Word Count: 1,667.

The thesis of this brief and exceedingly elegant book is that Plato,
certainly in the late dialogues and probably also in the middle period
ones, regarded nous as God and as the ultimate cause
of order in the universe. One should not expect to find the doctrine expounded
in the middle dialogues, Menn claims, because there Plato's interest is
focussed on the intelligible world and how the human intellect can attain
to a grasp of it. But in the later dialogues, where his concern evidently
turns to accounting for the sensible together with the intelligible world,
he needs to introduce nous as the cause of order in
the sensible world. The reason for this is that Forms can account only
for what it is for each thing to have the features it has: they can no
more account for why a thing has the features it has at a certain time,
or why it is related to other things that have other features, so that
the totality is harmonious and intelligible, than can the mere postulation
of a material cause. However, nous, understood as an
active causal principle which aims at what is best, does account for these
things. An appeal to the Forms, then, gives only a 'second-best' explanation
of change in the sensible world; the first-best explanation invokes nous
(cp. Phaedo 97c-99c).

Plato's doctrine of nous, according to Menn, is this:
(i) nous is best understood, not as Mind, but rather
as Reason, "a single substantial unity ... distinct from the world-soul
and from all other souls, superior to souls ..." (7); (ii) it is
correctly
identified with the demiurge of the Timaeus; in fact,
the term 'demiurge' signifies merely a relation or role, whereas nous
is the very name of this maker; (iii) although nous
exists independent of bodies and can act directly upon bodies in the manner
of an efficient cause, it prefers to act through 'persuasion' rather than
'coercion' (Timaeus 48a2-5), thus it needs some sort
of mediation for its action; and (iv) this mediation is provided by soul,
a principle of self-movement, which can participate in nous
and have its effects ordered by nous.

Menn maintains (i) against passages of Plato that assert that nous
cannot come to be apart from soul (e.g. Phileb. 30a9-10,
Euthyd. 287d7-e1, Soph. 239a4-8,
Tim. 37a2-4, 46d5-6) by pointing out that Plato should
be taken to mean, exactly, that it cannot come-to-be,
that is, come to exist and act in the sensible world, without soul, which
of course does not imply that it cannot exist in the intelligible world
on its own; and Menn accepts R. Hackforth's arguments1 that, in places
where Plato seems to deny that nous exists independent
of soul, he is speaking, not of nous as creator, but
as something in the world, which the world contains by means of soul.

To defend (ii), Menn must of course argue against a view such as F.
Cornford's, that the demiurge is simply "the Reason in the
World-Soul".2 He does so by pointing out
that the World-Soul but not the demiurge is
in the class of the gignomena, and that the demiurge
imposes limits on the unlimited, which is the action from which soul, too,
results. He must likewise, of course, reject H. Cherniss' view that nous
is "a personification of the logical abstraction, 'intelligent causation'
in general".3 As against this, Menn
argues persuasively that otherwise
uncoordinated, intelligent causes could not in fact produce an ordered
universe, and so the world's order would remain unexplained, if Plato believed
what Cherniss attributes to him. Furthermore, we would have to conclude
that Plato in fact had no opinion about the first cause of the world, since
he simply postulates a plurality of intelligent causes, which could not
be taken to be primitive or original. (Menn seems to assume, though he
does not argue, that Cornford and Cherniss together cover the more plausible
alternatives to his interpretation.)

One of Menn's key arguments for the independence of nous
from soul is the consideration that, as he puts it, "the nous
that is king of heaven and earth is the virtue of
nous" (16).
That is to say: when Plato lists nous along with phronesis
and episteme as virtues of the souls of particular human
beings, as he does in many texts (e.g., Phileb. 13e4,
21d9-10, 28d8; Tim. 34a2; Laws 963a6-9),
he is referring to the same thing as that to which he refers, when he calls
nous king of the universe. The argument for independence
then apparently proceeds: since souls can exist without having the virtues,
they can in particular exist without nous; and if nous
is like the other virtues, and indeed like other universal terms, then
it must have a status for Plato like other universals and exist prior to
particulars.

Other support for the idea that Plato regards nous
as independent of soul comes from Menn's fascinating discussion of Plato's
puzzling claim that his own doctrine of nous is simply
what has been held previously by "all the wise" and "those
who were before us" (cf. Phileb. 29c6-8). Note
that even if we were to grant Socrates pre-eminent authority as a predecessor
of Plato, and if we were to accept Memorabilia I.iv.8
as a reflection of the historical Socrates' views, Plato's assertion would
still be puzzling. Only Anaxagoras among the pre-Socratics, it seems, mentions
nous; and the method of explanation through material
cause, common among the early natural philosophers, seems to indicate,
precisely, a failure on their part to acknowledge the importance of providing
a cause of the order of things, which is the function
served by Platonic nous.

Menn would explain Plato's assertion in two stages. He argues, first
of all and plausibly, that Plato's doctrine of nous
is a development of Anaxagoras' teaching, in the sense that it responds
to tensions and difficulties in the latter. Anaxagoras regarded nous
as similar to what was indicated by other mass nouns ("water",
"earth", etc.). But then it becomes a problem how nous,
as distributed among different particular substances, nonetheless acts
in a coordinated way, so that the entire world becomes a single ordered
whole. Menn sees Anaxagoras' insistence that nous alone
is 'unmixed' as an attempt to respond to this problem; but Plato's hypothesis
of an independent, controlling demiurge clearly handles the problem better.
Again, the manner of action of Anaxagorean nous
is difficult to account for. How does nous, as present
for instance in a particular human being, bring about order and rationality
in that person's actions? Anaxagoras has only one view open to him: nous
acts directly upon the body, in the manner of an efficient cause, and by
'coercion' rather than 'persuasion'. (That Anaxagoras was constrained to
adopt this view explains, Menn thinks, why Aristotle held that Anaxagoras
tended to identify nous and soul: if soul is what is
responsible for motion in things, then nous is soul.)
But Plato proposes, instead, the view that nous needs
something in which to act, viz. a principle of self-movement, or soul,
in which case it acts through lending rationality to self-motion, that
is, by 'persuasion'.

But once we accept that Plato saw his doctrine of nous
as a development of a prominent pre-Socratic view, then we can appreciate
that he would wish to assign his view, in a general way, to his forebears.
The important consideration here is not that other pre-Socratics used the
term 'nous', since they did not. Menn maintains, rather,
that we should look to the tendency of the early natural philosophers to
identify what they took to be the basic ordering principle of the universe
with a virtue or with something virtue-like: for instance, it is Dike
and Logos for Heracleitus; Dike similarly
for Parmenides; and Philia in Empedocles (on this last
point, Menn would have us compare Plato, Gorg. 507e6-508a2).
Thus, by insisting that "the nous that is king
of heaven and earth is the virtue of nous",
Menn can account nicely for Plato's understanding of the provenance of
his own cosmological view: Plato was simply continuing the idea the governance
of the universe takes place through the action of virtue; but for him the
virtue, nous", was also something separate and
self-subsistent.

Menn's monograph is a coherent, compact argument, prosecuted in carefully-argued
stages, and supported with impressive scholarship in detailed footnotes.
He regards this brief book as a necessary prolegomenon to a longer study
of Aristotle's Metaphysics, since Menn thinks that that
treatise takes the cosmology of the Timeaus as its starting
point. We should expect a great gain in insight into that difficult work
of Aristotle, if Menn's promised investigation of it is as subtly argued
as this, and in the same way based on illuminating philology and exegesis.