Wednesday, October 10, 2007

Christians and Scientific Realism

When I was in graduate school I took a very interesting seminar taught by James Van Cleve (who was on loan to Duke from Brown University at the time--now he's at USC) called "Realism and Anti-Realism". Virtually all of the readings were anti-realist in their orientation, and one of the students asked why the syllabus had such an anti-realist slant to it. Van Cleve answered "I just assumed that most people were probably already realists, and would be less familiar with the anti-realist literature." That turned out to be an accurate assessment, and the course was one of the most interesting I took at Duke principally because I found a great many of my own a priori metaphysical assumptions being challenged on every front.

That was fifteen years ago, at a time when many of my deeply held convictions were coming under heavy fire not only in my coursework, but from within my own conscience as well. In particular, I was struggling with the task of making sense out of my religious faith in the face of what Bas Van Fraassen has called "the scientific image" of man. As it happens, it was an encounter with Bas Van Fraassen's anti-realist philosophy of science that helped me through this rather difficult period. It occurred to me that a believing Christian (as opposed to the mind-numbingly banal "Christian" Owen Flanagan recommends being) could not possibly accept scientific realism, and Van Fraassen's work introduced me to a rather large body of literature that demonstrated that going anti-realist is a good idea for many other reasons as well.

We may define scientific realism in roughly this way: the task of science is to describe the operations of nature as they really are, on the assumption that representations of nature in the form of scientific hypotheses, formulae, theorems, etc., are literally true or false to the extent that they accurately representing nature. Anti-realism about science can take many forms, but the form that I defend is not particularly complex, it is merely the denial of this form of scientific realism. In particular, the anti-realism that I defend is simply the denial that scientific hypotheses, formulae, theorems, etc., can be literally true or false. Truth and falsity are, of course, rather important norms, but for the anti-realism that I defend a more important norm is usefulness.

To see what I mean, consider three different maps. Map (A) is a satellite photograph of the earth's surface such as you might find using Google Earth, only without any street overlays, place names, etc.: just the photograph of the ground. Map (B) is a road map of the sort you might purchase at the local gas station. Map (C) is a line drawing that I make to show you how to get from uptown Athens to my house. Now, in terms of "accuracy of representation" I think that it is arguable that there is a continuum here from "most accurate" to "least accurate", with map (A) being the "most accurate" to map (C) being the "least accurate". On a "realist" account of mapping, the satellite photograph will be the best, since it is the "truest" in the sense of being the most accurate representation of what's on the ground. But if you've ever used Google Earth to get somewhere without turning on the street overlays, you know that it's almost useless. You need to know street names, directions, distances, etc. So map (B) is far more useful than map (A). And if you have a specific sort of trip in mind, such as trying to get to my house from uptown Athens, then map (C) will be even more useful, since it has been designed to do precisely what you need to do, i.e., get yourself to my house from uptown Athens. So, which map do you want? Well, it sort of depends on what you want the map for. If, like me, you sort of enjoy looking at satellite photographs of the earth, I suppose map (A) will suit you, but most people want maps to get places, and so maps (B) and (C) are superior to map (A), even though they are less true in the sense of being less directly representational. They are, of course, representations, but they are not representations in the sense of being "literally true" in the realist's sense.

So the anti-realist favors usefulness over truth, but what could this mean in the domain of science? Isn't a scientific theory useful precisely to the extent that it's true? This is, in fact, a version of an argument that realists make all the time. They say that scientific realism must be true, because science is so successful. If science did not accurately represent reality, they say, there would be no way for science to be as successful as it is, because the only way for science to be successful is for it to "get things right" about the external world. Hence, to the extent that "science works", it is also literally true.

Now, it seems to me that even a moron could see that this is a circular argument, and yet realists make it all the time. Indeed, it seems as though the anti-realist would have a perfectly simple rejoinder to this kind of argument: if scientific realism is true, then the history of science along with the hypothetico-deductive model of theory formation teach us that all of our scientific theories are always false, regardless of how useful we may find them to be at one time or another. I don't actually want to get into that particular problem, though, because for the Christian that whole issue is academic. Scientific realism also presupposes both global materialism and global empiricism, and the Christian must reject both. Global materialism is false for the Christian because the Christian believes that there is at least one non-material being, namely God. Global empiricism is false because the Christian believes that it is possible to have knowledge of a non-perceptible entity, namely God. Christians, of course, can be scientists, since they may quite easily adopt both local materialism and local empiricism (that is, materialism and empiricism when doing science) without violating the principles of their Christian belief.

