Sunday, September 28, 2008

 

Purpose and Science


This is just one of my musings about philosophy that is, doubtless, more interesting to me than to others ... but it's my blog! Feel free to spare your glazed-overed eyes.

There is a common argument for atheism that runs like this:

If purpose was part of the universe then there's no reason at all why science couldn't have detected it. It follows that, if there was purpose to the universe, then we would have scientific evidence of purpose. The facile nonsense of Intelligent Design Creationism notwithstanding, we don't have scientific evidence for purpose, therefore [it is reasonable to conclude that] there is no purpose to the universe [and, therefore, that there is no God].

The parts of the above in brackets are intended to indicate that this argument is stated with varying degrees of certainty and toward various conclusions.

Now, I'm an Apathetic Agnostic ("We don't know and we don't care") . Among the "tenets" of apathetic agnosticism (if we cared enough to actually hold to something as tiring as a tenet) is:

To all appearances, any purported Supreme Being is indifferent to our Universe and to its inhabitants. If there is a God, and that God does not appear to care, then there is no reason to concern ourselves with whether or not a Supreme Being exists.

In short, I agree with the claim that there is no apparent purpose to the universe but I disagree with the atheistic conclusion from that appearance. Okay, you may be asking yourself, but why bring it up? Well it turns out that I, at least, have a purpose and that is to discuss a point made by Elliott Sober, one of the best philosophers of science at work today, in his excellent but difficult (for me, at least) book, Evidence and Evolution: The Logic Behind the Science.

The atheist argument above actually takes the form of what Sober calls a "probabilistic modus tollens." The standard modus tollens is a rule of deductive reasoning as follows:

If H, then O
not O
————————————
not H


... which reads: if the hypothesis H entails the observation O, and O turns out to be false, then it follows that H is false. The sticking point is that "entails." In order for the above syllogism to be valid, it must be certain that, if H is true, you will make the observation O.

But science does not work like that. Science is fallibilistic and incomplete. That is the basis of the common saying "the absence of evidence is not evidence of absence." Otherwise, it would follow, for example, that the universe was not expanding until Edwin Hubble made his observations of stellar redshifts, since, until then, there was an absence of evidence for expansion.

This aspect of science means that the very best that the atheistic argument can state is:

Pr(O \ H) is very high
not O
————————————————————
not H


... which reads: if the hypothesis H says that O will very probably be true, and the scientific observation, O, is not made, then H is false [or, at least, very improbable and, therefore, should be rejected]. Sober explains the problem:

Friends of [probabilistic modus tollens] need to say where the probability cutoff for rejection is located. How low must Pr(O H) be for O to justify rejecting H? Richard Dawkins [The Blind Watchmaker, p. 144-46] addresses this question in the context of discussing how theories of the origin of life should be evaluated. He says that an acceptable theory can say that the origin of life on Earth was somewhat improbable, but it cannot go too far. If there are n planets in the universe that are "suitable" locales for life to originate, then an acceptable theory of the origin of life on Earth must say that that event had a probability of at least 1/n. Theories that say that terrestrial life was less probable than this should be rejected. Creationists also have set cutoffs. For example, Henry Morris [King of Creation] says that theories that assign to an event a probability less than 1/10111 should be rejected, and William Dembski [The Design Revolution] says that a theory that assigns to a "specified event" (a technical term in Dembski's framework) a probability less than 1/10150 should be rejected. Morris and Dembski obtain these numbers by attempting to calculate how many times elementary particles could have changed state since the universe began.

Dawkins, Dembski, and Morris have all made the same mistake. It isn't that they have glommed on to the wrong cutoff. The problem is deeper: There is no such cutoff. Probabilistic modus tollens is an incorrect form of inference. Lots of perfectly reasonable hypotheses say that the observations are very improbable.

What is more, it does not follow that the failure to observe O can even be considered as evidence against H. Converting the probabilistic modus tollens to an "evidential probabilistic modus tollens," the argument now takes the form:

Pr(O \ H) is very high
not O
———————————————————————————
not O is evidence against H


... which reads: if the hypothesis H says that O will very probably be true, and the scientific observation, O, is not made, then that failure is evidence against H. But consider the counterexample Sober gives:

Suppose I send my valet to bring me one of my urns. I want to test the hypothesis (H) that the urn he returns with contains 0.2 percent white balls. I draw a ball from the urn and find that it is white. Is this evidence against H? It may not be. Suppose I have only two urns; one of them contains 0.2 percent white balls, while the other contains 0.01 percent white balls. In this instance, drawing a white ball is evidence in favor of H, not evidence against it.

