Wednesday, October 24, 2007

Might Intelligent Design turn out to be right?

I am going to argue that for all anybody knows, evolutionary science might develop in such a way that an Intelligent Design (ID) argument would be plausible. Hence, while one might well be justified in saying that ID arguments right now do not work, one is not justified in saying that future ID arguments won't work given a fully developed evolutionary science. Moreover, our current state of biological knowledge, interpreted in an uncontroversial and friendly way, gives us relatively little, if any, reason to accept the claim that ID arguments won't work given a fully developed evolutionary science. (In the interests of full disclosure I should say that I do not think any extant ID argument succeeds in establishing the existence of a designer.)

I shall understand a successful ID argument for a design hypothesis H (say, that God has designed the world) to be an argument that starts with some biological fact F about the world going over and beyond the mere existence of life, a fact such as that the world contains intelligent life, or that the world contains the mammalian eye, or that the world contains highly complex organisms, and then argues:

  1. F is very unlikely to happen if the only processes in play are those of evolutionary biology.
  2. F is not unlikely to happen on the relevant design hypothesis H.
  3. Therefore, F provides significant evidence for the design hypothesis over and against the hypothesis that the only processes in play are those of evolutionary biology.

Assuming that before we give the argument our probability for our design hypothesis (say, that God exists and has created the world) is not too low, we're going to get a successful ID argument as soon as we can find a biological fact F satisfying (1) and (2). My claim, now, is that the present state of evolutionary science gives us little reason to believe that we will not find such a fact F. Note that the above is not the only way of formulating an ID argument. But if we are not in a position to know that no ID argument of this sort is successful, then we are likewise not in a position to know that no ID argument of some sort or otheris successful.

Let's start by considering the fact that evolutionary science gives a statistical explanation of events. It is not shown that, given an earlier state of affairs, bipeds had to evolve. All that is done in an evolutionary explanation is that an evolutionary pathway is traced out and it is argued that that pathway had a certain probability.

Next observe the fact that for most high-level biological states of affairs, we have very little in the way of estimates of estimates of the objective probability of the states of affairs arising. It would be a very, very difficult task, for instance, to estimate the probability that winged vertebrates would exist on earth given the state of things a billion years ago. Thus, although evolutionary explanations are in a significant respect statistical in nature, the statistics have by and large not been worked out.

Now, even if evolutionary science is the whole truth about biology after the initial beginning of life, there will surely be biological features of the world whose objective probability given the initial conditions is tiny. Gould talks of how if we turned the clock back and re-ran the evolutionary processes, we would get something completely different from what we have. That may or may not be true, but surely there are some biological features the probability of whose arising was tiny. For instance, consider the precise kind of pattern that a copperhead snake has on its skin. It may well be that there are myriads of patterns that would do the same job as this pattern does. It may well be that the probability that a snake-like animal would arise with that precise pattern, given the initial state of things, is tiny. (Presumably, if we conjoin enough features, we easily get cases where the probability is about as small as we like.)

Now I have two arguments for my conclusion.

Argument 1: Take a particular feature, intelligence, intelligence of the sort humans have. I think it is far beyond the current state of the art in biology to give estimates of the probability that intelligence would arise given how things were a billion years ago. Intelligence was a solution to certain evolutionary problems, but had things gone somewhat differently, these problems might not have arisen and, for all we know, many, many other solutions are possible. Moreover, we have very little in the way of estimates of the sort of organismic complexity that is needed for intelligence. All in all, we have little reason to assert that intelligence is not very unlikely given how things were a billion years ago. We just don't know how to estimate such a probability, and, unless evolutionary computing ends up yielding experimental data that shows that the evolution of intelligence is easy, it may be quite a while before we know how to estimate such a probability.

A developed evolutionary science will, presumably, assign some probability to the arising of intelligence. But I have argued we have little reason to think that this probability is not going to be very low. Suppose that this probability will in fact be very low, and developed evolutionary science discovers this. Then, a design argument, where the fact in question is the existence of intelligent life (or intelligent life on earth?), will be a good one. For we will have (1). That, by itself, is not enough. Even if it is very unlikely that the precise pattern on a copperhead should arise through evolutionary processes, there being too many other patterns that could do the job, there is no good ID argument based on this pattern, because we do not have reason to believe that a designer would not be unlikely make precisely that pattern.

However, in the case where the fact F is intelligence, and if our design hypothesis is that the world is created by the God of traditional monotheism, then the fact F is not unlikely given the existence of God, since the God of traditional monotheism is perfectly good and generous, and hence it is not unlikely that he would want to create intelligent beings (on earth? that might be an issue to consider) to bestow his goodness on. Hence, we have (2).

Thus, if we do not have much reason to deny that (1) holds of intelligence--and the present state is such that we do not--we neither have much reason to deny that a design argument based on the existence of intelligence will work. Instead, we should just suspend judgment on this. Hence, for all we know, at least one ID argument will be successful.

