the passionate and appetitive, are not recognised as existing.
[23] This is the same antithesis as we read in Xenophon, ascribed to Cyrus in his dying address to his sons — ὁ ἄκρατος καὶ καθαρὸς νοῦς — τὸ ἄφρον σῶμα, Cyropæd. viii. 7, 20.
[24] Alkinous, Introduct. c. 25. ὅτι μὲν οὖν αἱ λογικαὶ ψυχαὶ ἀθάνατοι ὑπάρχουσι κατὰ τὸν ἄνδρα τοῦτον, βεβαιώσαιτ’ ἄν τις· εἰ δὲ καὶ αἱ ἄλογοι, τοῦτο τῶν ἀμφισβητουμένων ὑπάρχει. Galen considers Plato as affirming that the two inferior souls are mortal — Περὶ τῶν τῆς ψυχῆς ἠθῶν, T. iv. p. 773, Kühn.
This subject is handled in an instructive Dissertation of K. F. Hermann — De Partibus Animæ Immortalibus secundum Platonem — delivered at Göttingen in the winter Session, 1850-1851. He inclines to the belief that Plato intended to represent only the rational soul as immortal, and the other two souls as mortal (p. 9). But the passages which he produces are quite sufficient to show, that Plato sometimes held one language, sometimes the other; and that Galen, who wrote an express treatise (now lost) to prove that Plato was inconsistent with himself in respect to the soul, might have produced good reasons for his opinion. The “inconstantia Platonis” (Cicero, Nat. Deor. i. 12) must be admitted here as on other matters. We must take the different arguments and doctrines of Plato as we find them in their respective places. Hermann (p. 4) says about the commentators — “De irrationali animâ, alii ancipites hæserunt, alii claris verbis mortalem prædicarunt: quumque Neoplatonicæ sectæ principes, Numenius et Plotinus, non modo brutorum, sed ne plantarum quidem, animas immortalitate privare ausi sunt, — mox insequentes in alia omnia digressi aut plane perire irrationales partes affirmarunt, aut mediâ quâdam viâ ingressi, quamvis corporum fato exemptis, mortalitatem tamen et ipsi tribuerunt.” It appears that the divergence of opinion on this subject began as early as Xenokrates and Speusippus — see Olympiodorus, Scholia in Phædonem, § 175. The large construction adopted by Numenius and Plotinus is completely borne out by a passage in the Phædon, p. 70 E.
I must here remark that Hermann does not note the full extent of discrepancy between the Phædon and Plato’s other dialogues, consisting in this — That in the Phædon, Plato suppresses all mention of the two non-rational souls, the passionate and appetitive: insomuch that if we had only the Phædon remaining, we should not have known that he had ever affirmed the triple partition of the soul, or the co-existence of the three souls.
I transcribe an interesting passage from M. Degérando, respecting the belief in different varieties of soul, and partial immortality.
Degérando — Histoire Comparée des Systèmes de Philosophie, vol. i. p. 213.
“Les habitans du Thibet, du Gröenland, du nord de l’Amérique admettent deux âmes: les Caräibes en admettent trois, dont une, disent-ils, celle qui habite dans la tête, remonte seule au pays des âmes. Les habitans du Gröenland croient d’ailleurs les âmes des hommes semblables au principe de la vie des animaux: ils supposent que les divers individus peuvent changer d’âmes entre eux pendant la vie, et qu’après la vie ces âmes exécutent de grands voyages, avec toutes sortes de fatigues et de périls. Les peuples du Canada se représentent les âmes sous la forme d’ombres errantes: les Patagons, les habitans du Sud de l’Asie, croient entendre leurs voix dans l’écho: et les anciens Romains eux-mêmes n’étaient pas étrangers à cette opinion. Les Négres s’imaginent que la destinée de l’âme après la vie est encore liée à celle du corps, et fondent sur cette idée une foule de pratiques.”
The life and character of a philosopher is a constant struggle to emancipate his soul from his body. Death alone enables him to do this completely.