part 4: philosophy of science: realism vs instrumentalism

AN INTRODUCTION TO PHILOSOPHY OF SCIENCE

PART 4John Ostrowick

john@ostrowick.com

SO FAR…• So far…

• In part 1, we saw how formal logic works

• We’ve seen some fallacies.

• We’ve seen the difference between induction, deduction and abduction.

• In part 2, we identified that induction is fallacious (logically)

• We saw that there’s a problem of induction which says that we can’t generalise (past to future, token to type, etc)

• Yet science generalises.

SO FAR…• So far…

• We saw that we can instead argue that science uses probability claims

• We saw how Bayes’ Theorem works

• And we saw some problems with it, like how to fix the prior probabilities.

• We saw that we can fix the priors with frequentism or propensity.

• We saw that background knowledge can influence believability.

• We saw that there’s a problem with deciding what evidence is relevant.

SO FAR…• So far…

• In part 3, we saw how science tries to explain observations. We saw:

• There’s a problem with the notion of causation

• That we need to distinguish causation and correlation

• There’s a question of curve-fitting, simplicity, predicting evidence, theoretical fit, and extrapolation

SO FAR…• So far…

• We saw the problem of underdetermination of theory by evidence and

• Occam’s Razor and Simplicity and

• Other measures of a good explanation and

• The problem of theory-laden observations.

INTRODUCTION

• In this part, we ask: Is science finding truth?

• In this section, we discuss the problem of realism; that is, if we can’t be sure that we’re seeing causal relationships, and we can’t be sure that our observations are objective, then, are we seeing reality and finding truths when we do science?

REALISM VS INSTRUMENTALISM

• Introduction

• Kuhn’s Structure of Scientific Revolutions is probably the most famous book that addresses the question of how science progresses. How does it progress?

• Logical Positivism and verificationism: the true is the observable and measurable. But… theory-laden observation. So, what is science doing?

REALISM VS INSTRUMENTALISM

•What is real?

REALISM VS INSTRUMENTALISM

• Realism

• Truth is “out there” waiting to be discovered by science.

• Surely we can say we know D.N.A exists, atoms exist…?

• F = G M1 M2 / r^2 applies to the whole universe, as far as we can see.

Source: T. Splettstoesser Wikimedia Commons

REALISM VS INSTRUMENTALISM

• Realism

• Hacking (1983). If a number of different theories, or different observation methods, converge on a particular entity as the explanation for the phenomena in question, then they corroborate or support each other. Electricity and electrons.

• Another way to make this argument is to claim that the entities in question (e.g. atoms) are indispensable for an explanation, and that it is successful because of those entities. So, for example, germ theory.* Moreover, we have subsequently observed germs, e.g. with microscopes, so, they are real.

• Manipulation. Computers and GMOs

REALISM VS INSTRUMENTALISM

• Realism: The No Miracles Argument (NMA)

• This argument claims that if science were not finding facts about the universe, it would be a miracle that it continued to work. Thus, unless science’s success would otherwise just be a sustained miracle, it must be the case that science works because it, in some sense, is accurately reflecting how the world really is.

• But this requires that “Truth” means that whatever we say “corresponds” to how the world is. The trouble is, (a) Descartes, and (b) Particle Physics. Many objectors to correspondence.

REALISM VS INSTRUMENTALISM

• Realism: The No Miracles Argument (NMA)

• Question-begging: NMA says:

1. Science has progressed.

2. Realism provides us with a theory closer to realism than any other philosophy of science.

3. We should believe the philosophy of science that is closest to realism.

4. Therefore, we should believe that realism is true. (Singer).

REALISM VS INSTRUMENTALISM

• Realism: The No Miracles Argument (NMA)

• Base rate fallacy. We don’t know how many theories have been discarded thus far, and therefore we can’t say that science is successful on the basis of the frequency with which theories are successful or discarded.

REALISM VS INSTRUMENTALISM

• Realism: Verisimilitude

• Newton-Smith (1996), (and Popper, 1972, pp. 231–236) argues that if something is scientific, it will more likely be true, if it is a product of a scientific process of increasing refinement of truth, by systematically weeding out bad theories. “Veri” meaning truth, and “similitude”, meaning “likeness”. So, as science progresses, we approach the real (realist, physical truth), by means of increasing verisimilitude.

• Objections: (a) Truth isn’t a matter of degree, and (b) Base-rate fallacy again. We can’t say we’re closer to truth without knowing the base rate.

REALISM VS INSTRUMENTALISM

• Kuhn and the Paradigm Shift

• Science is ‘bursty’ with periods of ‘normal science’ and short periods of ‘revolutionary science’, followed by a ‘paradigm shift’.

• E = ½ mv^2 versus E = mc^2

• Was Newton “wrong” or … what?

• Therefore science isn’t finding “truth”

REALISM VS INSTRUMENTALISM

• Pragmatism and Instrumentalism

• If science isn’t finding truth…

• In the late 1890s, William James, and another author, Charles Sanders Peirce (pronounced “purse”), came up with a theory of knowledge called ‘pragmatism’. For all intents and purposes, we can act as if a belief is true, and we can use the belief (or theory), as if it were true, without committing to the view that it is really in actual fact, true.

REALISM VS INSTRUMENTALISM

• Pragmatism and Instrumentalism

• If science isn’t finding truth…

• Scientists are just finding formulas and theories that are practically useful, e.g. for predicting the results of scientific experiments.

REALISM VS INSTRUMENTALISM

• Pragmatism and Instrumentalism

• Consider quantum mechanics (the Uncertainty Principle), quantum chromo-dynamics (quarks), and string theory. Which of these is true? Quantum mechanics has some strong empirical support, but the other theories less so. Indeed, as far as I know, string theory is currently only mathematical.

• We can’t say anything “true” about an electron’s position, momentum, energy, velocity, etc., without losing track of one of those.

REALISM VS INSTRUMENTALISM• Pragmatism and Instrumentalism: Bohm and Hidden

Variables

• One response to quantum mechanics in particular is a theory supported by Einstein (“God does not place dice with the universe”), or Bohm. They both held that there was some “hidden variable” in quantum mechanics which we simply were not aware of, or did not understand, that causes wave function collapse; that is, that the wave function collapse is not in fact random, but rather, just inexplicable, because we do not know what the hidden variable(s) are.

REALISM VS INSTRUMENTALISM

• Realism and imposition

• If some theory is true, may you impose it on someone?

• If a theory is just useful, you don’t feel inclined to impose it on someone.

• We’ll look at examples later.