A History of Western Philosophy: And Its Connection with Political and Social Circumstances from the Earliest Times to the Present Day

by Bertrand Russell

The atomists, unlike Socrates, Plato, and Aristotle, sought to explain the world without introducing the notion of purpose or final cause. The “final cause” of an occurrence is an event in the future for the sake of which the occurrence takes place. In human affairs, this conception is applicable. Why does the baker make bread? Because people will be hungry. Why are railways built? Because people will wish to travel. In such cases, things are explained by the purpose they serve. When we ask “why?” concerning an event, we may mean either of two things. We may mean: “What purpose did this event serve?” or we may mean: “What earlier circumstances caused this event? ” The answer to the former question is a teleological explanation, or an explanation by final causes; the answer to the latter question is a mechanistic explanation. I do not see how it could have been known in advance which of these two questions science ought to ask, or whether it ought to ask both. But experience has shown that the mechanistic question leads to scientific knowledge, while the teleological question does not. The atomists asked the mechanistic question, and gave a mechanistic answer. Their successors, until the Renaissance, were more interested in the teleological question, and thus led science up a blind alley.