Argument 2: There is a myriad of biological facts, such as the precise pattern on a copperhead, each of which satisfies (1). This is no evidence at all against evolutionary biology, but just a fact about probabilistic processes like those of mutation, recombination, selection, etc. A priori improbable things happen all the time. Bob wins a lottery. A dart lands within 0.000000000001 mm of point x (this is extremely improbable whatever the point x is, but of course the dart has to land somewhere, so whenever a dart is thrown, it lands within 0.000000000001 mm of some point, and hence always something improbable happens). No surprises there. Let S be the set of very unlikely biological facts like that.

Now to have reason to hold that no ID argument for some relevant design hypothesis will be successful, one would have to have to reason to judge that none of the facts in S satisfies (2). First note that this judgment would go beyond the competence of biological science. Biological science does not estimate the probability that God, if he existed, would design a snake with such-and-such a pattern on its back. So biological science by itself would not be sufficient to establish the unavailability of an ID argument.

Now in the case of the pattern on the back of the snake, we have little reason at present to think that God would design that pattern rather than any of the many others that the snake could have had. Now in the unlikely case that we might discover that the pattern encodes some text in some natural way, the relative probability of that pattern over the others might rise. But we don't expect that to happen.

Nonetheless, I do not think we have much reason to believe that none of the facts in S satisfies (2), and we even do not have much reason to believe that none of the facts in S will be discovered to satisfy (2). So, once again, we have little reason, if any, to believe that a working ID argument won't be discovered in the future.

Conclusions: Being sure that ID will be unsuccessful is unjustified. But there is a proviso that I have to add, which was implicit in my assumption that (1) and (2) are all one needs for ID's success: unless there is good independent reason to deny the conclusion of the ID arguments (this was the assumption that the probability for H before the ID argument isn't too low).


Anonymous said...

"1 F is very unlikely to happen if the only processes in play are those of evolutionary biology.
2 F is not unlikely to happen on the relevant design hypothesis H.
3 Therefore, F provides significant evidence for the design hypothesis over and against the hypothesis that the only processes in play are those of evolutionary biology."

Isn't this the same argument as Behe's irreducuble complexity?

Alexander R Pruss said...

Behe's irreducible complexity can be seen as one way of trying to argue for (1) in some particular cases.

Martin Cooke said...

Re (1), "on earth? that might be an issue to consider," no sapient Being could know the full extent of what S/he did not already know, and so such a Being would, were S/he Creative enough, surely be likely to investigate such limits, so far as was reasonably possible. (As for the prior likelihood of such a Being, one thing we know for sure is that creative and curious intelligences can exist; whereas we have as yet no conception of how such things could arise from within a purely chemical world).

Re (2), it seems implausible, however, that "to have reason to hold that no ID argument for some relevant design hypothesis will be successful, one would have to have to reason to judge that none of the facts in S satisfies (2)." Surely some might satisfy (2) by pure chance. And we would also be more likely to notice ones that satisfied (2).

Martin Cooke said...

...sorry, I meant prior probability (not prior likelihood) in the first para there. I was thinking of likelihoods because I was saying (but not in so many words) that the likelihood of life on Earth being Designed is actually quite high. (It's such a stupid name, "likelihood":)

Incidentally, I wrote about that idea (of mine; or is it unoriginal (if it's any good it probably is), you'd surely know (?)) in this post, which I aim to tidy up into an argument for the presumption of Design at some point (if it's any good (?))

Dick said...

It is the nature of creationism/ID arguments to start with a conclusion ("God did it") and weasel backwards to premises that will work or that will somehow find openings thru the current state of affairs in evolutionary theory. If ID as it now stands is refuted in detail (as it has been), be assured that someone will put together yet another argument/book that somewhere, somehow, at some remote probability, just possibly this never-defined or undefinable "God" did it, so that supernaturalism can be rescued from naturalism. My question is this: if supernaturalism seems likely only in the darkest, deepest corners of science and at remote probabilities, is it of any real value as a valid explanation of the world? Perhaps it can provide work for philosophers, theologians, and fundamentalist preachers.

Alexander R Pruss said...

I think one upshot of my argument is that to think that ID will always fail is unscientific--it is to think that we know things about the future progress of science that we don't know. That's all. (It's not a defense of ID.)

For the record, I think there are more promising paths away from naturalism than ID provides. Thinking about objective normativity, intentionality, the cosmological argument, fine tuning, personal identity, free will, etc. can all lead away from naturalism.

Dick said...

I did not mean to imply that science provides final answers; it does not. However, once we reach a point where the probabilities are overwhelming in a particular direction or toward a particular answer, why hang everything on the remotest, unlikeliest probability that something can be salvaged from what supernaturalism has to offer? And why would anyone want to grope for something that desperately leads away from naturalism? Why is an escape from naturalism seen as desirable?

Alexander R Pruss said...

But that's the issue. I don't think science gives us any reason to estimate as low (or high) the probability that we will find a case satisfying (1) and (2).

