Later he calls the soul the cause (aitia, ‘the reason for’) or first principle of the living
body, its final cause. We believe that we possess scientific knowledge of a thing when
wethink we know its cause. We must acquire knowledge of original causes, of which
there are four: the material, the formal, the efficient (what makes something come to
be) and the final (the end which it serves, from finis, the Latin word translating telos,
whence teleological, and meaning ‘end’). If we take the example of a house, the
material cause tells us about the material of which it is constructed; the formal cause
tells us of the structure or the plan of the house; the efficient cause tells us what is
necessary for the building of the house, such as the art of building and design; the final
cause tells us about the function of the house (see e.g. Physics,2, 3, 24). These famous
Aristotelian distinctions represent a new clarity and definition in relation to previous
thought about causation.
The four causes apply equally to natural things.
Hence, if it is by nature and also for a purpose that the swallow makes her nest and
the spider his web, and that plants make leaves for the sake of the fruit and strike
down (and not up) with their roots in order to get nourishment, it is clear that
causality of the kind we have described is at work in things that come about or
exist in the course of Nature.
(Physics, 2, 8, 25)Nature is a ‘principle of movement and change’. The movement is always the
realisation of an end, the actualisation of an original potentiality. Aristotle’s thought
is therefore thoroughly teleological. As there is a final so there is a first cause. ‘So
inasmuch as motion [kinesis]is eternal, it follows that the prime mover, if it be single,
or the prime movers, if plural, must likewise be eternal’ (Physics, 8, 6, 8). The Unmoved
Mover exists in a state of eternal contemplation.
What then is the final cause of man? What is his purpose or his end? What is
peculiar to man is that which distinguishes him from the vegetable and animal worlds,
his rational faculty enabling rational activity:
Let us take it that what we are concerned with here is the reasoning power in
action for it is generally allowed that when we speak of ‘reasoning’ we really
mean exercisingour reasoning faculties. ... The function of a man is the
exercise of his non-corporeal faculties or ‘soul’ in accordance with, or at least not
divorced from, a rational principle. ... The good for man is ‘an activity of soul in
accordance with goodness’ or (on the supposition that there may be more than
one form of goodness) ‘in accordance with the best and most complete form of
goodness.’
(Ethics, 1, 7)206 THE GREEKS