Admitting and Guilt

I've been interested in the claim widely made during the last week that by failing to fight the doping allegations against him, Lance Armstrong is implicitly admitting to cheating. There are two questions that are raised here. The first is whether you can implicitly admit something. Admitting is what philosophers of language call a speech act -- it is something you do by saying something. We often distinguish between saying and doing. We say things like "walk it like you talk it" or "actions speak louder than words." These cliches imply that there is a difference here. But there are some cases in which saying is doing. If you promise something or enter into a bet, it is the saying that is the doing. Marrying someone is another example -- recall the scene in The Princess Bride, "If you didn't say it, you didn't do it." Admitting something seems to be such an act, to admit to doing something seems to require a positive act, saying words like "I did it." Is the lack of a vigorous defense logically equivalent to such a statement? It does seem that we can make some sort of inference. Knowing how the person generally reacts to similar charges -- which is the case with Armstrong, a change in behavior is an interesting fact of the world and it does seem a legitimate basis for wondering why things are different this time. But it is weaker evidence than the explicit statement. And it is this notion of evidence that gives us our second question. Can you admit to something everyone already knows you've done? Peter Achinstein argues that proof of x is not evidence of x. He contends that evidence is an inductive notion that is connected with good reason to believe. Proof is something deductive and stronger. If you have proof, you don't need evidence. Similarly, an admission is evidence. It is someone making a statement that is designed to be very strong evidence that the person did indeed do it. It is not proof, since the admission could be false or coerced, but it is strong reason to believe the person did in fact do it. But suppose we already have extremely strong reason or even proof that he did. If we already have a rational belief in the person's guilt, then is there room for the admission to do what admissions are supposed to do? Is there a point to admitting to having done what we already know you did?