11/14/2008

From the disunity of science to anti-realism

The two most popular arguments against scientific realism today are (1) underdetermination arguments and (2) the pessimistic induction. There is another kind of anti-realistic argument besides these two, which does not get the attention today that (1) and (2) receive. (Note: I would appreciate it if any readers could point me to someone working today who has developed anything akin to this third line of argument in detail.)

I don't yet have a clean formulation of this third kind of argument for anti-realism that I find satisfactory. All I have so far is an analogy. We see an instance of this third kind of anti-realist argument in Andreas Osiander's (much-maligned) Preface to Copernicus' On the Revolution of the Heavenly Spheres. Osiander argues that Ptolemy's astronomy is not intended to be the literal truth about the structure of the solar system on the grounds that, if the epicycles Ptolemy ascribed to Venus literally described Venus's movement, then Venus's apparent size for an Earthly observer should vary 16-fold. But Venus's apparent size does not vary in this way. Thus, even though Ptolemy's astronomy predicts planetary positions within the margin of observable error, if it were the literal truth it would also get apparent planetary size right as well.

What does this have to do with present-day scientific anti-realism? This is sketchy, but perhaps the increasing sympathy for 'the disunity of science' and the related notion of 'pluralism in science' could be used to argue for some sort of anti-realism. Now, what exactly those two expressions mean varies greatly from one person to another (I think; I would be happy for better-informed readers to enlighten me), but I think I can illustrate my point by imagining what a 16th Century pluralist/ 'disunifier' would say about Osiander's point above.

Such a person could say: Different scientific theories explain different phenomena. Ptolemy's theory only aims to account for apparent planetary positions, not their apparent sizes (and/or brightnesses). To demand that Ptolemy's theory also account for apparent sizes/ brightnesses is to impose an ideal of unified science upon Ptolemaic astronomy.

However, we today (and Osiander 450 years ago) think that this problem with apparent sizes is good evidence against the truth of Ptolemaic astronomy. That is, the 16th century pluralist/ disunifier seems to 'let a bad theory off the hook': we have evidence the theory is not true, but that evidence is discounted or ignored on the grounds that the theory's target domain of explanation does not include the countervailing evidence.

Now of course the question for modern-day antirealism is: how good is this analogy? In particular, is the kind of pluralism or disunity that people are championing (or at least accepting) today relevantly similar to the Ptolemaic pluralism/ disunity described above?

4 Comments:

At 1/1/09, Anonymous Anonymous said...

It seems to me that from the scientific point of view the issue is not so much whether the theory is true or not.The current standard physics model
cannot account for mass- a particle with mass (the Higgs Boson) has been posited and searched for. Shall then the current physics model be trashed because it cannot account for mass? NO, the theory is incomplete but not useless, and so it is with Ptolemaic Theory, which predicts eclipses accurately.
And just as the modern physics standard model will be added to, adjusted, to achieve what is perceived to be a greater descriptive accuracy, so too could the Ptolemaic.
NO one theory captures all phenomena--even in physics.
In place of the realism nominalism distinction (or real vs.unreal), physics and
indeed all of science substitute the observable. Whether and how something is observable then becomes the thorny question.
The truth of Ptolemaic theory is not the issue--the theory does predict--which is what science demands--rather the issue is the Ptolemaic Theory's incompleteness.

 
At 3/1/09, Blogger Greg said...

Thanks for stopping by!

Your point is well taken: looking back at my post, I realize that I wrote it through a very realist lens (by which I mean that the aim and standard of scientific hypotheses is truth period, not just truth about the observable part of the world).

However, I don't think the basic argument I discussed actually requires such realism -- I think it would work equally well if one thinks science aims at observational adequacy instead of truth. For we can say (instead of the first sentence of the penultimate paragraph in the original post): "this problem with apparent sizes IS good evidence against the *observational adequacy* of Ptolemaic astronomy." In other words, the Ptolemaic theory is in trouble regardless of whether you think of the aim of science as truth or observational accuracy.

Also, re: you Higgs Boson point, I don't think any theory should be rejected simply on the grounds that there is some phenomena it fails to predict/ explain (for then we would reject literally EVERY scientific theory); rather, my worry is that people will excuse bad predictions by appealing to pluralism.

Again, thanks for the comment; I really appreciate it.

 
At 18/4/09, Anonymous Ben said...

I think I can kind of see how pluralism/disunity can result in this third argument for anti-realism, especially when you said "Different scientific theories explain different phenomena" with regard to Ptolemy's accurate account of apparent planetary positions but not their sizes.

One can see how theories can then be parsed continually--perhaps ad infinitum--so as to preserve them on the grounds that it gets some micro-predictions correct while missing some others. So in the case of Ptolemy, an anti-realist could say that so long as this one part of his theory (his account of apparent motions) WORKS, it need not be falsified by the other part (his resultant account of planetary sizes) that does not work. So, the anti-realist would smugly have a way to show that we can preserve the parts of theories that work while discarding those parts that do not work, without having any of these parts needing to be true or false. And, this kind of preservation and discarding of parts of theories would be done under the justification of pluralism, in that, if we can allow many theories to explain many phenomena (e.g. wave mechanics, solid state physics, etc.) then why not allow many parts of working theories explain one phenomenon?

I would like to hear more about how this third argument for anti-realism can be cached out or whether it is an actual argument being worked on out there. Or, did you come up with it yourself?

 
At 21/4/09, Blogger Greg Frost-Arnold said...

Hi again, Ben --

I would also like to see how this argument is spelled out in more detail. I've seen it gestured at very briefly in a couple of places, but I have been unable to find a real discussion of it.

I can't say I came up with it myself, though, since I'm taking the basic idea from Osiander in 1543! I guess what I'd like to try to add is whether Osiander's general idea might actually be far more widely applicable to today's science, if science really is (as many folks want to say) disunified.

 

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