These Creationists think they have a crushing complaint about Darwinism -- it's based on a tautology:
"Waddington is not alone in his assessment of the serious problems facing evolution as a result of natural selection having been shown to be a circular argument. G.A. Peseley joined the ranks of those criticizing natural selection as evolution’s mechanism when he stated:
"'One of the most frequent objections against the theory of natural selection is that it is a sophisticated tautology. Most evolutionary biologists seem unconcerned about the charge and make only a token effort to explain the tautology away. The remainder, such as Professors Waddington and Simpson, will simply concede the fact. For them, natural selection is a tautology which states a heretofore unrecognized relation: the fittest—defined as those who will leave the most offspring — will leave the most offspring.
"'What is most unsettling is that some evolutionary biologists have no qualms about proposing tautologies as explanations. One would immediately reject any lexicographer who tried to define a word by the same word, or a thinker who merely restated his proposition, or any other instance of gross redundancy; yet no one seems scandalized that men of science should be satisfied with a major principle which is no more than a tautology (1982, 38:74).'"
I know what they mean! Think of the notorious pseudo-scientist Sir Isaac Newton, who declared that an object will continue in uniform, straight-line motion (rest being a special case of this) unless acted upon by a force. And how do we know that's right? How do we find out if a force is present? We use F=MA, in other words, we detect a force by seeing if some mass is deviating from uniform, straight-line motion! As the famed physicist Sir Arthur Eddington re-phrased these two laws, "Objects move in straight lines unless they don't."
This is not a criticism of Newton, but of the afore-mentioned Creationists. They, along with many others, have not realized that such tautologies are crucial in a science, for they set up the concepts that will direct further research. Of course, they themselves are not subject to empirical investigation -- they are the assumptions underlying empirical work, which never starts from a blank slate -- to do so is impossible, in fact. You can't set out with zero conceptual apparatus and "just start testin' sh*t" -- how would you ever have any idea what you were testing?
Oh, and the silly Mr. G.A. Peseley, whoever he is, seems unaware that a dictionary is a giant tautological network!