So the Christian is interested only in scientific theories that are useful, and is not interested in whether or not they are true (mostly they will have to be regarded as false for one reason or another anyway, so why even get into that whole problem?). Consider the difference between the heliocentric and the geocentric models of the solar system. Both of them have been "useful" at one time or another, though at present we believe that one of them is false. Some would like to believe that the other one is true, but of course that presupposes that because the other one works better that it is also truer. It may turn out to be the case that the heliocentric model will need to be modified as more data are collected, thus showing the present version of it to be false. This is perhaps unlikely, but a genuine scientist cannot rule out the possibility that his present hypothesis is false, otherwise science could never move forward, it could never take into account new data. Rather than say, "this model is false" the Christian says "whether or not this theory is true or false, it's the one that I can use right now to make these predictions or to accomplish these goals." One of the things that led to the abandonment of the geocentric model in favor of the heliocentric was precisely this: one model was more useful than the other. It's not that there were new data available--there weren't. Both models can make a certain amount of sense of the observational data. What's more important than that is that the heliocentric model enables us to do more given the other theories that we also accept. Hence the criterion is not truth (since on that criterion we could never finally accept any theory), but usefulness.

Looking at science in this way enables the Christian to accept a theory like evolution even when many defenders of evolution claim that accepting it means rejecting religious belief. That would only be the case if two conditions were met: (a) evolutionary theory logically excludes the truth of any religion and (b) scientific realism is true. Since both (a) and (b) are false, and since evolutionary theory is very useful in explaining the origins and development of life, the Christian not only can but ought to accept evolutionary theory.


John Farrell said...

I think you once mentioned there was a more positive sounding label to the anti-realist position. I find myself chafing at the idea of adopting an 'anti' label.


If I had one quibble:

One of the things that led to the abandonment of the geocentric model in favor of the heliocentric was precisely this: one model was more useful than the other. It's not that there were new data available--there weren't. Both models can make a certain amount of sense of the observational data.

I would only add that the other main reason for adopting the heliocentric appoach--or any modern theory-- was that it made do with fewer assumptions than the geocentric (meaning, it required fewer epicycles to match the data).

But this doesn't change your main point, which I agree with entirely. Excellent post.

Shane said...

How does this:

"We may define scientific realism in roughly this way: the task of science is to describe the operations of nature as they really are, on the assumption that representations of nature in the form of scientific hypotheses, formulae, theorems, etc., are literally true or false to the extent that they accurately representing nature."

imply this:

"Scientific realism also presupposes both global materialism and global empiricism, and the Christian must reject both."

I don't see any reason that commitment to scientific realism implies a commitment to global materialism.


"One of the things that led to the abandonment of the geocentric model in favor of the heliocentric was precisely this: one model was more useful than the other. It's not that there were new data available--there weren't."

I know it is just an example, but it is a wrong example. The invention of telescope led to Galileo's observing the phases of Venus, which you can't explain on the ptolemaic astronomy.

More importantly, I think the geocentric/heliocentric example furnishes an important counterexample to your point.

Let's suppose it were the case that for the calculation of the calendar that geocentric astronomy and heliocentric astronomy were precisely as useful as one another. (This isn't really the case, of course, but let's assume.)

Now, geocentric astronomy implies the sun is the center of the universe and heliocentric astronomy implies that the sun is not at the center of the universe. Now it is clear that at least one of these views is false because the sun cannot both be the center of the universe and not be the center of the universe at the same time by the law of the excluded middle.

At this point I think your only option is to claim that science just doesn't produce real propositions (i.e. statements with truth-values), which seems to reduce the statements scientists produce to something like poetry or emotivist judgments like, "Neutrons, yuck!"

I don't find that a very appealing conclusion.

Paul Hamilton said...


If geocentricism is false, does that make heliocentric theory necessarily true and immune from modification in principle?

As a matter of fact, the phases of Venus did not resolve the debate, even if Galileo thought they did. Tycho Brahe's theory accounts for Venus' phase shifts while maintaining geocentricism, even if Ptolemy's geocentricism could not. I think we have enough evidence today to refute Brahe's general theory, but Galileo didn't have that evidence at the time. So no, Venus' phase shifts did not refute geocentrism, and to this day it does not "prove" heliocentricism true, as any loyal advocate of the hypothetico-deductive method would tell you.

