You Say You Want An Evolution!

[Joel]

This notion of fixity of species (or "kinds") is actually based on the ideas of the pagan Greek philosophers Plato and Aristotle, who taught that the world is eternal and that species are fixed and nothing new could arise. This philosophy was brought into Christianity thanks to some of the Church Fathers -- primarily via Augustine and later through Thomas Aquinas and Peter Abelard -- but is nowhere to be found in the Bible.

IOW, the concept of fixity of nature including the flora and fauna originates not from Scripture -- Genesis does not say that species were created with forms fixed for all time -- but comes instead from Greek philosophy and was incorporated into Christianity.

Why even AnswersinGenesis (AiG) has begun to recognize that the concept of fixity of species is based on Greek philosophy and that "not contradictory of evolutionary theory which agrees that the child is always the same species as the parent. By any test of speciation (reproduction or morphology), the parent and the immediate child are the same species. It is only after many generations that we will notice a substantial change in the Biblical "kind."

I'm not seeing how evolution contradicts Aristotle in that manner. No one is claiming that any individual member of a species turned into a different species, right? Every individual fish was a fish for its whole life. "Every entity" still had its essence. And the "eternal" there is not accurate of Aristotle. You can cut down a tree and burn it, so that the essential properties of a tree are lost. But that means that the tree ceases to be. The essence of the tree is immutable only in the sense that as long as it is a tree, it must have the properties essential to being a tree. To remove/destroy those properties is to destroy the tree.

If instead of an individual tree you speak of trees in general, then you are talking about a (Aristotelian) species or genus, which has an essence: the set of properties that are true of every tree. And of course the essence of a species cannot change. If you changed the essential properties then you would be talking about a different species. Or if all trees became extinct, that wouldn't destroy the species. It would just mean that there no longer exists any individual of that species.

For example, suppose modern tigers are the descendants of saber-toothed tigers (I don't know whether that is true, but just suppose for the sake of argument). That doesn't mean the species (in the Aristotelian sense) "saber-tooth tiger" changed into the species "modern tiger". The species "saber-tooth tiger" still 'exists' (has its essential definition), because we can still predicate true things about it, such as, "Saber-tooth tigers are extinct." In that sense the essence of a species (like "saber-tooth tiger") is immutable.

Did Aristotle think that no individuals of a new species could come to be? I don't think so. 'Sculptures of Socrates' is a species, and before the first one was sculpted, there had never been any.

[rogue06]

I'm not seeing how evolution contradicts Aristotle in that manner. No one is claiming that any individual member of a species turned into a different species, right? Every individual fish was a fish for its whole life. "Every entity" still had its essence. And the "eternal" there is not accurate of Aristotle. You can cut down a tree and burn it, so that the essential properties of a tree are lost. But that means that the tree ceases to be. The essence of the tree is immutable only in the sense that as long as it is a tree, it must have the properties essential to being a tree. To remove/destroy those properties is to destroy the tree.

If instead of an individual tree you speak of trees in general, then you are talking about a (Aristotelian) species or genus, which has an essence: the set of properties that are true of every tree. And of course the essence of a species cannot change. If you changed the essential properties then you would be talking about a different species. Or if all trees became extinct, that wouldn't destroy the species. It would just mean that there no longer exists any individual of that species.

For example, suppose modern tigers are the descendants of saber-toothed tigers (I don't know whether that is true, but just suppose for the sake of argument). That doesn't mean the species (in the Aristotelian sense) "saber-tooth tiger" changed into the species "modern tiger". The species "saber-tooth tiger" still 'exists' (has its essential definition), because we can still predicate true things about it, such as, "Saber-tooth tigers are extinct." In that sense the essence of a species (like "saber-tooth tiger") is immutable.

Did Aristotle think that no individuals of a new species could come to be? I don't think so. 'Sculptures of Socrates' is a species, and before the first one was sculpted, there had never been any.

They're not saying that evolution contradicts Aristotle but that the concept of fixity of species is not Biblical and was imported from Aristotle.

[Joel]

They're not saying that evolution contradicts Aristotle but that the concept of fixity of species is not Biblical and was imported from Aristotle.

Imported from Aristotle how? My point is that essence of an individual or species implies nothing about whether an individual can have offspring (or distant offspring) that are different from the parent. Aristotle would refer to "musical man" as a species of the genus "man". (Genus and species were not biological terms.) Musical man and unmusical man are different species (of man). And clearly a musical man could have unmusical parents, thus the child and parent would be in (those) different species. And an individual unmusical man can become a musical man (thus the unmusical man ceases to be). Species (for Aristotle) are not fixed in either of those senses. A claim about constants/fixity in biological reproduction seems unrelated.

