In biology, when we ask
why an animal has this particular form and structure, why it has these organs and not others, and why they are combined and connected with other organs the way they are, we will not be satisfied, if someone gives us all the
efficient causes that have played a role in the process. When, in reference to the form and structure of living beings, we ask ‘Why?’, what we really want to know is what this particular form and structure is
for – we might as well say: what it is
good for. In Aristotle’s view, the
logos of living organisms, i.e. the real reason why they are what they are, is their
telos. Objective moral truth presupposes that there is teleology in the natural order,
ends toward which things are naturally directed. Teleology is indispensible if we want to make sense of medicine, for medicine is concerned with restoring our bodily processes to the way they should be.