Wednesday, June 11, 2014

Extinction, creationism and presentism

An intuition a lot of people have is:

  1. The extinction of a species is a very bad thing.
On the other hand, extinction is central to the evolutionary process. Some species go extinct, making room for others, and thereby producing a greater diachronic biodiversity. Diachronic biodiversity is a very good thing, and the production of this diversity (wholly or at least to a significant degree) by natural evolutionary processes is a very good thing. This suggests:
  1. If species at least typically arise by evolutionary processes, (1) is false.

What can we say given (2)? Well, we could argue:

  1. Species at least typically arise by evolutionary processes. (Scientifically known fact)
  2. Therefore, the extinction of a species is not a very bad thing. (By 2 and 3)
I am inclined to go for this. To soften the counterintuitive consequence, we might note that what is particularly bad is extinctions where no new species are likely to evolve to fill the niche, and the kind of environmental degradation that we want to oppose not only leads to the extinction of species but stands in the way of the evolution of new species that fill the niche. Though that's an empirical question, and I don't know if it's so.

Another move is to argue:

  1. Both (1) and (2) are true.
  2. Therefore, species do not arise by evolutionary processes, even typically. (By 5)
  3. If species do not arise by evolutionary processes, creationism is true. (Since creationism is the best alternative to evolution.)
  4. So, creationism is true. (By 6 and 7)

A yet different move is to deny (2). My thinking behind (2) was based on the value of diachronic biodiversity. But perhaps diachronic biodiversity is only as valuable as I think it is if presentism is false. It is only if the past organisms in extinct species really exist, even if pastly so, that they contribute in a valuable way to biodiversity. So one might replace (2) by:

  1. If species at least typically arise by evolutionary processes and presentism is false, (1) is false.
And then one might argue:
  1. Claims (1) and (3) are true.
  2. Therefore, presentism is true. (By 9 and 10)

So I think we have three main options:

  • Deny that extinction is a very bad thing.
  • Deny evolution and affirm creationism.
  • Affirm presentism.

I should note that in (1), I am thinking of on-balance badness rather than just intrinsic badness.


Alexander R Pruss said...

I think a different way to deny (2) would be to hold a theological view different from creationism: God intended evolution to produce the species we now have. Thus, while extinction of past species wasn't a very bad thing, since it moved us to the species we now have, the extinction of present species would be a very bad thing, since present species are intended by God as endpoints for the evolutionary processes. I do not know how plausible this theological view is.

William said...

One might deny (1) in part by affirming something much more precise about what we usually would actually mourn instead:

A net decrease in the macroscopic, observable diversity of natural species on our planet is a very bad thing.

Alexander R Pruss said...

But notice that we tend to think that significant effort is worthwhile to prevent a single species' extinction. But given the number of species, a single species' extinction is insignificant for macroscopic diversity. So your suggestion would indeed require a revision of our attitudes.

William said...

By "macroscopic" I was trying to capture how the extinction of,say, plague might not be a bad thing. Plague being a microscopic species, whereas the passenger pigeon was macroscopic.

I see what you mean, though. Adding two new good species would not make the losing ofa good species a good thing, even if we linked the two somehow.

Michael Gonzalez said...

Pruss, I have a couple of questions on this one:

1) Couldn't we say that extinction of species is a bad thing, but that biodiversity is an over-riding good thing? That is to say, given a circumstance where you can have only one, but not the other, we would favor the latter. However, if biodiversity could continue by (silly example...) aliens frequently moving species to new (similar-enough) planets and letting them diversify without any of them ever going extinct, that would be even better! It would achieve both of the goods that we want. But, since this is not currently feasible, we consider the sacrifice of one good to be compensated by the attaining of a greater good.

2) I tend to disagree with you about truthmaker situations and presentism, so this next question may just get chalked up to that, but: Why would presentism negate diachronic biodiversity? It can be true now, that a great many species used to exist, but don't anymore, though they have left remnants for us to find and be fascinated by (fossils and such). Indeed, when we think of diachronic biodiversity as a good thing, there are usually two reasons for that (neither of which requires presentism to be false):

a) We find it fascinating to study what clues we have left to us, and imagine the marvelous species that used to be.

b) We treasure the end-product of natural selection's experimentation: namely: us! And our current animal companions, of course.

What we don't normally treasure is...

c)The idea that all the variety of animals which has ever existed continues to exist on an ontological par with us.

I just don't think (c) is part of what we value about diachrony. Indeed, the typical example of diachrony is language, and we tend to value a version of (a) and (b)in that case, but not of (c).

Just my thoughts.