2000 HSS/PSA Program 1 - History of Science Society

PSA Abstracts
computation. She calls it The Modern Church’s Thesis: “A probabilistic Turing
machine can simulate any reasonable physical device in polynomial cost.” As
they stand, these claims are rather vague (mainly because it is not readily clear
how to translate TM memory, and TM number of computation steps, into physical
space-time variables.) However, the connection can be made more precise in a
number of ways. Quantum computation seems to provide a counter example to
this thesis. Quantum computers use programs that can run on superpositions of
input states, rather than just one such state. This “massive parallelism” can,
sometimes, be used to speedup computations. The most dramatic example, so
far, is Shor’s quantum algorithm for factoring numbers that runs in polynomial
time. It is widely believed that no TM can factor numbers (into their prime
components) in so few steps. The paper will survey these developments and
their implications for the “Physical Church -Turing Thesis.”
Anya Plutynski University of Pennsylvania
Modeling Evolution in Theory and Practice
The discussion of models in philosophy of science has historically revolved
around the question of whether models in the sense of metaphors or analogies
are dispensable or critical to prediction and explanation. Today most
philosophers of science accept that models are important to theorizing, but the
focus has been primarily on mathematical models. Recent work on material,
analogical, and otherwise non-mathematical models requires philosophers of
science to reconsider the role of these types of models in scientific theory and
practice. This paper discusses how biologists use non-mathematical models
and argues that the semantic approach to evolutionary theory must
accommodate these diverse types and functions of models.
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Stathis Psillos University of Athens
Is Structural Realism Possible?
This paper examines in detail two paths that lead to Structural Realism (SR),
viz. a substantive philosophical position that places structural constraints on
the knowability of the world. The ‘upward path’ is any attempt to begin with
empiricist premises and reach a sustainable realist position. (It has been
advocated by Russell, Weyl and Maxwell among others). The ‘downward path’
is any attempt to start from realist premises and construct a weaker realist
position. (It has been recently advocated by Worrall, French and Ladyman).
The paper unravels and criticises the metaphysical presuppositions of both
paths to SR. It questions its very possibility as a substantive—and viable—
realist thesis.
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