Scientific Realism and Constructive Empiricism

 

Berkeley's razor

 

Berkeley's razor is a rule of reasoning proposed by the philosopher Karl Popper in his study of Berkeley's key scientific work De Motu.[10] Berkeley's razor is considered by Popper to be similar to Ockham's razor but "more powerful". It represents an extreme, empiricist view of scientific observation that states that the scientific method provides us with no true insight into the nature of the world. Rather, the scientific method gives us a variety of partial explanations about regularities that hold in the world and that are gained through experiment. The nature of the world, according to Berkeley, is only approached through proper metaphysical speculation and reasoning.[1] Popper summarizes Berkeley's razor as such:

 

A general practical result—which I propose to call "Berkeley's razor"—of [Berkeley's] analysis of physics allows us a priori to eliminate from physical science all essentialist explanations. If they have a mathematical and predictive content they may be admitted qua mathematical hypotheses (while their essentialist interpretation is eliminated). If not they may be ruled out altogether. This razor is sharper than Ockham's: all entities are ruled out except those which are perceived.[2]

 

In another essay of the same book[3] titled "Three Views Concerning Human Knowledge", Popper argues that Berkeley is to be considered as an instrumentalist philosopher, along with Robert Bellarmine, Pierre Duhem and Ernst Mach. According to this approach, scientific theories have the status of serviceable fictions, useful inventions aimed at explaining facts, and without any pretension to being true. Popper contrasts instrumentalism with the above-mentioned essentialism and his own "critical rationalism".

 

Scientific Realism

 

Van Fraassen’s Critique of Scientific Realism

 

Overview

 

I.         Defining Scientific Realism

II.       Constructive Empiricism

III.     Defending the Theory-Observation ‘Dichotomy’

IV.    Critiquing Inference to the Best Explanation (IBE)

 

Defining Scientific Realism

 

What realism is not

 

Realism defined

 

Constructive Empiricism

 

Two (overlapping) possibilities:

 

•               Science aims to be true, but only once properly (but not literally) construed.

•               The language of science should be literally construed, but its theories need not be true to be good.

 

Two antirealisms

 

Differences between the two antirealisms

 

Option 1 (non-literal construals of theories): the quark theory doesn’t really say that quarks exist.

Rather statements like “Quarks exist” are useful “fictions” for theory construction, instruments for organizing data, making predictions and, generally soving set of problmes.

 

CE: the quark theory says that quarks exist, but it would still be a good theory even if quarks didn’t exist.

 

Constructive Empiricism

 

On this view, science aims to give us theories which are empirically adequate.

 

Acceptance of a theory involves as belief only that it is empirically adequate.  If we a comfortable redefining “true” as to meaning nothing other that “empirically adequate, then theories are or are not “true.”   But this is clearly far afield from the old (dare I say “quaint”) notion that scientific theories correspond to mind independent realties or “the way the world really is.”

 

(Think of the uncommitted “past life regressionist therapist” who asserts only that “past lie regression therapy” is useful.)

 

Contrast with realism: 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.

 

Empirical Adequacy vs. Truth

 

The quark model would be false but empirically adequate if quarks “didn’t exist,” but everything it said about observable things and events is true.

 

The challenge

But the CE theorist turns the tables on the SR:  What does “quarks exist” MEAN apart from “Quarks figuring prominently on our most empirically adequate theories?”

 

“Saving the phenomena”

 

Applies to future observations, unobserved but observable entities—in short, an empirically adequate theory must save all phenomena.

 

Acceptance, commitment, and belief

 

Acceptance = pro-attitude toward a theory, consists of:

 

·         Belief = pro-attitude that statements in the theory are true;

·         Commitment = pro-attitude to “confront any future phenomena by means of the conceptual resources of the theory” (1069); more pragmatic than belief

 

How this bears on realism and CE

 

Both realism and CE demand that acceptance entails the belief that a theory is empirically adequate.  But realism demand “more,” also demands belief that the theory is true.  This accounts for the value of explaining phenomena by appeal to unobservables. 

 

In place of this, CE claims that acceptance involves commitment to empirical adequacy, but to the reality of the unobservable entities which as utilized but the theory.  As a result, the value of explanation is mostly pragmatic.

 

Bas van Fraassen & the Theory-Observation Dichotomy

 

Bas van Fraassen replies to two potential objections to CE:

 

1)      Mediation Objection: If electron microscopes don’t yield direct observation, then neither does anything else.

