1. education
2. graduate school

Stanford vs. Selective Realism
1
1. Background
1.1.
The Divide et Impera Argument
DI1. The theoretical laws and mechanisms (constituents) that generated the novel successes of past
theories have been retained in our current scientific theories
DI2. If the constituents that generated the novel successes of past theories have been retained in
our current scientific theories, and our current theories are approximately true, then those
constituents are also approximately true.
DI3. ∴ Even if our current theories are empirically successful, the constituents of past theories
that (a) generated the novel successes of past theories and (b) have been retained in our
current scientific theories are (c) approximately true. (From DI1, DI2)
• Stanford calls this the “selective confirmation” strategy of realists such as Kitcher and Psillos
(and Worrall).
• If sound, the Divide et Impera Argument would defend the realist’s claim that approximate truth
explains empirical success from Laudan’s Pessimistic Induction.
1.2.
The Hindsight Objection, Refined
H1.
Some theoretical constituents from past theories are judged by us to (a) have generated the
novel success of past theories, and (c) be approximately true.
H2.
The best explanation for the agreement between (a) and (c) is that we make both of these
judgments on the basis of our current theories. [probably]
H3.
∴ We judge the sources of novel success and approximate truth on the basis of our current
theories. (From H1, H2)
H4.
H3 is consistent with antirealism.
H5.
∴ The Divide et Impera Argument does not establish realism. (From H3, H4)
1.3.
How Can Realists Avoid the Hindsight Objection?
Short answer: by having a better explanation of (a) and (c) than the one offered in H2.
Longer answer: A better explanation must be prospectively applicable, i.e. it must provide some criterion X
such that:
• If a scientist is working at time t, then he/she can determine if a theoretical constituent satisfies
X at t; and
• If scientists determine that a theoretical constituent satisfies X at t, then that constituent will be
retained in all successor theories after t.
Stanford: “this is just what existing appeals to selective confirmation do not (and perhaps cannot)
provide.” (915)
2. Hardworking Posits
2.1.
Kitcher’s View
Scientists deploy (often-implicit) problem-solving schemas to generate empirical success.
Working posits are theoretical constituents that actually generate novel success.
Presuppositional posits are theoretical constituents that apparently have to exist if the instances of the
problem-solving schema are to be true.
Kitcher: The Pessimistic Induction shows that presuppositional posits are suspect, but we can see
retrospectively that working posits refer to entities that our current theories take to exist.
• Ex. Scientists from Fresnel to Maxwell (i.e. most of the 19th century) had significant and novel
empirical success by positing that light and electromagnetic forces traveled in waves through a
mechanical medium (the ether). However, closer inspection shows that the wave posit did all of
the work in generating the empirical success; and the ether posit was not necessary, i.e. merely
presuppositional or idle.
Stanford vs. Selective Realism
2
2.2.
Stanford’s 1st Objection
1.
For any working posit H, there is some novel success E, such that it is impossible to
generate E without H.
2.
It is always possible to posit an uninformative claim that would generate E but without H,
e.g. “There is some causal material basis for E.”
3.
∴ There are no working posits; only presuppositional posits. (From 1,2)
2.3.
Stanford’s 2nd Objection
1. If selective confirmation is to rebut the Pessimistic Induction, then for all H, scientists should be
reliable in applying prospectively applicable criteria to determine whether or not H is a working
posit.
2. Scientists are not reliable in applying these criteria.
3. ∴ Selective confirmation does not rebut the Pessimistic Induction.
• Stanford considers two potential prospectively applicable criteria:
o Scientists must find it intelligible to have a well-confirmed theory without a presuppositional
posit.
o Scientist must not assign a presuppositional posit any direct causal role.
General lesson: the false constituents seem to play just as much of a role (“work just as hard”) as the
true constituents in generating the empirical successes.
3. Trusting Scientists
Psillos differs slightly in that he does not think that we need an explicit criterion that is prospectively
applicable; whatever criteria scientists use to discriminate “working” and “idle” posits is adequate.
(This allows him to entertain the possibility that different scientists at different times may use
different criteria to sift through these posits/constituents.)
3.1.
Psillos’ Trust Argument
1. For all H and E, H is a theoretical constituent that generates a novel empirical success p if and
only if E is a novel success first discovered at time t, and scientists at t believe that H is a
theoretical constituent that generated a novel success E.
2. During the 19th century, scientists did not believe that ether and caloric per se generated novel
successes; they believed that other parts of these theories generated the novel successes.
3. ∴ Ether and caloric did not generate novel successes.
3.2.
Stanford’s 1st Objection
During the 19th century, scientists did not believe that they had correctly described the ether and caloric,
but they did believe that the ether and caloric existed and that it was indispensable to the theory’s
empirical successes.
3.3.
Stanford’s 2nd Objection
1. At any given t in which a novel success E is first discovered, scientists at t disagree about whether
H is a theoretical constituent that generated a novel success E.
2. If scientists at disagree about whether H is a theoretical constituent that generated a novel success
E, then they do not (collectively) believe that H is a theoretical constituent that generated a novel
success E.
3. ∴ When a novel success E is first discovered, scientists do not (collectively) believe that H is a
theoretical constituent that generated a novel success E. (From 1, 2)
4. If the Trust Argument is sound, then for all H and E, H is a theoretical constituent that generates
a novel empirical success E if and only if E is a novel success first discovered at time t, and
scientists at t believe that H is a theoretical constituent that generated a novel success E.
5. ∴ If the Trust Argument is sound, then there is no theoretical constituent that generates a novel
empirical success. (From 3, 4)