As I was cleaning the catbox for the trip... I was thinking about David's agreement that Natural Selection was a tautology. > > For a more formal treatment on why it isn't, we'll have to wait until I get back. > > But in the meantime, food for thought: Are all tautologies inherently unreasonable? A tautology that is trivially true is... guess what, the foundation of mathematics itself! > > Euclid's first four postulates: > 1. A straight line segment can be drawn joining any two points. > > 2. Any straight line segment can be extended indefinitely in a straight line. > > 3. Given any straight line segment, a circle can be drawn having the segment as radius and one endpoint as center. > > 4. All right angles are congruent. > > Actually, TalkOrigins just supplied me with the refutation I need: > > "The real significance of this argument is not the argument itself, but that it was taken seriously by any professional philosophers at all. 'Fitness' to Darwin meant not those that survive, but those that could be expected to survive because of their adaptations and functional efficiency, when compared to others in the population. This is not a tautology, or, if it is, then so is the Newtonian equation F=ma" > -I do not think that the comparison between 'Fitness' and 'F=ma' is valid. F=ma is not circular logic, it is not redundant, it is not self confirming, all of which traits can be attributed to evolutionary fitness. According to evolutionary fitness, the simple fact that a species is extant vs. extinct is enough justify that the extant species is more fit. It is because it is. -From your link:-However, there is another, more sophisticated version, due mainly to Karl Popper [1976: sect. 37]. According to Popper, any situation where species exist is compatible with Darwinian explanation, because if those species were not adapted, they would not exist. That is, Popper says, we define adaptation as that which is sufficient for existence in a given environment. Therefore, since nothing is ruled out, the theory has no explanatory power, for everything is ruled in.-This is not true, as a number of critics of Popper have observed since (eg, Stamos [1996] [note 1]). Darwinian theory rules out quite a lot. It rules out the existence of inefficient organisms when more efficient organisms are about. It rules out change that is theoretically impossible (according to the laws of genetics, ontogeny, and molecular biology) to achieve in gradual and adaptive steps (see Dawkins [1996]). It rules out new species being established without ancestral species.-The problem with the authors argument against Popper, as I see it, is that:-1. We have no definitive criteria by which to judge efficiency other than survival(existence). Therefore, anything that exists MUST be the most efficient or fit version by the simple matter of its existence. -2. Without a full understanding of the mechanism by which an organism my spontaneously generate a new and useful adaptation, we have no definitive criteria by which to classify an adaptation as theoretically impossible. If an adaptation exists then, by definition, it MUST be theoretically possible.-3. The last statement is actually anathema to the idea of evolutionary biology. If a new species can not be established without an ancestral species, then life on earth could not have formed. (Yes, I realize that this is related more to abiogenesis than evolution which makes no deterministic claims regarding the origins of life.)