Thought experiments have played a central role in historical cases of major conceptual change in science. They are important in both constructing new representations of nature and in conveying those representations to others. It is proposed that research into the role of mental modelling in narrative comprehension can illuminate how and why thought experiments work. In constructing and "running" the thought experiment, we make use of inferencing mechanisms, existing representations, and general world knowledge to make realistic transformations from one possible physical state to the next and this process reveals impossibility of applying existing concepts to the world and pinpoints the locus of needed conceptual reform.

We discuss the process of mathematization in science, focusing on uses that theorists make of physical representations that w e refer to as abstracted models. W e review abstracted models constructed by Faraday and Maxwell in the mathematization of electromagnetic phenomena, including Maxwell's use of an analogy between continuum dynamics and electromagnetism. W e discuss ways in which this example requires major modifications of current cognitive theories of analogical reasoning and scientific induction, especially in the need to understand the use of abstracted models containing theoretically meaningful objects that can be manipulated and modified in the development of new concepts and mathematized representations.

Are students' explanations of motion generated by an underlying structure? We address this question by exploring striking parallels between intuitive explanations and those offered by medieval scholastics. Using the historical record, it is possible to reconstructan inferential structure that generates medieval explanations. W e posit a parallel structure for intuitive explanations.