To save the phenomena: constructive empiricism

1. To save the phenomena: constructive empiricism [The] belief involved in accepting a scientific theory is only that it ‘saves the phenomena’, that is that it correctly describes what is observable (van Fraassen,185-186)

2. Term paper and final exam • Final exam is scheduled for Thursday April 19, 6 pm in SBE 1220 • Term paper is due March 22nd. Hard copy to me and electronic copy to Turnitin.com. Note the proviso in penalty for late submissions however • Please set up your account at Turnitin.com and familiarize yourself with the site before the due date. • Remember you are presenting an argument in support of a conclusion in your paper. You cannot just string together quotes!

3. Steps leading to constructive empiricism • What is the argument used by anti-realists to motivate our acceptance of their position? • Strong underdetermination • For every theory there exist an infinite number of strongly empirically equivalent but incompatible rival theories • If two theories are strongly empirically equivalent then they are evidentially equivalent • No evidence can ever support a unique theory more than its strongly empirically equivalent rivals • Therefore, theory-choice is radically underdetermnined.

4. Steps leading to constructive empiricism • Focus on the second premise: If two theories are strongly empirically equivalent then they are evidentially equivalent • Distinguish between empirical and evidential equivalence • Theory choice involves non-empirical features. E.g. Kinetic theory of motion

5. Steps leading to constructive empiricism • What is the constructive empiricist’s response to the challenge? • The underdetermination is resolved by pragmatic considerations, not epistemological ones

6. Scientific realism: “science aims to give us … 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 cited on 185) Constructive empiricism: “science aims to give us theories which are empirically adequate, and acceptance of a theory involves … belief only that it is empirically adequate” (ibid) The difference between Scientific realism and Constructive Empiricism

7. The realist thinks science aims at truth with respect to unobservable processes and entities that explain observable phenomena The constructive empiricist thinks that science aims to tell the truth about what is observable and rejects the demand for explanation for all regularities in what we observe; they are agnostic with respect to unobservables Difference between scientific realism and constructive empiricism

8. The realist fights back: defending scientific realism against constructive empiricism • Challenge the observable/unobservable distinction • Acceptance of theory involves a commitment to interpret and talk about the world in its terms • The strong form of the underdetermination argument applies to both unobservables and observables. The constructive empiricist is guilty of selective skepticism. The constructive empiricist is being inconsistent.

9. First objection: observable/unobservable • First objection: no meaningful distinction can be drawn between the observable and the unobservable. Furthermore, no epistemological significance hangs on the distinction. • The realist’s point is that there is nothing special about unobservable entities that prevents us knowing about their existence. That is, “nothing is unobservable in principle” (Ladyman 188). • This point was raised by Grover Maxwell in 1962.

10. Observable/unobservable distinction • Maxwell: there is a continuum between seeing normally, seeing with binoculars, seeing with a microscope, seeing with an electron microscope. Where is the line between observable and unobservable? • van Frassen: vague predicates, like ‘red’, ‘tall’, can do epistemological work. • van Frassen: what we can and cannot know coincides with the observable and unobservable.

11. Reply to the first objection • van Fraassen’s aim: skepticism about unobservable. • Maxwell: nothing is unobservable in principle. This means that entities may be observed under the right sort of circumstances. Electron microscope, for example. • For van Frassen, ‘observable’ is to be understood as observable-to-us: “X is observable if there are circumstances which are such that, if X is present to us under those circumstances, then we observe it” (188).

12. Reply to the first objection • What we can or cannot observe is due to the fact: “the human organism is, from the point of view of physics, a certain kind of measuring apparatus. As such it has certain limitations … it is these limitations to which the ‘able’ in ‘observable’ refers—our limitations qua human beings” (189)

13. Reply to the first objection • The ‘us’ refers to the human epistemic community. The epistemology is our epistemology • However, if in the future, we encounter other beings whose senses are better than ours, and the two epistemic communities are integrated, then the observable/unobservable boundary shifts appropriately. We would be at the sight-impaired end of the community

14. Reply to the first objection • What then is the difference between the moons of Jupiter and positrons? • Were we in a space ship and were close enough to Jupiter, we would observe the moons of Jupiter. • However, we do not directly observe positrons. We infer their existence by the tracks in a cloud chamber. • There may well be another theory which is empirical equivalent but denies that positrons exist—the leprechaun theory.

15. Reply to the first objection • The realist may object: “why does van Frassen allow change in spatiotemporal location when determining what is observable, but not the constitution of our sensory organs?” • van Frassen’s response: we are like beings whose only difference is that they are closer to Jupiter, but we are not like beings with different sensory organs. • If we had electron microscopic eyes, we might not observe positrons.

16. Second Objection: Acceptance and belief • The objection: Acceptance of theory involves a commitment to interpret and talk about the world in its terms • The scientific realist challenges van Fraassen’s distinction between belief and ‘acceptance’: the realist argues that van Fraassen’s position is incoherent.

17. Second objection • The difference between belief and acceptance • Does the following statement ‘I believe p (p be any statement) but it is not true’, make sense? • Believing in p implies one is committed to the truth of p • van Frassen claims that ‘I accept p’ does not imply that one is committed to the truth of p. • Is he right?

18. Reply to second objection: • Does it make sense to say that ‘I accept p but p is not true’? Is there a contradiction in saying ‘I accept p but p is not true’? • Consider the case of Newtonian mechanics • We accept it for use everyday but we are not committed to saying that it is true, which it isn’t strictly speaking.

19. Belief and acceptance: • The above example illustrates the difference in epistemic attitude between believing in and accepting a statement, or theory. • There appears to be no contradiction in accepting a theory for use but believe it to be false. • The realist objection fails.

20. Third objection: selective skepticism • In order to appreciate the third objection, we need to consider what realists mean by ‘explanation’? • Realists hold that the truth (or approximate truth) of a hypothesis is a necessary condition for it to be part of a genuine scientific explanation. • That is why, for realists, explanations require more than empirical adequacy (what is ‘empirical adequacy?)

21. Scientific explanations • Realists argue that there are principled ways of breaking underdetermination. A rational justification can be offered. • For them, inference to the best explanation (IBE) shows that empirical equivalence of theories does not imply evidential equivalence. • Realists use IBE to argue for the existence of unobservables. • The constructive empiricist must offer a critique of IBE if they are to succeed in arguing their case.