Friday, May 4, 2012

Realism vs. Anti-Realism 2: Arguments Concerning Scientific Realism by Bas Van Fraassen

Notes and Thoughts on Arguments Concerning Scientific Realism

Summarizing quote: "The rigour of science requires that we distinguish well the undraped figure of nature itself from the gay-coloured (heh!heh!he said "gay") vesture with which we clothe it at our pleasure."
--Heinrich Hertz quoted by Ludwig Boltzmann, in turn quoted by Van Fraassen, in turn quoted by me.

In the previous post, I introduced the realist-antirealist debate in philosophy of science.  Again, although there are many species of each, we can loosely say that the debate is over whether unobservable theoretical entities, like subatomic particles, refer to something real or are purely theoretical and we should not think of them as corresponding to some real "thing".

Historically, logical positivism was the first contemporary position in philosophy of science (the only statements that have meaning are verifiable and refer to objects we can directly perceive).  Scientific realism mainly grew out of criticism of this anti-realist position.  In this article, van Fraassen agrees with realists that we ought to reject the positivist philosophy, but disagrees that this should entail realism.  Instead, he proposes an anti-realism that he calls "constructive empiricism".  The idea is that we can accept scientific theories but remain agnostic about their truth; we require only that they be "empirically adequate" (i.e., true about observables). 

Scientific Realism and Constructive Empiricism

Scientific Realism: Vas ist das?  An unsophisticated definition is that the picture of the world that science gives us is a true one, "faithful in its details, and the entities postulated in science really exist: the advances in science are discoveries, not inventions."  There are a couple of caveats.  Scientific realists aren't necessarily committed to the view that all current scientific theories are True or that the scientific enterprise is going to finish any time soon.  But this is the gist of it.  A philosophical theory about science must answer two questions: what is a scientific theory, and what does a scientific theory do.  Realists say scientific theories are about what there really is, and science is an activity of discovery not invention.

Summarizing statement of scientific realism:  "I understand scientific realism to be the view that the theoretical statements of science are, or purport to be, true generalized descriptions of reality." (Ellis)

The advantage of this statement is that it avoids any commitment to a particular current theory being true, only that they "purport" to be.

Another formulation:  A realist (with respect to a given theory  or discourse) holds that (1) the sentences of that theory are true of false; and (2) that what makes them true or false is something external--that is to say, it is not (in general) our sense date, actual or potential, or the structure of our minds, or our language, etc...(Dummett and Putnam)

Yet another formulation:  That terms in mature scientific theories typically refer, that the theories accepted in a mature science are typically approximately true, that the same term can refer to the same thing even when it occurs in different theories--these statements are viewed by the scientific realist. . . as part of any adequate scientific description of science and its relations to its objects. (Boyd)

Final formulation:  Science aims to give us, in its theories, a literally true story of what the world is like; and acceptance of a scientific theory involves the belief that it is true. (van Fraassen's summary of all the views)

8 Quick Arguments against Realism, How it Can't Explain the Success of Science, and NKTB
In these arguments I will primarily be referring to scientific theories about  (directly) unobservable theoretical entities like atoms and subatomic particles.

Step 1.  We can have lots of fun!  Just because a theory's central terms (e.g. subatomic particles) refer to something doesn't entail that the reference will be successful.  For example, if you see the shadow of a bunny rabbit on the wall you might infer there's a bunny.  But the shadow might have been made by someone's fingers you can't see.  So, your belief that "there's a bunny" doesn't refer to the entity to which you think it does.   

Also, just because a theory is successful, doesn't mean that all or most of its central terms (entities) refer to something.  For example, in early chemistry heat was thought to be some sort of invisible fluid "phlogiston".  But it turns out that term doesn't refer to anything real.  Same goes for "ether" that was postulated to explain how light travels.  Given historical precedent, there's no reason to suppose our theories are any better off. 

Step 2.  I can 'splain it to you! The notion of "approximate truth" is too vague to permit us to judge whether a theory comprised of laws that are all approximately true would be empirically successful; that is, would it adequately describe the observed phenomena.  It seems that a theory can be empirically successful even if it is not approximately true.  Take for example Newtonian physics.  It gets the predictions right (at low relative speeds) but its theoretical explanations of time and space are not approximately true.

