Patterns and Tautologies (The Circular Logic of Homologies)

I'm not really biologically inclined. I tend to stick with the more philisophical aspects of this arguement. But I would like to learn Anyway, I would like to add a (very) short summary as to why each point from AlphaOmegakid is not tautological or cicular reasoning.Please feel free to correct anything I say, it's just off my own layman's knowledge. No. Natural selection is simply one of the most popular screening processes in which evolution occurs. It is nothing more than a naturally-occuring selective pressure on a species. The existance of artificial selection should be enough to show that natural selection is not tautological. No. Homologies are simply classifications. If things weren't similar to each other, then there wouldn't be any homologies. Every single homology includes aspects that are similar. No. Vestigial features are simply no longer required. No. The geological column is simply an observation. Specific old things on the bottom, specific young things on top. That's just the way we found it. All over the planet. No. Genetic evidence was examined, and found to be similar. If it wasn't similar, it wouldn't have been evidence. The fact that it turned out to be similar, in all living things, is kind of fantastic.

It wasn't meant to be an encyclopedic discussion, only something to start from.I did more than simply state that he was wrong... that's what all the sentences after each "No." were for. I agree it wasn't much. But, well, I don't really understand his arguement in the first place."The geological column is circular reasoned."What is there to say to such a strange statement? The geological column isn't any sort of reasoning at all (let alone circular). As far as I know, it's just an observation. It's something we find as we dig holes and look at chasms all over the world.My statements aren't meant to totally refute his position. My statements are geared towards having him discuss his position and hopefully explain it a bit more. Right now, I don't really understand why he thinks any of these things are circular reasoning or tautologies.And, of course, if you think my post is lacking in information, you're free to add whatever else you'd like.

Well said.It is the well-established foundation of evolution that leads us to question our own falliable ideas before questioning the grounded philosophy. Not to say that it's impossible for the theory to be wrong, but that when something 'appears strange' the liklihood that our interpretation is in error, rather than the philosophy of the theory itself, is quite high.That's not the point I'm attempting to touch on, though. Neither do I mind that he's forgotten the '-ly' "The geological column is circularly reasoned" is a strange statement to me because the geological column is simply an observation. No one reasoned (circularly or logically) that certain fossils are on certain layers and others are on different layers still. This was not derived in any way. It was simply observed. People looked at the rock and that's what was found. People dug holes and found the same thing. People dug holes all over the earth, and found the same thing.That wasn't reasoned by any means. It was simply looked at, simply found. Found in the same way you can find gum on your shoe. The geological column came from discovery, not logical reasoning or philosophy.I understand his over-all problem lies likely with what you have described. But some of his 'defenses' don't even make sense within that framework.

Thanks for the nod. And yes, staying away from a semantics battle should be the focus of every discussion (I think, anyway). The actual issue is always much more fun to deal with. Me too Guess it's left to the waiting game, now. I've always found it best to go back to the topic where the new thread came from and post a link and possible-attention-getter from there to here. He may just not be monitoring other threads/forums, especially new ones.Or have you already tried that?

Heh... don't worry. I'll go do it.RAZD is cool, he understands being polite along with general message board conduct.(...already posted)

So you're claiming that the evidence for evolution from homologies is circular reasoning because the word 'homology' has come to mean "any similarity between characters that is due to their shared ancestry".Correct? As in, the shared ancestry is being assumed so therefore homology only comes after the theory is in place.That makes sense. But it's incorrect. The part hinting at your error is in the very Wiki sentence you quote that says "has come to mean". Which implies that the word 'homology' had a previous meaning.Let's look at the history of the homology concept: Taken from here

quote:

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The concepts of homology and analogy were well understood by the pre- (or anti-) evolutionary comparative anatomists before the general acceptance of phylogeny, and they were defined by Owen in 1843. The acceptance of evolution led to the idea that homology should be defined by common ancestry, and to the confusion between definition and explanation. The term homoplasy, introduced by Lankester in 1870, also arose from a phylogenetic explanation of homology.

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As we can see, the concept of homology (similarities of parts/structures within different organisms) was well established before evolution was introduced. It is this point in history that is being referred to when it is said that homology is strong evidence for evolution (and indeed it was one of the driving forces to accept the theory).It is only after the theory of evolution became widely accepted, because of the vast amount of other evidence as well, that the understanding of homology was discovered to come straight from the natural process of evolution itself.The history of the concept of homology even acknowledges this issues as it states "The acceptance of evolution led to the idea that homology should be defined by common ancestry, and to the confusion between definition and explanation."It is confusing, but it is not circular reasoning.The evidence and reasoning came about first, then the Theory of evolution, then the definition of 'homology' was changed to reflect it's cuase only after the overwhelming success of the Theory.Perhaps the word 'homology' should have been replaced with another, but hindsight is always 20/20.Your confusion is fully justified, but the accusation of circular reasoning is misplaced.