Previous posts review Matthew Stanley’s book, which describes how theistic science was displaced by naturalistic science in 19th century Britain. He calls the latter “scientific naturalism,” which is accurate since it is a version of the philosophy, naturalism. It would be opposed by “scientific theism,” though I don’t think he uses that term, perhaps because he didn’t want it to be confused with a particular version, such as the Scientific Theism of Augustus Hopkins Strong (of Strong’s Concordance fame).
One theme of Stanley’s book is the meaning of the uniformity of nature to theists and naturalists. However, he does not say that this was a new principle, one that was not previously thought necessary.
As John P. McCaskey points out in Induction Without the Uniformity Principle, the principle of uniformity goes back to Richard Whately and J. S. Mill and is based on their view of induction, which has this form:
This is true of some.
What is true of some is true of all.
Therefore, this is true of all.
The second statement (the major premise) is a uniformity principle. J. S. Mill made this central to induction. In 1843 he wrote:
Every induction is a syllogism with the major premise suppressed; or (as I prefer expressing it) every induction may be thrown into the form of a syllogism, by supplying a major premise. If this be actually done, the principle which we are now considering, that of the uniformity of the course of nature, will appear as the ultimate major premise of all inductions.
But in fact induction does not require a uniformity principle. McCaskey points out:
The other, and older, way to think about induction—Aristotle’s way, later revived during the Scientific Revolution—was to think not of particular and universal statements but of particular things, kinds of things, and universal properties, especially defining properties. If, say, attracting iron is a defining property of magnets, then by definition all magnets attract iron. In this way of thinking, the hard part is to figure out what properties should qualify as necessary to the class.
McCaskey’s whole article is worth reading but let me quote two more paragraphs:
The whole project of mature abstract thought is to identify similarities and differences, uniformities and changes, and to classify accordingly. And that—to Aristotle and followers such as Bacon and Whewell—is what induction is.
For them, classification, and therefore induction, comes before uniformity, not the other way around. It’s not that you must presume uniformity in order to classify. It’s that you classify to find uniformities. For Whately, uniformity is primary. For Aristotle’s followers, classification is primary.
These two views of induction encapsulate two kinds of science: (1) a science in which classification and the distinction of types is primary, whereas questions of uniformity or change are secondary; and (2) a science in which uniformity and uniform change are primary, whereas classification and the distinction of types is secondary.
The uniformity view of induction prepared the way for Darwin. An extreme version of the uniformity of nature prepared the way for scientific naturalism.