 First, the Creationists argue that at best evolution is only a theory and not a fact, and that theories should never be taken as gospel (if one might be permitted a metaphor). They claim that the very language of evolutionists themselves show that their ideas are on shaky grounds. To which charge evolutionists respond that this is to confuse two senses of the word ‘theory.’ Sometimes we use it to mean a body of scientific laws, as in ‘Einstein’s theory of relativity.’ Sometimes we use it to mean an ‘iffy hypothesis,’ as in ‘I have a theory about Kennedy’s assassination.’ These are two very different senses. There is nothing iffy about the Copernican heliocentric theory. It is true. It is a fact. Evolutionists argue that the same is the case with evolution. When talking about the theory of evolution, one is talking about a body of laws. In particular, if one is following the ideas of Charles Darwin, one is arguing that population pressures lead to a struggle for existence, this then entails a natural selection of favored forms, and evolution through shared descent is the end result. This is a body of general statements about life, since the 1930s given in a formal version using mathematics with deductive inferences between steps. In other words, we have a body of laws, and hence a theory in the first sense just given. There is no implication here that the theory is iffy, that is in the second sense just given. We are not necessarily talking about something inherently unreliable. Of course, there are going to be additions and revisions, for instance the possibility of much greater hybridization than someone like Darwin realized, but that is another matter (Quammen 2018).