Two Meanings of Why
In ancient science, which drew analogies between the behavior of living entities and that of nature, there was the general belief that things happen with a purpose. We water the flower bed so that flowers may bloom. Likewise, it was argued, it rains so that there would be harvest. In Aristotelian science, an explanation was never complete until a final cause (purpose) was detected. As David Lindberg summarized it: “The world of Aristotle is not the inert mechanistic world of the atomists, in which the individual atom pursues its own course mindless of all others. Aristotle’s world is not a world of chance and coincidence, but an orderly organized world, a world of purpose, in which things develop towards ends determined by their natures.” Other ancients, like Galen, also held the view that nothing happens in nature without some purpose.
Suppose that we ask students enrolled in a course why they are taking it. Consider the two following answers to this question: (a) Because it is a required course, and I need three more credits to graduate, etc. (b) Because I want to learn something about this subject, and I want to become a philosopher of science.
We note that the first answer refers to a built-in system that was established in the past and in which the event occurs. That is to say, one can understand why the student took the course in terms of a set of rules to which she was subjected. On the other hand, the second answer refers to something that expresses a purpose, to something that is yet to happen. Here the explanation involves a goal. The first type is a mechanistic explanation since it explains in terms of how a machine would function. However, in this context, the term does not quite mean that one views the world simply as a machine, but that one tries to explain it in terms of well defined laws of nature. A first systematic formulation of what came to be known as the mechanistic philosophy was by René Descartes. Michael Sean Mahoney pointed out that Descartes’ work “captured the thrust of contemporary creative thought and showed where it could lead. What had previously been a set of isolated experiments in mechanical explanation became the constituents of a unified program of natural philosophy.” As to what prompted Descartes to propose the mechanical model, it has been suggested that “the universe had begun to seem (to Descartes) self-evidently mechanical as he reflected on sophisticated machinery (clocks, looms, pumps, and fountains) of sufficient ingenuity to match some of nature’s more recondite operations.”
One of the key points of divergence between science and religion is precisely on the question of whether there is a universal purpose or not. Science, especially physics, tries to offer mechanistic explanations for natural phenomena: i.e. science tries to explain the world in terms of causally connected series. In the religious framework, on the other hand, there is a purpose to the universe at large, if not to every single event in it.
The founders of modern science, like Galileo Galilei, Francis Bacon, René Descartes, and Isaac Newton adopted the mechanical model for explaining natural phenomena. They held the view that the world consists of material units which undergo changes and motion when external forces act on them, in accordance with well-defined laws. These effects can be studied experimentally and analyzed mathematically. Such a notion has implications on our overall worldview regarding God and spirit, and so it was not universally or unconditionally adopted. Yet, practically all the initiators of the mechanistic philosophy were religious and God-fearing men, suggesting that the compatibility of science and religion is more a matter of subjective responses than objective criteria.
It is also a fact that for more than two centuries, those who explored the physical world in this framework were extraordinarily successful in their efforts to understand and explain a very wide range of phenomena. And they could also predict many phenomena on the basis of the mechanical model.