Phil. Science Notes 4/14/11
Van Fraasen’s Goal: To examine and critique arguments of scientific realism.
Realism is a response to positivism. He will offer constructive empiricism (CE) which is at odds with both
logical positivism and the realists. Realism: literal science, acceptance of a theory means belief that it is
true. He offers alternatives to realism. Anti-realism: the aim of science can be achieved without the
belief that the theory is itself actually true.
What do scientists do? Realists—scientists propose a theory to assert its truth. Anti-realists—a scientist
displays a theory and proposes its virtue.
Anti-realists divide into two groups: 1) Science aims to be true, but not literally true. For example,
scientists offer a different conception of truth, truth as pragmatic. 2) The language of science is literal,
but not conceived as true. This group has the same conception of truth as realists, but believes that
truth does not apply to scientific theories.
CE falls into the second group. He explains that under CE we should accept only theories that are
empirically adequate. Empirical adequacy is met when a theory has a model where all of the
phenomena fit into the model.
What would a paradigm shift look like under realism? The old theory was not true. Under CE? The old
model was not empirically adequate. There may be an advantage either way for explaining paradigm
shifts.
Theory/Observation dichotomy—Realists: theory cannot be distinguished from observation. The
motivation for anti-realists is that we have better epistemological access to observable entities. Maxwell
argues that theory/observation cannot be distinguished. We cannot classify objects into
observable/non-observable. Maxwell wants to get clear the distinction between
observable/unobservable. The idea that something is observable is that is can be observed without aid.
There is a continuum of what is observable and unobservable.
Van Fraasen response: Can we divide langue into theoretical vs. observable? No. Can we divide between
observable and unobservable? Van Fraasen says ‘yes.’ ‘Observable’ classifies putative entities. (Flying
horses are observable, whereas the number 17 is not.) It is a vague concept—one in which we cannot
specify identity conditions in which it holds or not (e.g. baldness). Just because something is vague does
not mean there is not a clear case of it. What we count as observable is intended to a certain and to
what it is that we observe at that time.
Inference to the best explanation—a realist argument that suggests we should infer the theory that best
explains evidence. Does this lead to realism or require it? Mouse example; if we hear little footsteps and
notice the cheese is missing, we infer that we have a real mouse. Can it lead us to unobservable
entities? Van Fraasen claims that to use inference to the best explanation is to develop a psychological
hypothesis, one that is empirically adequate. It is not clear that we need to posit a real entities. The
realist hypothesis is no more warranted than is his.
Limits of the demand for explanation—realists argue their theories have the most explanatory power
because they can distinguish between a theory being merely correct and being useful. If usefulness is
not the only criteria then realist theories are more correct. Van Fraasen counters that this succeeds only
if we assume the demand for explanation is supreme. We should not insist on further explanation. Every
explanation has to stop somewhere. The realist claims instrumentalists stop at observations so we
should keep going down. Van Fraasen claims that if we are required to explain, the realist theory itself
needs to be maintained. You will never be able to stop explaining. There is nothing wrong with stopping
at observable entities.
Can a realist give a principled defense of stopping at “real objects” as opposed to “observable
regularities?”
Gold Example—chemists notice differences in dissolving of gold, then develop two theories as to why.
There is no explanation without reference to the unobservable. Do the unobservables cause a change in
what is seen? Van Fraasen says ‘yes’ it does. Sellars says the demand for explanation is antithetical to
quantum mechanics. Van Fraasen counters that science has rejected the hidden variable explaining
differences via Quantum Mechanics.