Ardi the Ape-Girl
Facts and Theories
While noodlng around on Ardi, the latest Ape Man that will cause us to Rethink All of Human Evolution, I came across the following on a web site called "Darwin Catholic." As Chesterton observed back when he was writing about the Scopes Trial, there is no contradiction between the two, at least insofar as "Darwin" stands in for a scientific theory and not for a social pose.
I have no idea who the blogger is, but he had a very nice summary of Ardi -- why she is important, what she does and does not mean so far as human descent is concerned. darwincatholic.blogspot.com/2009/10/ardi-looking-at-latest-missing-link.html
DarwinCatholic included the following graphic, which is as nice an illo of the fact/theory distinction as I've seen.
Facts are the dots; theories are connecting the dots. We know from Craig's Theorem in logic that we can always draw a different theory through the same body of facts. We also know that it is possible for one of the facts to be a cuckoo: it doesn't really belong with this set of facts. Folks who blather about whether evolution is a fact or a theory miss the point -- usually from either end. You may as well talk about "The Theory of Astronomy" as about "The Theory of Evolution." Evolution is not the theory. Evolution is what the theories of natural selection, common descent, etc. are trying to make sense of. A fact is something measurable -- like a fossil. The theory's job is to be true to the facts, that is, "faithful" to the facts. Truth and fact are thus two different concepts. A theory is never a fact, no matter how well supported it is by them any more than a box full of pencils is a pencil, no matter how many pencils are in the box. When we say "evolution is a fact" we are using the term "fact" in an analogous sense. We are saying the theory is so well supported that it is like a fact. This confuses the crap out of a lot of folks.
As to why Ardi is important, DarwinCatholic says:
Now we have Ardi, who despite having a big toe that would have allowed her to grip things thing her feet, has a pelvis and legs which are clearly adapted to walking upright 4.4 million years ago. Even the leg bones we have from Orrorin tugenensis 6 million years ago appear to suggest a bi-pedal posture (though it's harder to know from such incomplete remains). So with Ardi's well preserved skeleton for confirmation, it's starting to look very much like human ancestors have been bipedal for a very long time. Large brains and other adaptations are later, but it would appear that it may have been the chimps and gorillas who developed adaptations for arboreal life, and in the process shifted to walking on all fours and putting weight on the knuckles of their hands -- rather than these being features that our ancestors shed.
...which is very interesting. It begins to look not like "man is descended from chimps" but that "chimps are descended from man." All in a loosey-goosey sense, of course. They weren't men, and they weren't chimps. I've always wondered about knuckle-walkers. How did you get from that to normal hand use? It seemed like a detour. Now we have the possibility that the chimps and gorillas may actually be on their way from a bipedal ancestor to a quadrupedal descendant!
A Further Note
Noodling on Mr. DarwinCatholic's site led to this interesting meditation on the nature of species.
darwincatholic.blogspot.com/2005/10/evolution-speciation-and-nominalism.html
Darwin himself wrote in the Origin: "I look at the term species as one arbitrarily given, for the sake of convenience, to a set of individuals closely resembling each other..." This puts him squarely in the nominalist camp, which is too bad because nominalism is incoherent. And it does make somewhat problematical the "Origin of Species." Once you say that species originate in humans giving them names, what more is left? The incoherence: "closely resembling each other" in virtue of what? Grass and frogs are green. Some frogs are blue, but not green. So clearly, some resemblances matter more than others. What makes a frog "frog-like"? Even the nominalist must presuppose some form called "frog" to which this frog and that frog are more or less faithful. We might even say that this frog and that frog are facts, but "frog" is a theory that makes sense of them.
DarwinCatholic claims to be a Platonic realist, but his discussion strikes me as reasobable Aristotelia, which is good, since Aristotle had the better understanding of forms.
While noodlng around on Ardi, the latest Ape Man that will cause us to Rethink All of Human Evolution, I came across the following on a web site called "Darwin Catholic." As Chesterton observed back when he was writing about the Scopes Trial, there is no contradiction between the two, at least insofar as "Darwin" stands in for a scientific theory and not for a social pose.
I have no idea who the blogger is, but he had a very nice summary of Ardi -- why she is important, what she does and does not mean so far as human descent is concerned. darwincatholic.blogspot.com/2009/10/ardi-looking-at-latest-missing-link.html
DarwinCatholic included the following graphic, which is as nice an illo of the fact/theory distinction as I've seen.
Facts are the dots; theories are connecting the dots. We know from Craig's Theorem in logic that we can always draw a different theory through the same body of facts. We also know that it is possible for one of the facts to be a cuckoo: it doesn't really belong with this set of facts. Folks who blather about whether evolution is a fact or a theory miss the point -- usually from either end. You may as well talk about "The Theory of Astronomy" as about "The Theory of Evolution." Evolution is not the theory. Evolution is what the theories of natural selection, common descent, etc. are trying to make sense of. A fact is something measurable -- like a fossil. The theory's job is to be true to the facts, that is, "faithful" to the facts. Truth and fact are thus two different concepts. A theory is never a fact, no matter how well supported it is by them any more than a box full of pencils is a pencil, no matter how many pencils are in the box. When we say "evolution is a fact" we are using the term "fact" in an analogous sense. We are saying the theory is so well supported that it is like a fact. This confuses the crap out of a lot of folks.
As to why Ardi is important, DarwinCatholic says:
Now we have Ardi, who despite having a big toe that would have allowed her to grip things thing her feet, has a pelvis and legs which are clearly adapted to walking upright 4.4 million years ago. Even the leg bones we have from Orrorin tugenensis 6 million years ago appear to suggest a bi-pedal posture (though it's harder to know from such incomplete remains). So with Ardi's well preserved skeleton for confirmation, it's starting to look very much like human ancestors have been bipedal for a very long time. Large brains and other adaptations are later, but it would appear that it may have been the chimps and gorillas who developed adaptations for arboreal life, and in the process shifted to walking on all fours and putting weight on the knuckles of their hands -- rather than these being features that our ancestors shed.
...which is very interesting. It begins to look not like "man is descended from chimps" but that "chimps are descended from man." All in a loosey-goosey sense, of course. They weren't men, and they weren't chimps. I've always wondered about knuckle-walkers. How did you get from that to normal hand use? It seemed like a detour. Now we have the possibility that the chimps and gorillas may actually be on their way from a bipedal ancestor to a quadrupedal descendant!
A Further Note
Noodling on Mr. DarwinCatholic's site led to this interesting meditation on the nature of species.
darwincatholic.blogspot.com/2005/10/evolution-speciation-and-nominalism.html
Darwin himself wrote in the Origin: "I look at the term species as one arbitrarily given, for the sake of convenience, to a set of individuals closely resembling each other..." This puts him squarely in the nominalist camp, which is too bad because nominalism is incoherent. And it does make somewhat problematical the "Origin of Species." Once you say that species originate in humans giving them names, what more is left? The incoherence: "closely resembling each other" in virtue of what? Grass and frogs are green. Some frogs are blue, but not green. So clearly, some resemblances matter more than others. What makes a frog "frog-like"? Even the nominalist must presuppose some form called "frog" to which this frog and that frog are more or less faithful. We might even say that this frog and that frog are facts, but "frog" is a theory that makes sense of them.
DarwinCatholic claims to be a Platonic realist, but his discussion strikes me as reasobable Aristotelia, which is good, since Aristotle had the better understanding of forms.