Many people bring forth the argument that the chances of life, especially

Read another response by Nicholas D. Smith
Read another response about Religion
Many people bring forth the argument that the chances of life, especially intelligent human life, occurring are so ridiculously improbable that the only way to explain it is to bring a creator into the picture. I've heard various figures thrown around and grains of sand in the universe brought in to explain how unlikely it is. But is the actual science behind the probability sound? And do you think that this is a good reason to believe in a creator? And what about a rational, logical argument explaining how this is not a very good reason? Thanks.

First of all, it is nonsense to try to assess the probability of intelligent human life occurring unless we first stipulate what the prior conditions are.

According to evolutionary theory, human beings and other living things are the result of genetic mutations that occur within prior life forms, which are then selected as a result of added fitness within a certain environment. Given the nature of this process, it is all but senseless to assess the (prior) probability that some specific life form would emerge from a (random) mutation in the prior life form, given all of the variables that are pertinent to fitness within a given environment. So if someone thinks they can calculate this as a real probability, I expect they are simply making up the values on which their calculations are based. This is no way to do things!

Now, there may be calculations we can apply to very specific conditions at very specific places and times, with respect the the likelihood that some very specific string of molecules might come together in that environment. People have debated about this with respect the the very origin of life in what has been called the "primordial soup." But a lot of this is also pure speculation, because we don't really know all of the exact conditions in all places and times within that "soup." So I don't find this very useful, either.

Finally, there is something in the logicl of the argument that strikes me as simply fallacious. The argument sseems to go like this:

(1) The likelihood that life (or life form X) would come about in these conditions is absurdly low.
(2) That likelihood goes way up if we assume that the emergence of life (or life form X) was the product of divine intervention.
(3) Hence, it is reasonable to suppose that divine intervention is the real cause of the emergence of life (or life form X) in those circumstances.

There is a lot wrong with this, even if we accept premise 1:

(A) What are the (prior) probabilities of the existence or emergence of a divinity, whose will would be precisely what it needed to be to want life (or life form X) to come about? And if these are incalculable (as I suspect), then why should we accept premise 2? It seems to me that one might suspect that the addition of the potential improbability of the appearance of a divinity (if that notion is even cogent, which some doubt, but which--if not--deduces that probability to zero!) would actually make all of the pertinent probabilities go even lower, rather than higher.

(B) Equally importantly, wwe should reject the inference. Notice what this way of reasoning would do to lottery winners. I am told the Powerball lottery has probabilities of 1 in 80,000,000 that anyone will win it. That's pretty unlikely, right? But if we now add something like premise 2 and make the inference to some version of 3, we will learn that all "lotteries" are actually cheats, because it is more plausible to suppose that some God prefers to pick the winners of the "lotteries" instead of allowing chance to generate the outcome.

I expect that many lottery winners feel that God has blessed them with the win. But that sentiment does not mean that we should accept such reasoning! Improbable stuff happens all the time. Even given the existence of intelligent life and all the rest, what would you say are the prior probabilities that you would ask this question and I would give this exact answer? Who knows, but on the wway of calculating that this sort of argument proposes, my guess is that someone would conclude that it is only the result of God's will that I gave this answer at this time to your question!

(I don't think so...)

Related Terms