Step 3.  Read it with me! Related to the previous point is that realists don't have an explanation of how some past theories had theoretical terms that turned out not to refer to anything (eg. phlogiston, ether) yet were successful predictors of empirical phenomena.  That is, the theory worked (for the known phenomena and testing methods) yet it was totally wrong.  There was no phlogiston or ether.   Who's to say the same won't happen with today's theories? 

Step 4.  Tell me some more!  Realists who give a convergentist (science converges on the truth by building on previous theories) account of scientific progress can't give a good explanation of how this works.  The realist model is that the new better theory preserves some of the laws that were in its predecessor because they were approximately true.  But, obviously they weren't approximately true enough to get it right, otherwise why would the theory have been revised and replaced?  So, what does "approximately true" mean if something that we say is approximately true has to be modified?  Where's the line between a modification, a change, and a new law?  "Approximate truth" is too vague to mean anything.  How did the preceding theory's law refer to something approximately true about the world if it was getting it wrong?

Step 5.  Bees in a hive!  Realism presupposes its truth (Problem of circularity).  Realism assumes that just because a referring theory or an approximately true theory are explanatorily successful that they are true.  But this presupposes that explanatory success and truth are one and the same, but they aren't.  History is full of examples of theories that were explanatorily successful, yet false.

Step 6.  Reeeee mix! (wika wika).  Just cuz a theory does a better explanatory job than its predecessor, this doesn't imply that the new theory can explain why the others succeeded or failed.  For example, Einsteinian physics doesn't explain why Newtonian physics was approximately true.  So, this idea of convergence on truth is weakened.  In other words, if E physics can't explain why N physics got it approximately true, how can we say that N physics did get it approximately true or the E physics was built on N physics?  It might have gotten its predictions right for all the wrong reasons.  Nukin' pu nub fo all the wong weasons...

Step 7.  I know a guy named Devon.  He built his own convenience store.  He calls it "Devon-eleven".  Again, against the convergent view of science:  If a new theory's predecessor has been falsified then it is not possible for the new theory to contain either all of the predecessor's content or all of its confirmed consequences or all of its theoretical mechanisms.  The realist might reply that this is not a necessary condition on a new theory.  But the anti-realist counter is that if the realist believes scientific theories aim at referring to real things and are approximately true then he has to admit that the previous theory didn't do this if some of the postulated entities or laws have to be rejected.  And again, why assume that the new one gets it right?

Step 8.  Isn't this great?  Realists haven't given any argument for why anti-realists won't be able to explain the the success of science.  The only "argument" the realists make against antirealists is that otherwise it would be a gosh-darned miracle that our theories--which have allowed so much prediction, explanation, and beneficial application--didn't refer to real things in the world.  But that's not an argument, that's the fallacy of personal incredulity. 

The conclusion is that realism has not shown how it explains scientific success beyond presupposing that explanation=truth.  Throughout the history of science there have been many scientific laws that approximately explained all or most phenomena at the time, but were later shewn to be false.  Realism cannot explain their success.  On their model, those theories and the entities which they postulated were approximately true of the world.  But as we've seen they weren't.  Realism is the wrong model for interpreting what science does and what theoretical entities are (they are not approximate references to real things in the world).

On the other hand, we shouldn't go too far in the other direction.  We shouldn't say that a theories predictive and explanatory power are meaningless.  The difference might be between wanting to believe something is true and having good reasons for believing it.  That sounds right.  But I'm not clear on what other possible reasons beyond predictive and explanatory power there might be.


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  2. I really like your article, and it very well describes this viewpoint, but honestly, the informal remark in the first paragraph ruins the tone of the paper. Its unprofessional, and destroys the credibility of the source.

  3. Thank you for your feedback Chris. I can see how that might be a problem. I'll consider editing it but not sure yet because part of the tone of the blog is to be informal and sometimes a little silly. Maybe because it's difficult to convey my exact tone in the opening paragraph, it could come across wrong. I was intending to parody Bevis and Butthead as if they were reading the quote.

    1. keep the informal tone! enough of the seriousness! philosophy for the non-philosophers, people like me, not for the bearded men behind the desks!
      Anyway, I guess if one day you'd want to write something formal then you'd write a book or something, right? This blog is great like it is!

  4. Replies
    1. You just made me feel old:

  5. Thank you for your article, it was of great help in the assignment

    1. You're welcome! Thanks for letting me know.