Saturday 17 March 2012

Natural selection is a metaphysical assumption, therefore cannot be refuted


Further to my recent postings on this topic, I solicit responses to the fact - as it seems to me, a practitioner - that Natural Selection is a metaphysical assumption which cannot be refuted.

For example here are two big things (ahem) which have no decent explanation from natural selection but which are (ahem) very obvious:

The existence of sexes (yes, I know WH Hamilton's ideas, but really nobody believes them).

The existence and attractiveness of prominent breasts in adult women (no decent theories which satisfy minimal biological constraints).

Yet - the failure to come-up with decent theories for such major bio-cultural phenomena as the sexes and large human breasts has not even scratched the fact that it is assumed that eventually some such theory will be discovered or invented.

In practice, Natural Selection cannot be refuted by science (or by evidence): it's validity is assumed - as is the case for all meta-scientific (metaphysical) assumptions.


[P.S Commenters please note: The above posting has exhausted the permissible quota of smutty double entendres / witty wordplay for this topic. ]



Dennis Mangan said...

Re: breasts, they are a prominent signal that the bearer is young and fertile - or not, as the case may be. After all, not all breasts are considered attractive. Therefore I see no reason why natural selection can't explain the preference.

Bruce Charlton said...

@Dennis - thanks for accepting the challenge.

But it doesn't work.

Adult women's breasts look like lactating breasts in other primates, lactating breasts are a sign of infertility (because under ancestral conditions breast-feeding was almost wholly effective as a contraceptive) therefore lactating-looking breasts are (or ought to be) sexually un-attractive.

The first ancestral women to have permanently lactating-looking breasts would have been *less* attractive as a mate - so how did they evolve?

Thursday said...

Aren't you dismissing The Red Queen hypothesis a bit too quickly? Just taking a quick look at Wikipedia, there have apparently been studies that show that exclusively asexual reproduction leads to significant problems with parasites among both snails and worms.

I'd also note that there is another process going on at the same time as natural selection and that is sexual selection, which has its own rules.

Bruce Charlton said...

@Thursday - I know of this work - indeed Matt Ridley's The Red Queen was the book that caused me to change my academic discipline from Epidemiology to Evolutionary Psychology. But the evolutionary barrier to the emergence of mandatory sexual reproduction is formidable.

Sexual Selection is a sub-type of Natural Selection (not a different mechanism) - both are underpinned by differential reproductive success.

Kristor said...

I think you are correct that natural selection is a metaphysical presupposition that cannot be refuted. After all, it boils down to the notion that some things happen, and other incompossible alternatives therefore do not. How can this be disputed? And, how can it possibly explain anything that does happen?

Bruce Charlton said...

@Kristor. Indeed. And then so are many other scientific theories or approaches.

Yet at least in the past and for a while science very clearly *worked* (the world was changed) - so it is possible, it seems, that assumptions can be linked to obviousness, to common sense and common experience.

But probably the way that science worked was the opposite from how people thought it worked. People thought it worked because scientific assumptions were valid, but probably scientific assumptions were valid only insofar as science worked.

As soon as the validity of assumptions was assumed, then science stopped 'working' - that it, was no longer underwritten by common experience - but was pseudo-underwritten by more-science.

That is where we are now. The validity of science is guraranteed by science - and common sense and common experience are excluded. Science now does not 'work' by normal human criteria; rather normal human criteria are judged (and rejected) by 'science'.

Of course, this modern science is not what was meant by science 100 years ago - modern science is indeed something like the opposite of real science.

J said...

Well fed lactating women are not infertile, on the contrary. It signals that the woman is in excellent physical condition.

Bruce Charlton said...

@J - you are correct for MODERN conditions, in particular modern diets which are nutritionally concentrated and high in fat - but the assumption is that we are talking about hunter-gatherer conditions where the diet is very much less dense, and meat is almost completely lean. Under HG conditions lactation is nearly always contraceptive.