Thursday, May 3, 2012

Realism vs Anti-Realism: Ontological Status of Theoretical Entities by Maxwell

Notes and Thoughts on "The Ontological Status of Theoretical Entities" by Grover Maxwell

One of the big debates in philosophy of science is between realists and anti-realist.  Although there are many types of each, generally speaking we can say that realists think that our theories describe real entities while the anti-realist don't.   Here's an example to illustrate.  Consider "electrons".  When I use this word does it refer to an actual physical thing?  Or it it referring to a theoretical account of a set of observations? Or is it just a "useful fiction" to facilitate scientists' thinking but should not be thought of corresponding to any real physical entity?

A problem is that in modern science no one has ever directly observed any of atomic or subatomic particles, although we talk about them as though they're real physical things.  Consequently, our knowledge of them is only inferred from bleeps and blips on instrument panels.  "Electrons" and such are merely theoretical postulates to give a coherent account of the bleeps and blips that we count as observations.  So, the anti-realist argument goes, all these theoretical entities (atoms, subatomic particles, forces) are just that, they're theoretical, not real entities.

Maxwell's essay is a response to several anti-realist positions.  His basic argument is that the divide between observable and unobservable entities which anti-realists rely on is itself only a theoretical distinction. For example, before microscopes, germs were theoretical entities.  But with the invention of microscopes they became observable.  So, why should we suppose that just because some entities are unobservable now that they will continue to be.  Therefore, they can't depend on the unobservable/observable distinction to support their theoretical/real distinction.

Quick Definition:  "Ontological Status" is a fancy way of talking about the degree to which something exists.  For some people, the only things that have ontological status are physical things, for others ontology extends to concepts like numbers and (maybe) ideas and mental states.  There are a great many views on what sorts of things exist.  But (almost) all agree that physical things exist; that is, they have ontological status.

The Observable-Theoretical Dichotomy:  R U 4 Realz?

Vs What we see through a microscope isn't real: 
 I know this will sound kinda wack to the peeps out there who haven't studied philosophy.  But wackiness abounds in philosophy.  Lets carry on shall we?

Suppose, pre-microscopes, a scientist infers the existence of germs.  His theory appeals to unobservable "bugs" that cause infections.  Application of his theory yields great results when people start washing their hands and such, lending further support to the theory.  A few years later the microscope is invented and he's vindicated--these "bugs" are observed and given the name "microbes".

A philosopher of science, upon hearing this, denies that the microbes were ever observed under the microscope.  But why?  He argues that "when I look through a microscope, all I see is a patch of colour which creeps through the field like a shadow over a wall.  And a shadow, though real, is certainly not a physical thing."  Basically, when you look through a microscope you are not directly seeing the thing in the plate, rather you are seeing the light which bounces off the microbe which is then amplified (i.e., distorted), then you see the distorted light coming out of the lens.

What's the basic argument?  It's that the microscope distorts/amplifies the light which reflects off of the microbe, so we're not really seeing the microbe, but a distortion.  But there seems to be some arbitrariness going on.  If I look through a slightly convex window does that mean that I can't infer that what's on the other side isn't real (i.e. physical)?  What about people who wear glasses?  Are they not allowed to infer that what they're seeing is real just because the lens distorts the light?  That seems kinda wack.

Of course this is not to say that we can't draw any line.  Certainly there's a difference between inferring the physical reality of a room through a pair of glasses and inferring the Higgs-Bozon particle from the instrument panel and computers at CERN.  What are the implications to our ontology?  Do we ascribe different ontological status to things depending upon how they were observed?  Why should how they are observed affect whether they're 4 realz?

There is also the problem of people and organisms having different natural levels of resolution in their visual faculty.  Is the world less real to the coke-bottle-glasses-wearing person than it is for me with my 20/20 vision because I can see at a higher resolution?  That seems wack.  When someone gets lasik, does the world become more real for them?  There's certainly a silliness to this distinction which points to its arbitrariness. 

There's another problem about the continuum of existence.  Is an very small molecule, only visible under an electron microscope less real than a larger molecule visible under an optical microscope?  What about some salts and polymers that can have single molecules so large that they are visible to the naked eye?  Does each one have a different level of reality?

Vs Only Entities that Are in Principle Observable Are For Realz
So, this is the view that only entities that are in principle observable can be considered real.   Conversely, if an entity isn't in principle observable then it remains only a theoretical rather than real entity.  So on this view we will appeal to facts like the physiology of the eye and the properties of the postulated theoretical entities.  The "in principle" part also refers to the fact that some theories entail that the entities to which they refer are about are unobservable.

Here Maxwell makes what I think is a poor argument.  He suggests a thought experiment whereby some drug makes it possible for us to directly perceive electrons (which are theoretical entities). The mechanism is that the drug alters our perceptual apparatus such that we can perceive the electrons with some latent sense faculty--not necessarily visually.   I don't even understand what it would mean to perceive an electron with some sense beyond the ones I have.  Maybe my imagination isn't good enough.

