The Prime Mammal
I love reading Daniel Dennett. His voice, his pace, his examples, his metaphors, his ideas all seem tuned exactly to my taste. One of his books that I read last year–for which I finally finished my book note–was Freedom Evolves (New York : Viking, 2003, xiii + 347 pages). I was not as dazzled by it as I was by Darwin's Dangerous Idea, but I don't think that marks a deficit.
Here's a left-over excerpt that introduced a humorous idea with a serious mission, and presents an example that keeps cropping up surprisingly often in modern political discourse.
Beware of Prime Mammals
You may think you're a mammal, and that dogs and cows and whales are mammals, but really there aren't any mammals at all–there couldn't be! Here's a philosophical argument to prove it.
- Every mammal has a mammal for a mother.
- If there have been any mammals at all, there have been only a finite number of mammals.
- But if there has been even one mammal, then by (1), there have been an infinity of mammals, which contradicts (2), so there can't have been any mammals. It's a contradiction in terms.
Since we know perfectly well that there are mammals, we take this argument seriously only as a challenge to discover what fallacy is lurking within it. Something has to give. And we know, in a general way, what has to give: If you go back far enough in the family tree of any mammal, you will eventually get to the therapsids, those strange, extinct bridge species between the reptieles and the mammals. A gradual transition occurred from clear reptiles to clear mammals, with a lot of hard-to-classify intermediaries filling in the gaps. What should we do about drawing the lines across this spectrum of gradual change? Can we identify a mammal, the Prime Mammal, that didn't have a mammal for a mother, thus negating premise (1)? On what grounds? Whatever the grounds are, they will be indistinguishable from the grounds we could also use to support the verdict that that animal was not a mammal–after all, its mother was a therapsid. What should we do? We should quell our desire to draw lines. We don't need to draw lines. We can live with the quite unshocking and unmysterious fact that, you see, there were all these gradual changes that accumulated over many millions of years and eventually produced undeniable mammals.
Philosophers tend to like the idea of stopping a threatened infinite regress by identifying something that is–must be–the regress-stopper: the Prime Mammal, in this case. It often lands them in doctrines that wallow in mystery, or at least puzzlement, and, of course, it commits them to essentialism in most instances. (The Prime Mammal must be whichever mammal in the set of mammals first had all the essential mammalian features. If there is no definable essence of mammal, we're in trouble. And evolutionary biology shows us that there are no such essences.) [pp. 126–127]
The search for the Prime Mammal can easily be seen as the basis of many arguments against Darwinism favored by creationists, for example. The fruitless search for a "missing link" that would "prove" evolution is essentially a prime-mammal argument — what was the creature that came immediately before the first human, would be one way to put it. There are other forms, too, like "what was the first eye like?", or even "which came first: the chicken or the egg?" Discussion of evolution seems to abound with prime-mammal situations.
But prime-mammalism doesn't stop with evolution; it's a concept that gets applied in many forms. It's the hazard that's showing up as anti-abortionists try to get their way by claiming they can spot the moment when an egg and a sperm create a "person". Of course, prime-mammalism is not their only problem, since they've painted themselves into their corner with the notion of "ensoulment", which creates a distinct problem for them, ultimately, since there is no soul. Pretty good, though, introducing the soul: prime-mammalism and essentialism all rolled up in one!
It can be difficult to see through the prime-mammal argument in its many guises, but that ability can save a lot of time wasted in specious arguments and self-delusion.
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on Tuesday, 19 February 2008 at 15.40
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But still, leadership and public policy often require us to draw a line somewhere on the curve. Otherwise we have mobsters saying, "Life begins when I say so. That last hit wasn't a murder, it was an abortion, and since abortion is legal, I've done nothing wrong."