Validation of Computer Simulations from a Kuhnian Perspective

Contents

3 A revolution, but not a Kuhnian revolution: Computer simulations in science

Kuhn's theory of scientific revolutions is so popular that his concept of a paradigm has by now become part of the common vocabulary. Inevitably, it is often used in a sense that is different from what Kuhn had in mind. It may therefore help to make clear what is not a revolution or paradigm change in Kuhn's sense. A most salient example in this context is that of the introduction of computer simulations to science, because it can with some justification be said that computer simulations have revolutionized many areas of science. these really Kuhnian revolutions?

Computer simulations can roughly be defined as the imitation of a natural process (or, in the case of social simulations, a social process) by a computer program (Hartmann 1996). Undoubtedly, computer simulations have brought about considerable changes in scientific practice and theoretical outlook. Here are but some examples:

• In engineering, simulations have been used before long to simulate the properties of machinery and processes. A large class of simulations is based on the method of finite elements which has as far reaching applications as structural engineering, car crash tests and even cardiovascular simulations (Carusi et al. 2013).
   
• In chemistry simulations are employed in order to simulate chemical processes on a quantum-mechanical bases, some of which are even outside the reach of direct experimentation (Arnold/Kaestner 2013).
   
• In climate science the simulations are used to simulate the possible future development of the world climate. Naturally, experimentation with the world climate is not possible. By the same token, unfortunately, these simulations cannot be validated directly.
   
• The theory of non-linear dynamical systems (“chaos theory”) can even be said to owe much of its origin to computational methods (Gleick 2011). At any rate its development has certainly been propelled by the use of computers, though it might not necessarily have been computer simulations in the narrower sense of imitations of a natural process in the computer.
   
• In social science there exists a now already long standing tradition of simulating social processes. However, the social simulations community still struggles for the acceptance within the broader social sciences community (Squazzoni/Casnici 2013).

Some of these examples certainly warrant the characterization as “revolutionary”. Are they revolutionary in a Kuhnian sense, though? And would it be reasonable to call simulation-based science in general a new paradigm of science?

For one thing, the way Kuhn used the term paradigm, paradigms are always tied to specific scientific disciplines. Even though we are not tied to Kuhn's definition and the term paradigm has indeed been used more liberally by other authors since its original introduction, it would appear a bit vague to speak of a paradigm of computer simulations, because it is not at all clear what would be the content of this paradigm.

Even more importantly, Kuhn reserves the concept of scientific revolutions for changes that are caused by a crisis of the conceptual framework of a scientific discipline and that lead to a reconstruction of the conceptual system that is incommensurable with the previous reference framework. Not any dramatic change in science is a revolution in the Kuhnian sense. A prominent example for a dramatic change that is not a Kuhnian revolution is the discovery of the structure of the DNA-molecule by Watson and Crick. While this discovery was a door-opener for molecular genetics, it neither required nor effected a conceptual reconstruction and there was no question of it being incommensurable with the previously held views on hereditary biology. Quite the contrary, it fit in nicely with the existing body of knowledge. The discovery of the DNA was normal science at its best, not a Kuhnian revolution.

Similarly, the introduction of computer simulations into a particular branch of science alone is not a Kuhnian revolution, no matter how dramatic the changes in scientific practice and the extension of our knowledge through computer simulations might be. Only, if the use of computer simulations leads to a revision of established fundamental concepts, it is a Kuhnian revolution. A possible candidate from the list above might be chaos theory, in so far as it has modified the received picture of causality.

t g+ f @