In short, in order to make a claim about the evidential value of the failure to make an observation, you need to do more than test the hypothesis against its negation.

[J]udgments about evidential meaning are essentially contrastive. To decide whether an observation is evidence against H, you need to know what the alternative hypotheses are; to test a hypothesis requires testing it against alternatives. In the story about the valet, observing a white ball is very improbable according to H, but in fact that outcome is evidence in favor of H, not evidence against it. This is because O is even more improbable according to the alternative hypothesis.

Simply saying that you are testing a "purposeful" universe against a "purposeless" one doesn't help because you merely run up against the Duhem–Quine thesis, which holds that any test of a hypothesis necessarily entails auxiliary hypotheses that, unless they are also being tested, may affect the outcome -- such as the number of urns involved and the percentage of white balls they hold. In other words, before the absence of scientific evidence of purpose could justify an evidentiary claim, there would have to be a comprehensive account, including all relevant auxiliary hypotheses, of what a purposeful universe would look like. Besides the difficulty, if not impossibility, of constructing such a complete theory of purpose, the very comprehensiveness of the theory would prevent the result from constituting a general refutation of purpose. The evidence of absence would only apply to the now narrow collection of hypotheses and auxiliary hypotheses.

In fact, the atheist argument runs up against the very problem that the IDers face when they claim to demonstrate disembodied "design." Without knowledge of the motives and abilities of the purported "designer" or "purposer," there is no way to differentiate the action (or non-action) of such a being from our state of ignorance.

There is much more that can be said on the subject and Sober exhaustively exposes the philosophical weaknesses of ID, much of which applies as well to this argument for atheism. But it is only fair to ask why, if I think that the argument fails logically and scientifically, do I then accept the lack of apparent purpose in the universe as any basis for agnosticism? For one thing, the question that the lack of evidence bears on is (perhaps subtlety) different. Instead of considering whether there is, in fact, purpose behind the universe, the issue is whether whatever purpose-giver there may be is interested in humans knowing and reacting with that purpose. Given that any being capable of imparting purpose to an entire universe is presumably capable of making its existence and intentions known in unambiguous ways, a tentative conclusion that any such being is uninterested in human participation is, if not logically or scientifically rigorous, at least not unreasonable.

And that leads to my final point. Science is not an appropriate tool to determine matters that are, ultimately, nothing more than personal preferences as to how to approach life. Certainly, science's methods and results can be taken into account by anyone considering those preferences but, in the end, our weltanschauung is made up of a bundle of emotions, attitudes learned in childhood and unconscious value judgments with, at most, only partial imput by reason. Furthermore, science delivers information on what is, not what ought to be. Any assertion that we should determine our values and preferences by scientific rationalism is not, itself, a result of the scientific method, making the claim circular and self-defeating.

When it comes to values, we're on our own.
.

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Comments:
I also bought the same book by Sober, but have not really had any time to read much of it so far (you were actually the first person to reveal the existence of the book [to me] on this very blog). From the little I HAVE read and from some online reviews, I know that it is going to be a hard read for someone like me. But I also know that it will be a rewarding one, so I will persist.

For interested readers who may not be familiar with Sober, I can thouroughly recommend his online article "What is wrong with intelligent design?" at:
http://philosophy.wisc.edu/sober/what%27s%20wrong%20with%20id%20qrb%202007.pdf
 
I agree on the probability point. The low point of the God delusion was the ultimate 747 argument. The argument is nonsense when creationists make it, and nonsense when Dawkins makes it.

I am however still an atheist. I never think much about arguments for atheism. After all I am an atheist because I don't believe in any gods, so the matter of gods is really not so important to me.


I called myself an agnostic for a while, but then I realized, the wor atheist describes a category of people. I don't get to choose if I'm an atheist. If I believe in gods I'm not, if I don't I am.

So I'm an atheist, and so is my 18 months old son. He doesn't know about gods, so it follows he is an atheist.
 
The first 108 pages on scientific evidence were the toughest of Sober's book, mainly because I had forgotten what little probability and statistics I ever knew. The second chapter on ID is much more familiar territory and going much faster.

I agree with Wilkins that there is a difference between atheism and agnosticism but I'm not going to get involved in another angel-dance around the head of that pin.
 
