- This book presents a general theory of thought experiments2: what they are; how they work; their virtues and vices. Since my aim is synoptic, a wide corpus of thought experiments3 has been incorporated. There is a special abundance of examples from ethics and the metaphysics of personal identity because thought experiments4 in these areas have recently attracted heavy commentary. But the emphasis is on variety, rather than quantity. Thus, the discussion ranges over thought experiments5 from many disparate fields, from aesthetics to zoology.
- Scientific thought experiments6 — especially those in physics — are the clear cases, so my primary goal is to establish true and interesting generalizations about them. Success here will radiate to my secondary goal of understanding philosophical thought experiments7. The reason for this optimism is subscription to a gradualistic metaphilosophy: philosophy differs from science in degree, not kind. Understand science, understand the parameters to be varied, and you understand philosophy.
- My basic means of reaching these two goals is to let the surface grammar of 'thought experiment8' be my guide and to pitch this book as part of the growing literature on experiment. Philosophers and historians of science have long followed the elder statesmen of science in concentrating on theory; experimentation has been dismissed as a rather straightforward matter of following directions and looking at gauges. Within the last ten years, the "just look and see" picture has been rejected in favor of one that assigns deeper roles for experimenters: creating and stabilizing phenomena; atheoretical exploration; and defining concepts by immersion in laboratory practice. Sympathy with this movement, coupled with the belief that thought experiments9 are experiments, led me to suspect a corresponding oversimplification of the thought experimenter10's role.
- The main theme of this book is that thought experiment11 is experiment (albeit a limiting case of it), so that the lessons learned about experimentation carry over to thought experiment12, and vice versa. For the symmetry of 'similar' underwrites a two-way trade; if thought experiments13 are surprisingly similar to experiments, then experiments are surprisingly similar to thought experiments14. In particular, experiments exploit many of the organizational effects associated with the products of armchair inquiry. Study of thought experiments15 draws attention to these neglected features of ordinary experiments; for when we explain the informativeness of thought experiment16, we cannot appeal to the inflow of fresh information. We are forced to look for ways that old information can be rendered more informative. (Consider how nineteenth-century investigations into animal behavior illuminated human psychology just because researchers had to make do with behavior; the distraction of introspection was removed.) Once these repackaging effects are detected with thought experiments17, they can be spotted in ordinary experiments. However, most of the illumination will flow from ordinary experiment to thought experiment18; I shall mainly use the familiar to explain the obscure.
- Chapter 1 ("Sorensen (Roy) - Our Most Curious Device") motivates the study of thought experiments19 — in broad strokes. Detailed structuring of the issues begins by making chapter 2 ("Sorensen (Roy) - Scepticism About Thought Experiments") a forum for sceptics. Thus, the technique looks discredited by the time sceptics yield the floor to Ernst Mach in chapter 3 ("Sorensen (Roy) - Mach and Inner Cognitive Africa"). This criticism is followed by a chapter ("Sorensen (Roy) - The Wonder of Armchair Inquiry") on armchair inquiry which will give us more breadth.
- Special use will be made of the cleansing model of armchair inquiry. It presents intellectual improvement as the shedding of intellectual vices, rather than the acquisition of virtues. Rationality is portrayed as analogous to health: just as health is the absence of disease, rationality is the absence of irrationalities. Thus, thought experiments20 make us more rational by purging us of bias, circularity, dogmatism, and other cognitive inefficiencies. All experiments work by raising the experimenter's status as an epistemic authority. Ordinary experiments confer authority mainly by improving the experimenter's perceptual abilities and opportunities. Thought experiments21 focus on nonperceptual improvements. But since an ordinary experiment can simultaneously provide perceptual and nonperceptual improvements, study of thought experiments22 can bring a neglected side of ordinary experiments into sharp relief.
- Inconsistency is the most general and best understood of cognitive flaws. This invites a reduction thesis23: all of the irrationalities eliminated by thought experiment24 can be formulated as inconsistencies. If this thesis is true (and I think it is), we need only standardize the format of thought experiments25 in order to apply standard logic directly. So while granting that all of the models of armchair inquiry have something to offer, I close the chapter with the conclusion that the reductionist26 version of the cleansing model offers the best chance for immediate elaboration.
- Thomas Kuhn argued that thought experiments27 revealed a special kind of contradiction — a type of local incoherency. I try to salvage the insight driving Kuhn's heresy in chapter 5 ("Sorensen (Roy) - Kuhntradictions"). A paradox is a small set of individually plausible yet jointly inconsistent propositions. In chapter 6 ("Sorensen (Roy) - The Logical Structure of Thought Experiments") I extrapolate to the thesis that every thought experiment28 is reducible29 to such a set.
- The official role of thought experiment30 is to test modal31 consequences. The apparent narrowness of its function eases once we realize that there are many kinds of necessity: logical, physical, technological, moral. But the real flexibility of thought experiments32 wriggles up from the indirect uses of this official procedure. Just as jokes, metaphor, and politeness are conveyed through trick bounces off conventions governing literal conversation, thought experimenters33 use the standard format obliquely to transact a rich array of side tasks; concocting counterexamples to definitions and "laws," expanding the domain of theories, exhibiting modal34 fallacies, deriving astounding consequences, suggesting impossibility proofs.
- The paradox analysis is further deepened in chapter 7 ("Sorensen (Roy) - Conflict Vagueness and Precisification") by a special application to the genre of thought experiments35 that fascinated Kuhn. Having taken Kuhn's insight as far as I can, chapter 8 ("Sorensen (Roy) - The Evolution of Thought Experiments") returns thought experiments36 to their unregimented state. The suspicion that 'thought experiment37' is a systematically misleading expression is addressed in chapter 9 ("Sorensen (Roy) - Are Thought Experiments Experiments?").
- My final chapter ("Sorensen (Roy) - Fallacies and Antifallacies") assesses the hazards and pseudohazards of thought experiment38. If there are sides to be taken, I count myself among the friends of thought experiment39.
Photocopy of complete Book filed in "Various - Papers on Identity Boxes: Vol 17 (S2: Sm+)".
Footnote 1: But with Chapter summaries excerpted to the relevant Chapters.
Text Colour Conventions (see disclaimer)
- Blue: Text by me; © Theo Todman, 2019
- Mauve: Text by correspondent(s) or other author(s); © the author(s)