Then he sort of dismisses this example, probably because er'body's gonna think the same thing that I did, and proposes another.  Suppose a mutant is born who is able to "observe" ultraviolet radiation, or even X-rays, in the same way we observe visible light.  But this counterexample (I don't think) does the work he needs of it.  I don't think anyone is saying that X-rays and ultraviolet radiation are in principle unobservable; in fact we know several animals and insects "perceive" ultra-violet light.  

I think there's a difference between trying to observe subatomic theoretical particles (i.e., entities) and parts of the spectrum.  I'm just not sure what it is...Maybe it's that there's a difference between the ontology of parts of the spectrum and the postulated ontology of particles.  What's the ontological status of light?  I'm totally confused by this.  When we say "that gives off red light" do we mean there's something floating through the air that causes the appearance of redness?  I don't think so.  We mean (scientifically) that the surface of the object in question absorbs all wavelength of light except the one we perceive--but there's still no red thing floating into my eye.  But when we talk about subatomic particles, we're implying reference to a physical-ish thing.  I don't know.  There's some kind of difference there.

Maybe that is it.  When we observe light, we don't give it ontological status of a physical thing, but with sub-atomic particles we do.  So, why does that matter?  I guess because his thought experiment is all about showing that the difference between things that are observable "in principle" and things that are mere theoretical entities is an illusion.  I'm gonna disagree for now.

Next, he says the matter at hand is not to speculate which theoretical entities are or aren't in principle observable.  It is the theory within which the theoretical entity is postulated that stipulates this.  So, in a  way saying "un/observable in principle" is superfluous because this fact is part of the theory.  This is the heart of the matter because it seems there is no pre-theoretical way to determine what is or isn't observable.  It's like this y'all:  peeps were rappin' 'bout 'lectrons 'til there was a theory that postulated them.  That theory wasn't someone's wacky dream, it was based on a crap-load of observations.  So, as far as theoretical entities go, it is the theory itself that defines whether the entity is observable or not.  And that's kinda cheating.  

I want to rejectify this a little.  It's true that theoretical entities like subatomic particles have their un/observability quality stipulated by that same theory.  But, that theory operates within a larger theoretical framework whose principles are that objects below a certain size are unobservable for reasons x, y, z.  Theories don't exist in isolation, and they don't emerge independent from meta and pre-theoretical contexts; these other considerations shape and constrain what types of new theories and hence new theoretical entities are possible.  So, it's not entirely circular.

Of course, Maxwell can reply that it still is circular because the parallel and meta-theoretical considerations are already defining what types of entities are in principle observable.  That maybe so, but any theory of observation, including that there are real macro physical objects instead me being plugged into the matrix, requires some pre-theoretical stipulations about what is un/observable.  That we have background theories doesn't make it a free-for-all that anything in principle observable.  At most, Maxwell can say that we should be agnostic about what types of theoretical entities are un/observable. 

He can also reemphasize the point that an entities observability has no necessary logical bearing on its existence.  That seems right.  But, (I repeating myself) it cuts both ways: an entities' unobservabilitization doesn't make it's existence any more likely either.  If anything it's a strike against it, albeit a small one.  Maybe unobservable.

Vs.  Observation Language
Background:  So, in philosophy one way we distinguish between different kinds of sentences is between observation sentences/language and theory sentences/language.  Observation language refers to statements about our observations.  Eg. "there is a red spot on the wall", or "the gauge moved from left to right", or "the cat weighs 8kg".  There are various limits on what can be included in an observation language, for the sake of argument Maxwell address a general one that allows physical object terms (chair, table) and observable predicates (big, brown, heavy, etc...).  

The main point is that all descriptive terms refer to the thing that has been observed or are reducible to something physical.  Any term in my observational language has to reference some real thing.  So, on a strict version of this, if I have never actually observed x, then the term is not observational language for me because it doesn't refer to anything I've observed.  For example, I've never seen a liger, so in an extremely restrictive observational language "liger" wouldn't be an observational term for me.  Of course this strict of a language is kind of silly.  Just because I haven't seen a liger myself shouldn't have any bearing on its ontological status.  

So, we might loosen our observational language and say that observational terms must be members of a kind, some of whose members have been observed or instances of a property some of whose instances have been observed.  In this case, I can use 'liger' because it's a kind of cat, and I've seen cats before!  Or maybe we can say that ligers have properties that I'm familiar with, so for that reason I can use 'liger' in my observational language because it refers to sets of properties that I've observed.  The main point is that our observational terms have to refer to something real.

