My previous posts on this topic are here, here, and here. I am indebted to John P. McCaskey’s writings on the subject of induction (see here). In this post I want to make the connection between the principle of the uniformity of nature with naturalism.
In the 18th century there was a decline in understanding induction and an increase in skepticism about it, notably from David Hume and Immanuel Kant. The “problem of induction” in philosophy stems from this time and is often considered insoluble. The simplest solution is to accept as a principle that nature is uniform. J. S. Mill endorsed this solution, which became widely accepted in the 19th century. Today many consider science impossible without it.
The possibility of scientific history arises with a principle of uniformity. Uniformitarianism is “uniformity in time” (James Hutton), which was taken as the foundation of historical geology. Similarly, evolutionism is uniformity in time, taken as the foundation of historical biology. Among other things, that confuses history and science. Genuine induction is synchronic and universal, not focused on the diachronic particulars of history.
Modern inferential induction is less concerned with justification than with quickly finding new discoveries. It takes generalizations with some data behind it (possibly cherry-picked) and applies the uniformity of nature so that future observations will show the same result. But that requires similarity and what counts as similar? That is the key question that real induction answers with evidence-based universal concepts and definitions.
What would geology for example look like with no principle of uniformity? It would mean that geologists defined terms and processes based on observations, then went out looking for things that matched those definitions. The result would not be a pseudo-history of the earth but a real science of the earth that is systematic, consistent, and as complete as geologists can make it. Such a science could be used by historians and archaeologists with their documents and artifacts to develop a history of the earth. That’s how science and history should work together.
Naturalism is the application of uniformity to the whole search for truth. Previous posts tell how it became the dominant philosophy of science in the late 19th century (see here). Naturalism is based on an absolute uniformity of nature. It makes nature an autonomous, all-encompassing substitute for God.
John McCaskey has good news for us. Science doesn’t need naturalism or a principle of uniformity. Evidence and intuitions of uniformity can be embedded into definitions instead. Science can be demonstrably true.