As an apathetic agnostic I would probably agree with you if I could have been bothered to read the post, particularly as it seems to have been based on a Sober consideration of the arguments and evidence.

Having escaped the clutches of the Church of England, though, I have no urge to join another, whether apathetically agnostic or not. Of course, "clutches" is probably too strong a word for the Church of England since the sanctions for leaving seemed to range from mildly reproachful looks and comments to utter indifference.
 
One of these decades I'll think of a sufficiently interesting and long-winded way of saying this, that I'll make a whole blog-post out of it, but in the mean time, I'll repeat the comment that I know I've dropped various places before:

Q: Am I atheist or agnostic?
A: Depending on which god you want my opinion on, y reactions range from "Obviously not!" through "Could be, so get back to me when you have actual evidence", to "Not meaningful enough for there to be any evidence, either way".
So w.r.t the entire set of gods, I am agnostic in that I cannot say for sure that it is empty. But I identify as atheist, since that expresses my view towards most of the popular gods, of relevance in our culture.

Note to Ian: Geez, excommunication just ain't what it used to be, is it?
 
Many religions require that the universe in general, and humans in particular, are the end result of some purposeful creation.

Many religions claim that they can detect God's purpose.

Science has not found any evidence of purpose. From a scientific perspective, it looks like life has no purpose beyond the fact that it simply exists.

Therefore, the evidence of science is in conflict with one of the core beliefs found in many religions.

The absence of evidence of purpose is not offered as proof of the non-existence of God. All it does is explain why so many theists are uncomfortable with the implications of modern science and the practice of methodological naturalism.

Here's how the argument actually goes in many cases.

-----------
My religions says that there is evidence of purpose in the universe.

Science says there's no evidence of purpose.

Therefore, science and my religon are in conflict and one of them has to be wrong.
-----------

Ken Miller is one of many theists who have described the conflict. He writes in "Not Just a Theory" (p. 111) ...

We live in a country where nearly 90 percent of the people profess a belief in God, and I would argue that just about every one of them, myself included, believes that there is meaning to their lives, order in the universe, and a purpose to our existence. In that very distinct sense it can be said that a great majority of Americans believe in something like an "intelligent design" to the world around us. A a result the existence of arguments for design will command their immediate sympathy. After all, what's the alternative? Unintelligent design? Random design? ot no design at all? A universe of molecules weaving through space and time without meaning or purpose?

I believe that what science strongly suggests is, "a universe of molecules weaving through space and time without meaning or purpose."

Miller goes on to explain why the naive versions of intelligent design should not attract sympathy. Then he explains why he thinks there's scientific evidence of meaning and purpose. As you know, John, his explanation is similar to that of Simon Conway Morris and Francis Collins. For Miller, one big piece of this "evidence" is the fine tuning argument.

I think that science conflicts with Miller's version of Roman Catholicism.
 
Science has not found any evidence of purpose.

No, Larry, as Sober demonstrates, science, as it is understood in the modern sense, has made no attempt to discover, nor made any valid inference from, any scientific evidence for "purpose." It's hardly surprising not to find what you are not looking for and probably could not find if you were looking.

The absence of evidence of purpose is not offered as proof of the non-existence of God.

You may or may not (you are no more consistent than any other human being) have made that argument but are you seriously claiming that no one ever has? In any case, if you are not arguing against God, that is one sizable auxiliary hypothesis that you are ignoring.

I believe that what science strongly suggests is, "a universe of molecules weaving through space and time without meaning or purpose."

Yes, I'm aware that is your personal preference based on your atheism. It's Miller's persoal preference, based on his belief in God (as he, at least, makes clear in that quote you give), to think that the results of science at least permit the possibility of a purpose to life. Science, however, does not answer which of your preferences are right.

You're free to argue what you perceive as the "larger lessons" of science as part of your philosophical case, just a Miller is free to argue for larger lessons from science in support of his theism. Neither of you are actually doing science when you do so.

I think that science conflicts with Miller's version of Roman Catholicism.

So, your auxiliary hypothesis is that you know Miller's version of Roman Catholicism better than he does?
 
Oh, yes ...

Many religions require that the universe in general, and humans in particular, are the end result of some purposeful creation.

Many religions claim that they can detect God's purpose.


And, of course, even assuming it could be shown that the latter is false, that is not evidence against the former.
 
John Pieret says,

Many religions require that the universe in general, and humans in particular, are the end result of some purposeful creation.

