The Role of Thought Experiments in Science and Science Learning

This chapter will (1) briefly review selected studies examining the nature of thought experiments in science; (2) review previous studies on the role that thought experiments can play in science instruction; (3) give case study examples of thought experiments (TEs) proposed by both teachers and students and the ensuing classroom discussions. We discuss several definitions for the term thought experiment and examine methods that have the potential to illuminate issues such as the following: students can generate their own TEs as well as discuss ones proposed by the teacher; students give evidence of using imagery during TEs as indicated by certain imagery indicators; one can track how a TE spreads “contagiously” between students in a discussion and how it is modified and improved in the process. We will conclude that student TEs can be similar to expert TEs in many ways and raise possible factors that make teacher generated TEs foster student discussion and sense making. 2 Stephens TEs in Science Learning Review of selected studies on thought experiments in science experts Certain writers in philosophy of science have been intrigued with thought experiments (TEs) for some time because if effective, they seem to contradict the spirit of empiricism that dominated philosophy of science for much of the 20 century. The idea of obtaining new knowledge from internal mental manipulations alone does not sit comfortably within an empiricist framework. Authors such as David Brown (1991) and Roy Sorensen (1992) have compiled collections of TEs that were important in the history of science. By now it is widely recognized that at least some TEs in the history of science have been noticeably, if not spectacularly, germane to a scientist’s investigation, due to famous examples such as those used in the Einstein–Bohr debates on quantum mechanics. Nancy Nersessian (1992) has analyzed historical records of Maxwell’s breakthroughs in electromagnetic field theory, finding that a series of thought experiments involving gears and then fluid vortices played a role in his theory formulation. TEs also have been considered somewhat enigmatic and exotic. The reason for this is captured in what John Clement (2002) called the “Fundamental Paradox of Thought Experiments”, namely, “How can findings that carry conviction result from a new experiment conducted entirely within the head?” The idea of an experiment (involving observation) being conducted in the head (without observation) appears self-contradictory. Purposes for Thought Experiments One line of investigation is to examine the purpose served by thought experiments. Thomas Kuhn (1977) argued that the purpose of a TE is to disconfirm a theory by disclosing a conflict between ones existing concepts and nature. Undoubtedly, TEs are probably most impressive when they act to disconfirm an established theory in science; then they actually seem to be doing something as powerful as a critical experiment or anomaly can do. On the other hand, Brown (1991) identified several purposes for TEs; these included constructive as well as destructive (conflict-generating) purposes. He also theorized that a few special TEs could serve both functions. Similarly, Nersessian’s (1992) analysis of Maxwell’s work hypothesized that a TE could expose conflicts in an existing theory but also point to new constraints that help guide positive modifications of the theory, thus playing both a destructive and constructive role. Interestingly, Athanasios Velentzas, Krystallia Halkia and Constantine Skordoulis (2005) found that textbooks in relativity and quantum mechanics use constructive but not destructive TEs; they feel the inclusion of destructive TEs could increase student interest. Stephens TEs in Science Learning 3