 

2)      Mutation Objection: “Unobservability in principle” = “Observability under different circumstances”

 

Bas van Fraassen’s reply to the Mediation Objection

 

“Granted that we cannot answer this question (about how to classify observable and unobservable things) without arbitrariness, what follows?  Merely that ‘observable’ is a vague predicate.’  There are no problems with vague predicates so long as there are clear cases of ‘observables’ and clear cases of ‘unobservables.’

 

·                     A clear case of an observable is anything seen with the unaided eye.

·                     A clear case of an unobservable is a subatomic particle in a cloud chamber

So the concept of unobservability, and hence antirealism, is intelligible.

 

The “Mutation Objection”

 

The theory approach to unobservability: A theoretical entity is unobservable in principle if the theory positing it entails that it is unobservable.

 

Maxwell: If we had different perceptual capacities, any entity that is unobservable in this sense can be made observable.  So there is no difference between “unobservable in principle” and “observable under different conditions than our own.”

 

Bas van Fraassen’s reply to the Mutation Objection

 

This is just punning on any concept involving “-able,” i.e., dealing with possibility.

 

Ex. Is the Empire State Building “portable” simply because future architects could be much more ingenious than we are?

 

The proper frame of reference is with respect to “what is observable by us,” our limitations as human beings.

 

Ian Hacking: "Do We See Through a Microscope?"

 

In his article, "Do We See Through a Microscope?" (Churchland and Hooker, eds., 1985, Images of Science), Ian Hacking (1936 – 2023) argues that what convinces experimentalists that they are seeing microscopic particles has nothing to do with the “theory: of those particles or of how a microscope behaves, but that they can manipulate those particles in very direct and tangible ways to achieve certain results.

 

·         The ability to see through a microscope is acquired through manipulation.  (What is an artifact of the instrument and what is reality are learned through practice.)

 

·         We believe what we see because, by manipulation, we have found the preparation process that produces these sights to give stable and reliable results, and to be related to what we see macroscopically in certain regular ways (the Grid Argument, the electron beam arguments of "Experimentation and Scientific Realism," in Janet Kourany)

 

·         We believe what we see through a particular instrument is reliable because we can invent new and better ways of seeing it (optical microscopes, ultraviolet microscopes, electron microscopes, etc.)

 

Hacking's argument contains three elements:

 

(a)    manipulation causes cognitive changes that give us new perceptual abilities,

(b)    we can manipulate the world in such a way as to create microstructures that have the same properties as macrostructures we can observe, and that,

(c)     combined with this fact, the convergence of the various instruments on the same visual results gives us additional reason to believe that what we are seeing is real, not an artifact of any particular instrument.

 

The final element (c) seems similar to a “convergence: argument such IBE arguments. There is a difference, however, since what is at issue is not whether a single scientific theory implies things that are verified under many independent circumstances, but whether we are convinced that we are seeing something based on the fact of stable features using different viewing techniques.  Nevertheless, it is an argument from “coincidence” (wouldn't it be a miracle if all these independent viewing techniques shared stable structural features and those features weren't really present in the microscopic specimen?) and stands or falls on the same grounds.

 

However, that is not all that Hacking has at his disposal. His adds that how we acquire new modes of perception is by using instruments to manipulate a world we cannot see.  In his words, we don't see through a microscope, we see with a microscope. That is something that must be learned by interacting with the microscopic world, just as ordinary vision is acquired by interacting with the macroscopic world around us.

 

In addition, Hacking wants to argue that we come to manipulate things in ways that do not involve direct perception. This is where the example of using electrons to check for parity violation of weak, neutral currents comes in.  In this case, Hacking argues that it might have once been the case that the explanatory virtues of atomic theory led one to believe in their existence; but now we have more direct evidence.  We can now use electrons to achieve other results, and thus we are convinced of the existence of entities with well-defined, stable causal properties.

 

That does not mean that we know everything there is to know about those particles (thus, we may disbelieve any of the particular theories of the electron that are in existence); however, that there are entities with certain causal properties is shown by experience, by manipulating electrons to achieve definite, predictable results. (Hence the slogan, "If you can manipulate them, they must be real.") This is why Hacking, like Cartwright, is an entity realist, but not a realist about scientific theories.

 

Just Interesting: Bas C. van Fraassen - Critical Realism in Science and Theology


[1] "To be of service to reckoning and mathematical demonstrations is one thing, to set forth the nature of things is another" (De Motu), cited by G. Warnock in the introduction to A Treatise Concerning the Principles of Human Knowledge, Open Court La Salle, 1986, p. 24.

[2] Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge, New York: Routledge, 2002, p. 231.

[3] K. Popper Conjectures and Refutations, Part I, 3.