Did the people being referred to misunderstand Aristotle? Or perhaps the people who are today commenting on those past people are misunderstanding those past people?

[rogue06]

Imported from Aristotle how?

This philosophy was brought into Christianity thanks to some of the Church Fathers -- primarily via Augustine and later through Thomas Aquinas and Peter Abelard -- but is nowhere to be found in the Bible.

Whether or not they misunderstood Aristotle is kind of beside the point. They're arguing (and I agree) that the whole concept of fixity of species is not Biblical.

[seer]

Whether or not they misunderstood Aristotle is kind of beside the point. They're arguing (and I agree) that the whole concept of fixity of species is not Biblical.

So given enough time humans could become something that is not human.

[rogue06]

So given enough time humans could become something that is not human.

Not exactly. Taxologically speaking a bird is still considered a dinosaur for instance.

[Joel]

Not exactly. Taxologically speaking a bird is still considered a dinosaur for instance.

Interesting. So then it's true to say there are dinosaurs still living today. Or: Dinosaurs are not extinct.

I assume there are other cases where "descendant of" does not imply "is a" (or "is a subset of")?
What makes the difference?

[rogue06]

Interesting. So then it's true to say there are dinosaurs still living today. Or: Dinosaurs are not extinct.

I assume there are other cases where "descendant of" does not imply "is a" (or "is a subset of")?
What makes the difference?

To be accurate it is usually phrased that there are no extant non-avian dinosaurs.

[seer]

Not exactly. Taxologically speaking a bird is still considered a dinosaur for instance.

So we are still apes? I mean if whales came from a dog like creature how is a whale still a dog?

[rogue06]

So we are still apes? I mean if whales came from a dog like creature how is a whale still a dog?

Taxonomically speaking humans are a type of ape just like we're a type of mammal.

And whales did not come from dogs.

[seer]

Taxonomically speaking humans are a type of ape just like we're a type of mammal.

And whales did not come from dogs.

I said dog like. The Pakicetus?

[Amidoingit]

So given enough time humans could become something that is not human.

Well the driver behind evolution is the accumulation of random mutations amongst the population, so while time is a requirement it doesn't necessarily mean evolution will occur. There are species that have remain largely unchanged for long periods of time.

[rogue06]

I said dog like. The Pakicetus?

"Dog like" is pretty nebulous. Actually a whale's closest relative appears to be hippos.

As an aside the remains of a new "walking whale" has recently been discovered in Peru indicating that they were very capable swimmers which until this discovery was uncertain: Four-legged prehistoric whale fossil found in Peru

[rogue06]

Well the driver behind evolution is the accumulation of random mutations amongst the population, so while time is a requirement it doesn't necessarily mean evolution will occur. There are species that have remain largely unchanged for long periods of time.

Welcome to Tweb

The idea of "living fossils" is a bit of a misnomer and misleading. Here are two articles discussing the issue:

The Falsity of Living Fossils

The Rise and Fall of the Living Fossil

For a more specific example I discuss just how much coelacanths have changed over time in this post.

Another example are crocodiles or crocidilians which had some pretty wild ancestors in their lineage since at various times they filled a variety of ecological niches that they don't occupy today. For instance, some ancient species were bipedal, some were arboreal (lived in trees), some lived in extremely arid environments, some had boar-like tusks, some were herbivores or ate grubs, and some had fish-like tails^[1]










1. Here's a cool article about five strange types of extinct crocs discovered in 2009 in Niger with such nicknames as "BoarCroc," "DogCrock," "RatCroc," "PancakeCroc," "DuckCrock"

[seer]

"Dog like" is pretty nebulous. Actually a whale's closest relative appears to be hippos.

As an aside the remains of a new "walking whale" has recently been discovered in Peru indicating that they were very capable swimmers which until this discovery was uncertain: Four-legged prehistoric whale fossil found in Peru

OK rogue, so back to the Adam question. Given that Scripture is clear that all human beings alive today are descendants of one man Adam (who lived between 5-16 thousand years ago given gaps in the Biblical geologies), how can that be reconciled with the theory of evolution? You hold a high regard for the theory but it is clearly at odds with the Biblical claims. I think the Christian must choose between the two.