Many religions claim that they can detect God's purpose.

And, of course, even assuming it could be shown that the latter is false, that is not evidence against the former.


That's correct. You based your initial argument, as did Sober, on your understanding that this was the correct form of the argument.

While it may be true that some people are trying to make the case as you put it, many are not. What I'm trying to do is show that there is no scientific evidence of purpose and therefore the assumption that there's evidence of purpose in the universe is incorrect.

I can't rule out the possibility that there is completely undetectable purpose in the universe but as soon as religious proponents make a scientific claim (there is evidence of purpose) they cross over into the magisterium of science.

Whenever they do that they have been shown to be wrong.

I admit that I make fun of the fallback position; namely, that there's purpose in the universe but we just can't see any evidence for it.

John, either there is evidence of purpose in the universe or there is not. You claim that scientists who see no evidence of purpose are letting their personal beliefs influence their powers of observations. That's a very serious charge.

Do you feel the same way about those of us who deny there's any evidence of spaceships that kidnap people? Do you feel the same way about scientists who deny that there's any evidence homeopathic solutions can cure you? Do you feel the some way about people who say there's no evidence of the tooth fairy?

Are all these people letting their philosophical positions influence their powers of scientific observations?

So, your auxiliary hypothesis is that you know Miller's version of Roman Catholicism better than he does?

No. My position is that I know science better then he does and it is not scientific to assume that the fine tuning argument has any scientific validity. It is not scientific to assume that examples of convergence lead to the conclusion of underlying purpose. It is not scientific to claim that the world knew we were coming.

And it is definitely not science to disguise ones philosophy under the banner of "evolutionary cosmology" implying that it has scientific validity.
 
... as soon as religious proponents make a scientific claim (there is evidence of purpose) they cross over into the magisterium of science.

If they make the claim as if it were science, they certainly do. They are, as I already noted, as free as you are to include the results of science (including the "gaps" in science) in their philosophical arguments, when clearly labeled as such.

You claim that scientists who see no evidence of purpose are letting their personal beliefs influence their powers of observations. That's a very serious charge.

No, it's not. Scientists are as free as anyone to be wrong in their philosophy. The case I'm making is that there have been no "observations" of lack of purpose because science (at the very least, as of today) cannot make any such observations scientifically.

Do you feel the same way about those of us who deny there's any evidence of spaceships that kidnap people?

No, because we have people and an atmoshere and alleged landing sites to investigate empirically. In short, you have a full set of auxillary hypotheses that can be tested and compared. But, even then, I wouldn't make the mistake of thinking that evidence against those particular claims as to specified times and places is evidence for or against the existence of spaceships and spaceship makers somewhere the universe. Similarly, in the case of the tooth fairy, there is an alternative hypotheses (parent action) with a well-developed set of auxillary hypotheses to test. But that test would not bear on the existence of some being somewhere in the universe that a human might call a "fairy" if he saw it. The same for the homeopathic example. Again, there are a plethora of auxillary hypotheses for the "action" of such nostrums compared to the action of pharmaceuticals. In the case of purpose, however, you have a hypothesis without any defined set of auxillary hypotheses up against only its negation, which is an infinite set.

Are all these people letting their philosophical positions influence their powers of scientific observations?

No, the people involved in UFOs, tooth fairies and homeopathy are doing (or can do) actual observations, while all you are doing in the case of purpose is making invalid inferences about the supposed lack of evidence when, in fact, no such observations, going to the issue of universal purpose, have been made.

No. My position is that I know science better then he does and it is not scientific to assume that the fine tuning argument has any scientific validity. It is not scientific to assume that examples of convergence lead to the conclusion of underlying purpose. It is not scientific to claim that the world knew we were coming.

Ah, so it is okay, on your personal authority, to rule out from scientific "evidence" of fine tuning (on some grounds or another) but it is also okay, on your personal authority, to rule that the lack of evidence for some amorphous idea you have of what purpose would look like counts as science?

And it is definitely not science to disguise ones philosophy under the banner of "evolutionary cosmology" implying that it has scientific validity.

Hmmm ... doesn't what he describes as "evolutionary cosmology" -- the notion that the universe as we see it is the result of its development under the constraints of natural law -- have scientific validity? And, given that he makes clear that he starts from that scientific notion but then extends his philosophy from it, isn't that better than someone who tries to rig the rules of science in his favor by fiat and proclaim his philosophy to be, instead, science?
 
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