Friday, June 05, 2009

Bad Reason #9 – It’s just a theory

This is the ninth article in my series of 10 bad reasons to reject evolution, this post deals with the objection that "Evolution is just a theory, not a fact".

Well evolution is a theory. It is also a fact. And facts and theories are different things, not rungs in a hierarchy of increasing certainty. Facts are the world's data. Theories are structures of ideas that explain and interpret facts. Facts don't go away when scientists debate rival theories to explain them. Einstein's theory of gravitation replaced Newton's in this century, but apples didn't suspend themselves in mid-air, pending the outcome. And humans evolved from ape-like ancestors whether they did so by Darwin's proposed mechanism or by some other yet to be discovered.

Moreover, "fact" doesn't mean "absolute certainty"; there's no such thing in an exciting and complex world. The final proofs of logic and mathematics flow deductively from stated premises and achieve certainty only because they are not about the empirical world. Biologists make no claim for perpetual truth, though creationists often do (and then attack science falsely for a style of argument that they themselves favour). In science "fact" can only mean "confirmed to such a degree that it would be perverse to withhold provisional consent." I suppose that apples might start to rise tomorrow, but the possibility does not merit equal time in physics classrooms.

So this objection is no more than an epic failure to understand the scientific method and to appreciate the difference between facts and theories, the following quote is from H. J. Muller and sums this up far better than I could.

The honest scientist, like the philosopher, will tell you that nothing whatever can be or has been proved with fully 100% certainty, not even that you or I exist, nor anyone except himself, since he might be dreaming the whole thing. Thus there is no sharp line between speculation, hypothesis, theory, principle, and fact, but only a difference along a sliding scale, in the degree of probability of the idea. When we say a thing is a fact, then, we only mean that its probability is an extremely high one: so high that we are not bothered by doubt about it and are ready to act accordingly. Now in this use of the term fact, the only proper one, evolution is a fact. For the evidence in favour of it is as voluminous, diverse, and convincing as in the case of any other well established fact of science concerning the existence of things that cannot be directly seen, such as atoms, neutrons, or solar gravitation.

So enormous, ramifying, and consistent has the evidence for evolution become that if anyone could now disprove it, I should have my conception of the orderliness of the universe so shaken as to lead me to doubt even my own existence. If you like, then, I will grant you that in an absolute sense evolution is not a fact, or rather, that it is no more a fact than that you are hearing or reading these words.

- H. J. Muller, "One Hundred Years without Darwin Are Enough" School Science and Mathematics 59, 304-305. (1959) reprinted in Evolution versus Creationism op cit.

Another common misconception among the choirs of objectors is that evolution can't explain the origin of life and that somehow this straw man argument somehow discredits what it does explain perfectly adequately i.e. how simple life becomes complex life without the need for a "designer". Again an argument from ignorance, evolution as a theory does not address itself to the origins of life no more than the germ theory of disease addresses why apples fall from trees. There are however scientific theories that address the origins of life from non-animate matter, they fall under the heading of Abiogenesis.

1 comment:


Anyone who believes in creation is irrational starting with Adam & Eve.