The concept of final cause brings us close to the biological source of Aristotle’s thinking.
His expression “that for the sake of which” corresponds closely to the biological concept
of function.
Aristotelian “that for the sake of which” is not, in itself, a concept of purpose.
Aristotle makes this quite clear in the Nicomachean Ethics, where he tells us that purposive action
is action that involves deliberate choice.
But Nature does not deliberate.
The ends of Nature are forms internal to the natural entitites whose forms they are.
(At places Aristotle does use expressions suggesting a less sophisticated teleology
of deliberate purpose, such as “Nature does nothing in vain.”
But we should attend to his explicit analysis of the meaning of “nature” and “final
cause” for his true view.)
Things, the things we meet in the world, oak trees and octopuses, are knowable because
as such things, things of definite kinds, they contain in themselves determinate principles
which make them the things they are and make them undergo the transformations they undergo.
Nobody, no Jehovah or Zeus, decides to turn a tadpole into a frog.
But to be a tadpole is to be the offspring of a frog, enagaged in the ongoing process
of becoming an adult frog, according to the ontogenic pattern that is “frog.”
There is no capital-N Nature, but each kind of being has its nature, which bounds its
material aspect and orders its changing states towards the achievement of its appropriate final form.
Aristotle’s conceptions of being, of knowledge, and of man all depend on the recognition of
such inherent principles in natural kinds of things.
Aristotle’s achievements in biology would be inconceivable without this fundamental
recognition, drawn from observation, of the forms and functions characteristic of living organisms.
Some accounts of Aristotle’s biology hold that his genuine achievements, in particular
his detailed knowledge of chick embryology, are compromised by his unfortunate lapses
into a psychologizing or anthropomorphizing teleology.
But this misunderstands altogether the character of his enterprise both as a philosopher and
as a biologist.
For it is precisely his grasp of the operational principles of organisms, of the coincidence
of form and function, that makes him at once the philosopher and the biologist that he is.
As William Ritter wrote in 1932: “The teleology for which Aristotle is roundly condemned by
many present-day biologists he was not at all or very slightly guilty of.
On the other hand those who condemn the teleology which he did hold, that of completed wholeness
as essential to the adequate interpretation of any phenomena of nature whatever, are in
so far not only failing, themselves, in reaching such interpretation, but are tacitly denying
the possibility of it.”
In short, it is the control of every step in a natural process by the character of the
whole which serves as Aristotle’s model for the “final cause.”
To repeat: the character of the whole being controls every step of its development, and
this is what it means to speak of its “final cause.”
Purposive human action is a limited case of such forward-directedness, with the added
qualification of the knowledge and deliberate choice that humans bring to their human activities.
Aristotle is primarily interested in the intrinsic directedness of organic development, which
is not itself thinking or planned by thought, but which, like thought, is ordered and determinate.
It is therefore an appropriate object for thoughtful examination by the philosopher-biologist.
Aristotle finds his model of intelligibility in the observed finite and recurrent life-histories
of animals and plants, and in the structures which develop in those life-histories.
Without these form-in-individuals, no single item of knowledge can be knowledge at all.
To detach efficient from final, or material from formal causes, as modern biologists profess
to do, would be, for Aristotle, to throw the intelligible back into the unintelligible,
to turn from the principles of things to their mere conditions.
It would be to turn knowledge into the vain search for knowledge, to make of man a useless
passion, as some modern thinkers do and perhaps must do, but as Aristotle decidedly does not.
We do have knowledge, Aristotle believes, not because we can take the development of
a chicken to bits as if it were an artifact, not because we can recontruct the whole out
of its parts.
We have knowledge because there are wholes, that is, finite structures, developing as
individuals, but eternal as species, which it is within the power of our finitude, our
specific form as human animals capable of memory, experience, insight and rational discourse,
to discover by induction and to elaborate in scientific argument.
Without the directedness of nature there would be nothing, no things, for us to know.
And this directedness includes the directedness of our own existence, in which pure knowledge
for its own sake is the highest and most fitting goal.
This is not a teleology which takes some astute “scientific” observations and predictions
then adds to them some superstitious and ignorant remarks about nature’s purposes.
It is teleological science, that is functional science, the study of the rhythms of change
characteristic of living things.
These rhythms cannot be understood, any more than musical rhythms can be, as aggregates
of isolated bits.
They are intelligible only as the whole patterns that they are.
And in temporal patterns it is the outcome – the frog or the man, the rose-tree or
the thistle – that governs the pattern leading to it.
The essential time scheme of Aristotelian nature is not predicition from the present
to the future.
It is prediction from the future to the present.
As Aristotle writes in Parts of Animals: “Thus matter and genesis must be first in
time, but logically the substance and form of each thing is first.”