Thank you, Panchi, for prodding me to get writing! I needed that. But life is so busy these days that I am going to have to write in small portions, which maybe is just as well.
So, first, I would like to make a fundamental, guiding observation about physics and history.
Many philosophers of science have observed how physicists have proceeded historically, and then drawn instant universal conclusions about how physics ought to proceed. For example, Galileo, Descartes and Newton all did physics mathematically, and in certain writings went so far as to suggest that “the book of nature is written in mathematics.” That thinking has largely dominated physics ever since, and so philosophers of science have drawn the conclusion that this must indeed be the character of physical science. Certain philosophers of science have gone further still: anxious to preserve their philosophical domain from the potential intrusions of science, they have maintained that physics and natural philosophy are distinct sciences, one of the principal marks of distinction being this very fact, that physics is a purely quantitative science, whereas philosophy extends beyond the quantitative. This, for example, is the view expressed by James Weisheipl in Nature and Gravitation. More recently, Anthony Rizzi has argued in the same vein (e.g., in his book, The Science Before Science), claiming that physics is a “ratiometric” science, and thus distinct from natural philosophy which is not purely ratiometric.
It is shortsighted, though, to presume that the way physics has proceeded is the way it ought to proceed. It is true that the scope of physics and the scope of philosophy are different, and it is even true that the philosopher, more than the physicist, is the one who is in a position to understand the difference. But for that very reason, natural philosophers ought not to merely presume that how physics has proceeded is the same as how it ought to proceed. Nor should they presume that the apparent distinction and relation between physics and philosophy has been fully revealed and made clear.
It most of all belongs to the natural philosopher to recognize that things have natures, and that there is a fundamental distinction to be made usually between how a thing happens to be, and how it is by nature. And this applies to science as well: one should suspect that there is a natural way of doing physics, and that it may well be different from the way it has been done. History itself surely urges this conclusion upon us; for the way that physics was done before Galileo and Newton was very different from the way it is done now, and the consequences of that change have been momentous. Hence if one had presumed, in, say, the year 1400, that the way physical science was done was the same as the way it ought to be done, one would have been seriously mistaken. It is clear that something needed to change in the way it was done, and something did change. Yet it would still be a mistake to suppose that the change was quite enough; to merely assume that would be to make the same mistake again.
But, one might ask, how will one judge such things by anything besides what we actually observe? Can a philosopher do any better than to respect what the physicists actually do, and accept that as definitive? Would it not in fact be presumptuous of philosophers to make judgments about physics taken from principles external to physics itself?
While this might seem presumptuous, the truth is more complex and interesting. In my next post, I will explore this further.