But this formulation also runs afoul.  Sometimes an entity can be one of a kind.  Or sometimes our language is clearly observational, yet doesn't refer to anything; eg. ligers over 14' long.  There is no instance of property or kind of 'Ligers over 14'' long that could be the referent of the expression.  The way out is to make our properties more general.  We can say, well, we are familiar with cats, with the colour blue, and with things that are 14' long, so our language does reduce to properties and kinds.  

The problem is that once we loosen the restrictions this much on observational language, it's hard to see how we're going to distinguish between theoretical and observational entities.  For example, in this loose language I can say that unicorns are part of my observational language because unicorns have properties that I'm familiar with.  The same goes for sub-atomic particles--they're going to have general properties that we've experienced in real entities.  Eg. spin, velocity, mass.   So, once I've allowed properties and kinds to be very general in my observation language, on what grounds can I distinguish theoretical entities from observable ones?

What Do?
Clearly, it's important to have some kind of distinction betwixt observational and theoretical language.  We need observation sentences to either confirm theories or to refer to entities that are currently unobservable.  If there is no distinction then er'thing's just cirkalur.   So, what do?  Maxwell says that instead of basing our observations in terms that must be cashed out in physical kinds or properties, we ought to use as our base the "quickly decidable sentence".  K.  Just a little forewarning.  Shit's about to get a little loco.  Don't worry about it too much.  Keep going.  Dju cang do eet!

A quickly decidable sentence is "a singular, non-analytic sentence such that a reliable, reasonably sophisticated language user can very quickly decide whether to assert it or deny it when he is reporting on an occurrent situation."  Say wut?  Non-analytic means that the predicate isn't contained in the subject (i.e., as opposed to analytic like "a bachelor is an unmarried man").  As for the rest, I'm guessing he just means that the descriptive terms aren't too mumbo-jumboish and that so long as a person isn't a complete rube they'll be able to say of the observation that the descriptor applies or it doesn't.  

For example, if someone axes me "Do you wanna do karate in the garage?"  That's a quickly decidable sentence.  Or suppose I put on a lab coat on and do a titration in a beaker being warmed by the bunsen burner.  I have test tubes too, but they're just for effect.  Anyway, a quickly decidable sentence would be something like "the solution is a base because it turned purple and I'm wearing a lab coat".  I could quickly assent to that.  I'll be honest, I'm not too sure if this is exactly what he means.  I'll have to do a bit of research.  

Lets add one more thing to muddle our minds.  An observation term will be defined as "a descriptive term which may occur in a quickly decidable sentence".  Ok, so that kind of works with what I just said about the contents of the quickly decidable sentences not being full of mumbo-jumbo descriptors; just simple stuff like, it's purple, it's a base, etc...

We have two pieces that fit together--quickly decidable sentences and observation terms--to give us a new, non-reference based version of the observation sentence.   So, an observation sentence is a quickly decidable sentence whose only descriptive terms are observation terms.  Eg. Is that apple crunchy?  Yup.   Or "that Delorian requires 1.21 jigga watts"  Assent or dissent?  Assent in no time!

One more example.  Suppose you're driving down the freeway and you see someone mowing their lawn.  You could probably assent that they were mowing the lawn, but maybe not what colour his shirt was or the square footage of the lawn.  So, "he was mowing the lawn" would be a quickly decidable observation sentence while, "he was wearing a navy shirt with brown pants" wouldn't be.  Perhaps if you were walking by and could make more careful observations "he was wearing a navy shirt..." would become a quickly decidable sentence.  I'm not sure what Maxwell would say.

I have a problem with this.  He proposes this new theory of observational sentences but doesn't really tell us under what conditions they apply.  The closest he comes is acknowledging that determining how quickly we can evaluate the truth or falsity of an observation sentence is unknown so far.  Well, so how the crap do I know what qualifies as a legitimate observation that I can evaluate and what doesn't?  It's a totally useless criteria without this information.  It's like saying, "you're right when you're right".  Thanks, but how do I know when I'm right?

What was the whole point of this ruckus?  Maxwell is a realist arguing against the anti-realists who say that non-observable entities like sub-atomic particles are merely theoretical and don't exist in any real way.  The anti-realists say that atomic and subatomic particles are only theoretical entities constructed to explain indirect observations.  Maxwell's argument is that the anti-realist assumptions that the observable-unobservable line is objective and that it bears on the observable-theoretical line are false.  He showed that the line between observable and unobservable is contingent and a function of our physiology, current state of knowledge and the instruments we happen to have available.  Because where the line between observable and unobservable objects is drawn is arbitrary, it is of no relevance to an entities ontological status.  To summarize in a sentence: jus' cuz we can't see wiph our eyes don't mean it ain't fur realz.


  1. Dude this was great

  2. 'Dju cang do eet!' Yes, I can! Thanks a lot. Going to ace this observables/unobservables essay now! :)