## The Dark Side of the Force: When computer simulations lead us astray and "model think" narrows our imagination. (revised version, October 2006) |

Table of Contents |

Computer simulations can be employed in science not only for generating
explanations but for various different purposes. They can, for example,
be used to merely express certain theoretical assumptions or concepts.
In this sense they provide a sometimes weaker and sometimes stronger
but usually simpler and more flexible alternative to mathematical modeling.
Or they can be used to prove the “logical possibility”
of certain general assumptions such as the assumption that cooperation
is possible among egoists. Or they can be used to explore the possible
consequences or implications of certain assumptions. All of these previously
mentioned uses of computer simulations can be subsumed under the general
title of * exploratory simulations* or, as these are sometimes
also called, * speculative simulations*. It is the distinctive
mark of this type of simulations that the simulations do not need to
resemble empirical reality. If there exists any resemblance at all
then it is typically vague and consists in the plausibility of the
assumptions.

Another - potentially more important - class of computer simulations
are *predictive simulations*. The purpose of predictive simulations
is to generate accurate predictions for some empirical process. An
example might be simulations in meteorology that predict how the wheather
is going to be in the future. The assumptions that enter into predictive
simulations do not need to be in any way realistic. As long as the
predictions prove to be reliable, it is permissible to use strongly
simplified assumptions about the modeled process or even assumptions
which are known to be false. This shows that just because a simulation
produces successful predictions it does not necessarily also provide
an explanation for the predicted phenomena, even though successful
predictions may be one among several indicators for a simulation to
be explanatorily valid.

The most desired case, however, would be that of an *explanatory
simulation* that is a type of computer simulation that actually
allows us to explain the empirical phenomena that are modeled in the
simulation. It is this class of simulations that I am concerned with
in this paper.