As is so often the case with questions of this sort, a lot depends on what is meant by the terms.
If the term evolution includes the strange ethics, suspect metaphysics and optimistic ideas about progress that some try to extract from science — in other words, a raft of extra–scientific accretions — then evolution is not a theory in the scientific sense.
Social Darwinism, for instance, is an amalgamation of science and a whole lot of bad ethics; the public have a right to be concerned when such wolves come to them in sheep’s clothing. It is a welcome service to science that philosophers such as Mary Midgley have exposed dubious religious claims masquerading as evolution.
However, by evolution I mean -biological evolution, the scientific theory of the naturally occurring diversification of life. Yes, naturally.
It is odd that some Christians object so fiercely to naturalism in evolution when that central event of the Christian faith, the death of Christ, happened quite naturally rather than supernaturally. Indeed, it has to be so otherwise God is culpable for the death of his Son. This suggests that theological reflection might be a useful antidote to this anti-evolutionism, and why it is that evolution does not bother theologians.
What is a theory and what is a fact?
On the street, theories are held to be -little better than airy-fairy conjectures, whereas statements of fact are held to be true. But — and this is key in coming to understand the ”evolution is a fact … evolution is a theory” issue — theories are not necessarily less certain than facts as is popularly thought. Facts are confirmed observations, not truth.
Facts do one job, theories quite another. Theories explain facts. They are models or maps or abstractions that make sense of data. Alfred North Whitehead pointed out that the genius of science is its twin concern with the particular (the facts) and the general (theory). If science were merely concerned with statements of fact then reality would be the best model of itself. Such a model would be useless to humans and biology would be ”merely stamp-collecting”, as Lord Rutherford famously claimed.
A good theory, one that unifies and explains a great many facts, is a very good thing.
Biological evolution is so general a phenomenon that it is impossible to do it justice in a few words. The theory joins such fields as genetics, biochemistry, cell biology, developmental biology, comparative anatomy, the fossil record, biogeography and ecology, and intersects with a great many others such as plate tectonics, geology and cosmology. It takes a great deal of intellectual effort properly to assess the theory. Yet there is no shortage of people outside these fields who think they are up to it. I Googled ”evolution is only a theory” and received 41 900 hits whereas ”big bang is only a theory” received only 182 hits. I admit to being a bit peeved. Why should evolution get such stick when both are natural?
Perhaps because most people feel much more familiar with butterflies and flowers — the stuff that evolution seems to be about. However, philosopher of science Mary B Williams made an important point when she said that much of the significant evidence for evolution is not human-sized.
The predictions made by evolution are about patterns in sets of phenomena, rather than individual events. We cannot easily point to this evidence because we do not have enough fingers and we do not live long enough. The data are rich and global in extent and deep in time.
Humans are biased towards individual events. The Doberman Pincher, especially when it is chasing me, seems more concrete, more real than bio-geographical evidence. However, it is the latter that provides such compelling support for evolution and which is so largely ignored in anti-evolutionary writing.
Williams’s point applies no less to the fossil record. Evolutionary theory does not hang upon some individual fossil. It is the patterns in the fossil record that are so telling. And it is this that creates a problem when trying to tell the evolutionary story to a non-specialist.
Only a smattering of the evidence has been touched on here but perhaps enough to begin to show why palaeontologists and neontologists are so happy with the theory. Evolution is not ”just a theory”. It is an extremely good one. Now that’s a fact.
Dr Mike Anderson is qualified as an evolutionary scientist and philosopher
A matter of great importance
Is evolution a theory? Yes it is. It makes the grand claim that all living things on Earth are related through common descent.
Is it a fact?
Not in the same sense as ”my pet crow is black”. Evolution is far too important to be a fact in this sense. It is a fact in that the theory explains a huge body of data and no evidence has yet been found to refute it. This fact remains even though there is dispute over the relative importance of the mechanisms behind evolutionary change. This dispute can be exaggerated. Almost all biologists agree that natural selection acting upon inheritable variation is very important.
It’s a fact
Excerpt from the introduction by Stephen Jay Gould to Evolution (2002), by Carl Zimmer: ”In discussing the truth of evolution, we should make a distinction, as Darwin explicitly did, between the simple fact of evolution — defined as the genealogical connection between all earthly organisms, based on their descent from a common ancestor, and the history of any lineage as a process of descent with modification — and theories [like Darwinian natural selection] that have been proposed to explain the causes of evolutionary change.”
Excerpt from The Intellectual (2005), by Steve Fuller, professor of sociology at the University of Warwick: ”I [defended] the school district’s decision to tell students, aged 15, that Darwin’s theory of evolution is ultimately just a theory, and that another theory — that of ‘intelligent design’ — might be used to account for the nature of life.”