I think you may have missed some very important parts of Dr. Carson's argument. My general rule of thumb is that if my reading of a professional philosopher's work commits them to making a sophomoric mistake (such as a denial of the LEM), the problem is most likely in my interpretation, not in the work itself.

Dr. Carson, aside from this Van Frassen guy, do you recommend any other authors/books which I can add to my reading list?

Scott Carson said...


Van Fraassen is a great place to start, and if you're looking for something a little more on the overviewish side, there is a great introduction to the philosophy of science by Peter Godfrey-Smith of Stanford called Theory and Reality: An Introduction to the Philosophy of Science. He defends a version of realism, actually, but it's not s simplistic, straightforward realism and it's fairly interesting.

Other recommendations might depend a little on what sort of science you're principally interested in. Robert Brandon and Elliot Sober are both very good on the philosophy of biology and have each written very good mid-level books on the topic as well as some more advanced stuff. For philosophy of physics you can't beat folks like Arthur Fine (of "natural ontological attitude" fame), Abner Shimony, and R. I. G. Hughes (Hughes in particular has written a very good introduction to the philosophy of quantum mechanics that I highly recommend). For the philosophy of the social sciences I recommend Philip and Patricia Kitcher, and for philosophy of mind/neuroscience I recommend Paul Churchland.

If what you're particularly looking for is philosophy of science written by believers, that's a little harder to come by and Van Fraassen is something of an outlier. But That's not to say that they're not out there. Lynn Joy and Ernan McMullin, both of Notre Dame, are believers who work in philosophy of science, for example, and McMullin, though he's retired now, has done some very important work that is widely regarded.

I can probably think of some more specific titles if you can give me an idea of what you're looking for in particular.

Tom said...

Reminds me of the time back in '98 when I heard a Dominican priest give a talk on science titled, "What's useful but not true?"

I came away thinking the poor old fellow just didn't get it. (Well, I mean, why would he, he'd only been teaching Thomistic philosophy at the graduate level for forty or fifty years.) Particularly silly, I thought, was him saying something like, "They say you can use this numerical method to compute the answer to as many digits as you want. Well, I want all of them! I want to know what the answer is."

It took me some time to realize that I'd been thinking "true," in a scientific context, means "true enough," without ever really noticing that "true enough" implies "not true."

Speaking of Dominicans, does William A. Wallace, O.P., ever show up on philosophy of science reading lists?

Scott Carson said...


Yes, indeed, when I was in graduate school his books on Galileo were a particularly hot discussion topic.

He's also done some nice work on St. Albert the Great.

I haven't actually read his 1979 book, From a Realist Point of View, but I suspect the title suggests that he may not agree with me about anti-realism! (There are varieties of realism, however, that come rather close to anti-realism sometimes; one has in mind Simon Blackburn's so-called "quasi-realism", Hilary Putnam's "internal realism", or even Grover Maxwell's epistemological realism.)

Shane said...

@ Paul

"If geocentricism is false, does that make heliocentric theory necessarily true and immune from modification in principle? "

Of course not. I wonder why you would think so, since I did not claim it did.

Paul Hamilton said...


I didn't say you did. I was drawing attention to the point that Dr. Carson was making in his post. That's a long way from reducing scientific propositions to emotive judgements.

Dr. Carson, as I said earlier I was somewhat unhappy with my philosophy of science course. Since the course wasn't great, I only have a vague idea of what I'm looking for. I think the titles you gave me are good for now. Now I just have to hope that CUA's wretchedly bad library actually holds any of these books. ;-)

gatesofsplendor said...

I have a lot of questions about anti-realism, science, and their relation to theology. I am currently finishing up Van Fraassen's "The Empirical Stance" and find it to be a very interesting read.

I just found your blog today while looking for discussions on anti-realism, so forgive me if I am going over ground that has been covered previously.

I have perused your posts on evolutionary theory and theology, and find much of what you say interesting. However, you also raise many questions for me. I guess I thought I was beginning to understand what anti-realism is, but now I am not so sure.

Questions: 1)If scientific theories are neither "true nor false", then how do you, in other posts speak of it as if EvoTheory is true?

If I need to draw quotes I will, but I see some statements of certainty, which would seem to go against an anti-realist view (pragmatist view?) of scientific "advance".

2) In what sense is evolutionary theory "true"?

3) In its ability to make predictions?

4) Does the ability to make predictions make a theory true?

5) How can one judge a group like creationists to be crazy?

They of course view scripture as an authority that transcends a discipline such as science, which does not give certain knowledge (or does it?). From what I have read some of them also take an anti-realist view of science.

