What does “natural science” look like in Aristotle? The past two weeks we have been reading his Physics, in which Aristotle addresses the science, meaning “knowledge,” of nature. He introduces the subject by describing his method thus: “to start from things which are more knowable and obvious to us and proceed towards those which are clearer and knowable by nature” (184a15). This statement might seem a bit ambiguous, but I think that he means that certain logical principles are more obvious to our minds than all the complexities of the physical world, and that we need to start with the former in order to understand the latter. A few lines down he says, “Thus we must advance from generalities to particulars; for it is a whole that is best known to sense-perception, and a generality is a kind of whole, comprehending many things within it, like parts.” He compares this to a little child who starts by calling all men “father” and then eventually learns to distinguish them. Our baby Joseph is exactly in this stage of pointing to men, whether in the world or in photos, and calling them all “Dada.” He learns what men are through his dad, generalizing outwards from him, but soon enough he will start distinguishing them.
What would this look like in science though? I’ll take as an example one of the topics that he covers—that of motion. Motion, which he uses to stand for “change” in general, is a central principle that Aristotle needs to define, for we see motion and change all around us. In fact, it seems to be a constant in the universe. Aristotle does not pursue what motion is by observing examples in the natural world; he does not measure anything, he does not conduct experiments. Instead, he looks to language, how we talk about things being movable or changeable, or the mover and the moved. If he uses examples, they are as mostly as analogies to understand his logical conclusions. He arrives fairly quickly at this definition of motion: “the fulfillment of what exists potentially, or in so far as it exists potentially, is motion—namely, of what is alterable qua alterable, alteration” (201a10).
Now I’ll try to explain how I understand that! According to Aristotle, things contain potentiality, what they could be, and actuality, what they are now. When we say that a thing is “buildable”—an example that he gives—we mean that it has the potential to be built. When it is being built, that potential is being fulfilled. Motion is that active process of fulfilling what is in potency. Once the process is over, motion or change is no longer occurring.
Aristotle then goes on to defend this definition against counterarguments, and he teases out the implications of the definition for other aspects of his theory. In a very similar way, he also treats time, the infinite, and causation, ending the book with arguments for an “unmoved mover” that is the source of all motion in the universe. The unmoved mover is also the culmination of his Metaphysics, which treats questions beyond the physical world…so why does he feel compelled to bring the metaphysical into his Physics?
After we finished Aristotle, we leapt over a thousand years or so to read the English Renaissance philosopher Francis Bacon, most often cited as the father of the modern scientific method. In his New Organon (published in 1620), he expresses extreme distaste for Aristotle’s approach to natural science that I have just described. Bacon blames Aristotle’s method and its subsequent influence from classical times on through the Middle Ages (via Thomas Aquinas) for the lack of progress he sees in the natural sciences. Bacon thinks man ought to have authority over nature, and man can only do that by attaining better knowledge of how nature actually works.
He writes The New Organon in the form of aphorisms, which are separate and distinct statements of a principle or observation. For example, here is #11 of Book I: “As the sciences which we now have do not help us in finding out new works, so neither does the logic which we now have help us in finding out new sciences.” In #63, he specifically accuses Aristotle of corrupting “natural philosophy by his logic”: “for he had come to his conclusions before; he did not consult experience, as he should have done, for the purpose of framing his decisions and axioms, but having first determined the question according to his will, he then resorts to experience, and bending her into conformity with his placets, leads her about like a captive in a procession.”
Bacon says that one must reject the approaches of philosophy of the past and start anew, with untried methods, to really make progress in the sciences. One must start with the particulars, and dwell among them for a long time, before generalizing to any principles. Whereas Aristotle presumes the strength and truth of of the human intellect as a first principle, Bacon takes the weakness and error of the human mind and senses as a first presumption, and wants to find tools and methods that help to overcome those. And, he firmly asserts that there should be no talk of final causes or creators or metaphysical questions at all.
I have to admit that the Scientific Revolution ushered in by men like Bacon does seem attributable to this shift in method and focus—he describes a new philosophical paradigm for science which is so close to our modern sensibilities. But is it because of a drastic “revolution” from the past? Is Bacon as distinct and separate from tradition as he seems to think? Are the two methods so irreconcilable, or was the later approach actually a natural outgrowth from slow developments of the ancient one? Can the one inform the other?
Our good friends from Portugal, Leanor and Nuno, trusty readers of this blog, are soon to move to Baltimore. Nuno studies the History of Science and so I entreat him to prepare to discuss these things with me, and I will report back on our conversations if they illuminate any of these questions I have!