Dick said...

I disagree. Science provides explanations that can be tested; it provides data that can be checked. ID, like its forebear creationism, seems to be the realm of charlatans. ID provides no explantory framework for anything. To say that "God did it" is not an explanation; it is an assertion. I think it is possible in science to say that we have reached a certain point with this or that data that we can move on to the next level. If we can't do that, then how did we leave astrology or phlogiston behind? We should bear in mind that someone with real data and an honest explanation of it that might yield a different answer than the standard one should always be heard. When and where to draw the line between such a person and a crackpot takes some tolerance and judgment.

Alexander R Pruss said...


I said that science gives us no reason to estimate as low the probability that we will find a case where (1) and (2) hold. Everything you said in your comment could be true, and it would have no bearing on my claim about (1) and (2).

Explanations are a species of assertion. Explanations may be more or less developed. Consider the following:

- Bob was killed by a person or persons unknown.
- Bob was killed by two persons.
- Bob was killed by Helga and Magda.
- Bob was killed by Helga and Magda with a baseball bat.
- Bob was killed by Helga and Magda with a baseball bat for his money.
- Bob was killed at 11:25 am yesterday by Helga and Magda with a baseball bat first swung by Helga and then with Magda finishing the task; both Helga and Magda needed money to pay off their gambling debts, and they were hoping to inherit the money from him, because he was their uncle.

Each of these sketches an explanation of Bob's death. The last is a more detailed sketch; the first is a less detailed sketch. But each one, I think, is explanatory. Note that the first one has very little in the way of predictive power. The last has a lot.

Dick said...

Yes, you do indeed have an ascending series of statements which you contend are mere assertions. But your assertions, and those of science, are testable, or at least can be reformulated as testable hypotheses in an experiment or, in your example, a forensic investigation.
In an analogous series of assertions in a hypothetical ID setting, statements such as
1. God did it.
2. God did it by x
3. God did it by x+1
4. God did it by x+n

No matter how detailed this series becomes, each statement from first to last, is untestable. With Occam's Razor, we can slice away the "God did it by" and be left with the explanations provided by naturalism, and these are testable.
The goal of the ID enterprise is that "God" be an intelligence (otherwise why 'intelligent' design?) and that this intelligence actually IS the Christian God (not Muslim or Hindu etc). ID is not a dispassionate philosophic or scientific inquiry. It is not even a theological inquiry. It is a religious assertion in which no answer is acceptable but the one given by ID proponents.
That science is in principle open to new explanations even after a particular matter seems to have been "settled" should not be misconstrued as an opening for spurious possibilities to keep coming forth again and again when the real world has moved on.

Alexander R Pruss said...


It is still true that even if everything you said is true, the argument that we have no reason to deny that in some case (1) and (2) hold is unaffected.

While testability is, I think, overrated (I doubt that the principle that Ockham's razor is a good guide to truth is a testable principle), and is anyway at most a criterion for a claim being scientific (of course there are other ways of knowing besides the scientific; for instance, the mathematical), it's worth noting that the claim that God did something in order to achieve some particular goal G is to some extent testable--we can see if the thing allegedly done conduces to that goal.

Dick said...

I am a scientist, not a philosopher. Perhaps I have missed what you are trying to say in 1 and 2. Would you please restate in different language the point you are trying to make?

As for your statement that "...God did something in order to achieve some particular goal G is to some extent testable--we can see if the thing allegedly done conduces to that goal.", if this be granted (and I think many scientists would not grant it), how is the achievement of the goal G to be distinguished between "God" and "Nature"? To set up a claim that 'if G, then God' seems contrived. Why can't it be that "if G, then Nature".

Alexander R Pruss said...


I thought nature doesn't have goals. :-)

As for (1) and (2), I am simply talking of conditional probabilities:
(1) P(F|the only processes are those of evolutionary biology & I) is very low;
(2) P(F|the particular design hypothesis & I) is not low.
Here I are the initial physical conditions, maybe at the time of the first living organism.

Anonymous said...

One candidate fact F is that randomly ordered polypeptide (amino acid) chains don't fold into a stable native state under physiological conditions. (Let alone do they fold into a nontoxic stable native state which performs a useful function). That is to say, the existence of proteins is a candidate fact F.

Or as they say in Peoria, "which came first, the chicken or the egg?"

Mark said...

One problem with the current ID movement is that proponents seem too quick to claim that a fact satisfies condition 1.

Such a fact (or body of observations) will only be acknowledged as requiring a non-evolutionary explanation after several generations of biologists try and fail to find a reasonable evolutionary explanation.

ID, if it is to ever be science at all, must be a very long term enterprise. It will also require an extremely tight focus on finding evolutionary explanations for biological observations (ironic, given the current tone of the ID movement).

Alexander R Pruss said...


That seems exactly right. The other problem with ID is that there isn't a well-developed theory of what exactly the designer did and why.