A theory, as the word is used in science, doesn’t mean an unsupported speculation or hypothesis (the popular use of the word). A theory is, instead, a big idea that encompasses other ideas and hypotheses and weaves them into a coherent fabric. It is a mature, interconnected body of statements, based on reasoning and evidence, that explains a wide variety of observations. It is, in one of the definitions offered by the Oxford English Dictionary, “a scheme or system of ideas and statements held as an explanation of account of a group of ideas or phenomena; . . .a statement of what are known to be the general laws of something known or observed.” Thus atomic theory, quantum theory, and plate tectonic theory are not mere speculations or opinions, but strongly supported ideas that explain a great variety of phenomena. There are few theories in biology, and among them evolution is surely the most important.This says that evolution is a theory, but then says that it is a fact instead. But note that he wants to say that a theory must be a "strongly supported idea", even tho his dictionary definition does not say that at all. As a comment says:
So is evolution a fact or a theory? In light of these definitions, evolution is a scientific fact. That is, the descent of all species, with modification from common ancestors is a hypothesis that in the last 150 years or so has been supported by so much evidence, and has so successfully resisted all challenges, that it has become a fact. But this history of evolutionary change is explained by evolutionary theory, the body of statements (about mutaitons, selection, genetic drift, developmental constraints, and so forth) that together account for the various changes that organisms have undergone.
It’s worth emphasising that calling something a theory says absolutely nothing about its truth. Theories range from the theory of conic sections (a branch of geometry, and as certain as anything can be), through Newton’s theory of gravity (true up to a point), and ideal gas theory (true of a non-existent gas, to which real gases approximate), to the Steady State theory of the Universe (wrong).I would add String theory and many-worlds interpretation. These are pure fantasy, as there is no way to determine whether they are true or false.
Today, leftist-atheist-evolutionist Jerry Coyne moves on to complaining that this 1873 Darwin quote is out of context:
“The impossibility of conceiving that this grand and wondrous universe, with our conscious selves, arose through chance, seems to me the chief argument for the existence of God.”The context is that Darwin is not persuaded by the argument. Coyne hates the suggestion that a great scientist might not have been an atheist. But Darwin's point is that evolution directly attacks the chief reason for believing in God, and modern evolutionists like Coyne say the same thing, as noted below. I don't really agree with them, but I do think that this attitude of evolutionists explains why evolution is so controversial.