What am I missing?

6)How do we "know" that EvoTheory will not be totally over thrown by a new theory that may seem just as absurd as creationism or intelligent design? Van Fraassen notes that scientific theories that are posterior to a theory are always viewed with suspicion,

7) If 6 true, then how will we know when evolutionary theory has run its course, since we will probably view the competitor with suspicion?

I look forward to your answers. I am trying to work these things out.

Just an uneducated layman,
Blake Reas

Scott Carson said...


Those are good questions. Here are some suggestions.

(1) I don't believe that I ever said that ET is "true"--if I did, it was a misstatement. It is, perhaps, as good as true, by which I mean only that it is very robustly confirmed (in the empirical sense in which scientific theories are tested). So far as I can see, there is no reason to regard any scientific theory as literally "true". If we were to regard a theory as literally "true" then there would be no reason to test it or modify it, but it seems to me that science presupposes that all theories are open to revision pending new discoveries. That is, we must always be open to the possibility that better theories exist. Does the existence of a better theory mean that the current theory is "false"? No, only that it is less useful or, indeed, perhaps completely useless. If you want to use the word "false" to mean useless, that's OK by me, but doing so is a kind of anti-realism.

(2) I'm hoping (1) answers (2): ET is "true" in the sense that it is robustly consistent with empirical testing, it can usefully be used to make predictions, and it is more satisfying, for a variety of reasons, than any competing theory about the origins of life and the diversity of species. If it were literally "true"--or even if we just believed it to be true--we would have no warrant for testing it, so I don't see that we have any excuse for regarding it as "true" in a realist sense. Again, I don't believe that I ever said that I myself think of ET as being true in a realist sense, but if I did it was a misstatement on my part.

(3) The ability to make predictions doesn't make it true, but useful. It may also be true in a limited way, but a Christian is committed to the view that blind physical forces are necessarily only part of the explanatory picture. Science is by definition limited to the empirical and the material, so it can never give a complete explanation of What Is as far as the Christian is concerned. The scientist need not commit himself to Christian beliefs, of course, so pagan scientists are at greater liberty to entertain the possibility of a strong, global scientific realism. I don't think they ought to accept it even if they are atheists, because I don't think realism is a very good scientific attitude, but I do know plenty of very smart scientific realists, and in fact I know some Christians who are scientific realists. To each his own, I guess.

(4) No--not even for the realist. The geocentric model of the solar system was certainly able to make certain kinds of predictions, and with enough ad hoc modifications it could have made predictions as accurately as the heliocentric model.

(5) Just by listening to them talk.

But seriously folks, their view of Scripture is heretical to begin with, so even the Christian is not bound to take them seriously. If their own community rejects them, there's certainly no reason for the scientific community to take them seriously.

(6) We don't know what future scientific theories will be like with any certainty, but it does seem as though there are certain constraints on what future scientific theories will look like. For example, they won't appeal to the non-testable, as ID does. But I agree with Van Fraassen that revolutionary scientific hypotheses will be viewed with suspicion, regardless of how useful they are. And one has only to consider Einstein's skepticism about quantum mechanics to realize that there is nothing out of the ordinary in this situation.

(7) Possibly ET will never "run its course". I don't think that it is a necessary feature of scientific theories that they become obsolete, it is merely a matter of historical contingency that all of them have so far, with the exception of the one's we currently subscribe to. Many of our current theories may also become obsolete, but that is certainly not necessary: it is at least possible that some of them will continue to be useful in one sense or another for as long as humans are interested in testing things. I suspect that Newtonian mechanics may very well fall into this category, even though we know that Newtonian mechanics are not actually true in a global sense. Since we don't ordinarily interact with subatomic particles in our day-to-day lives, Newtonian mechanics are good enough for making sure we don't fall off of cliffs or bump into walls. Perhaps the anti-realist may be permitted to say that Newtonian mechanics are "as good as true", or "true enough", at least for certain purposes.


gatesofsplendor said...

Dr. Carson,

Thank you very much for your explanations.Your answers cleared up many of the questions that I have been having concerning anti-realism and theology. If I misunderstood some of your past posts I am truly sorry.

Blake Reas

gatesofsplendor said...

I had one more question concerning anti-realism, that came to me this morning while having my morning coffee.

If a theory does not have a truth value, then does it warrant that we believe it in some way? In other words, are we shirking our epistemic duties in some sense if we do not believe in whatever theory holds sway?

Blake Reas