Newton's bucket, Einstein's elevator, Schrödinger's cat – these are some of the best-known examples of thought experiments in the natural sciences. But what function do these experiments perform? Are they really experiments at all? Can they help us gain a greater understanding of the natural world? How is it possible that we can learn new things just by thinking? In this revised and updated new edition of his classic text _The Laboratory of the Mind_, James Robert Brown continues to defend (...) apriorism in the physical world. This edition features two new chapters, one on “counter thought experiments” and another on the development of inertial motion. With plenty of illustrations and updated coverage of the debate between Platonic rationalism and classic empiricism, this is a lively and engaging contribution to the field of philosophy of science. (shrink)

According to a widely held view of science, scientific hypotheses are evaluated on the basis of observational data in accordance with the rules of inductive logic. Inductive logic, like deductive logic, is supposed to consist of a set of formal rules. These rules abstract from any details of the specific hypothesis under examination, the context in which the evaluation is taking place, and the individuals who carry out the evaluation. Observational data are also independent of the context or the observer (...) in the following sense: there may be individual and cultural limitations on what observations are undertaken, but the outcome of an observation procedure is presumably independent of the observer's preferences or peculiarities. Now, given impersonal data and a set of formal rules, the assessment of a hypothesis will be completely impersonal. The fact that a scientist thinks of a hypothesis and undertakes to evaluate that hypothesis may depend on individual features of that scientist and on the current state of science, but the resulting evaluation will be free of individual, historical, or cultural factors. Any two scientists who evaluate a hypothesis on the basis of the same observational evidence must arrive at the same evaluation of that hypothesis. (shrink)

: An examination of two thought experiments in contemporary physics reveals that the same thought experiment can be reanalyzed from the perspective of different and incompatible theories. This fact undermines those accounts of thought experiments that claim their justificatory power comes from their ability to reveal the laws of nature. While thought experiments do play a genuine evaluative role in science, they do so by testing the nonempirical virtues of a theory, such as consistency and explanatory power. I conclude that, (...) while their interpretation presupposes a whole set of background theories and putative laws, thought experiments nonetheless can evolve and be retooled for different theories and ends. (shrink)

Are thought experiments nothing but arguments? I argue that it is not possible to make sense of the historical trajectory of certain thought experiments if one takes them to be arguments. Einstein and Bohr disagreed about the outcome of the clock-in-the-box thought experiment, and so they reconstructed it using different arguments. This is to be expected whenever scientists disagree about a thought experiment's outcome. Since any such episode consists of two arguments but just one thought experiment, the thought experiment cannot (...) be the arguments. (shrink)

Why should a thought experiment, an experiment that only exists in people's minds, alter our fundamental beliefs about reality? After all, isn't reasoning from the imaginary to the real a sign of psychosis? A historical survey of how thought experiments have shaped our physical laws might lead one to believe that it's not the case that the laws of physics lie - it's that they don't even pretend to tell the truth. My aim in this paper is to defend an (...) account of thought experiments that fits smoothly into our understanding of the historical trajectory of actual thought experiments and that explains how any rational person could allow an imagined, unrealized (or unrealizable) situation to change their conception of the universe. (shrink)

Galileo claimed inconsistency in the Aristotelian dogma concerning falling bodies and stated that all bodies must fall at the same rate. However, there is an empirical situation where the speeds of falling bodies are proportional to their weights; and even in vacuo all bodies do not fall at the same rate under terrestrial conditions. The reason for the deficiency of Galileo’s reasoning is analyzed, and various physical scenarios are described in which Aristotle’s claim is closer to the truth than is (...) Galileo’s. The purpose is not to reinstate Aristotelian physics at the expense of Galileo and Newton, but rather to provide evidence in support of the verdict that empirical knowledge does not come from prior philosophy.Author Keywords: Author Keywords: Aristotle; Galileo; Thought experiments; Falling bodies. (shrink)

My theme is thought experiment in natural science, and its relation to real experiment. I shall defend the thesis that thought experiments that do not lead to theorizing and to a real experiment are generally of much less value that those that do so. To illustrate this thesis I refer to three examples, from three very different periods, and with three very different kinds of status. The first is the classic thought experiment in which Galileo imagined that he had, by (...) pure thought, demolished Aristoteles' dogma that heavier bodies fall more quickly than light ones. I will show that he was mistaken. The second is the Einstein-Podolsky-Rosen paper purporting to show that quantum mechanics must be incomplete in its domain of application. This thought experiment is a very good one, not because its conclusions are correct, but precisely because it was fruitful, leading to theory and, above all, to a real experiment. Finally I discuss the modern string theory of everything, which, while it is regarded as a physical theory by its instigators, shares some properties of the least successful sort of thought experiment. (shrink)

Against Norton's claim that all thought experiments can be reduced to explicit arguments, I defend Brown's position that certain thought experiments yield a priori knowledge. They do this, I argue, not by allowing us to perceive “Platonic universals” (Brown), even though they may contain non-propositional components that are epistemically indispensable, but by helping to identify certain tacit presuppositions or “natural interpretations” (Feyerabend's term) that lead to a contradiction when the phenomenon is described in terms of them, and by suggesting a (...) new natural interpretation in terms of which the phenomenon can be redescribed free of contradiction. (shrink)

Achieving understanding of nature is one of the aims of science. In this paper we offer an analysis of the nature of scientific understanding that accords with actual scientific practice and accommodates the historical diversity of conceptions of understanding. Its core idea is a general criterion for the intelligibility of scientific theories that is essentially contextual: which theories conform to this criterion depends on contextual factors, and can change in the course of time. Our analysis provides a general account of (...) how understanding is provided by scientific explanations of diverse types. In this way, it reconciles conflicting views of explanatory understanding, such as the causal-mechanical and the unificationist conceptions. (shrink)

Sorensen presents a general theory of thought experiments: what they are, how they work, what are their virtues and vices. On Sorensen's view, philosophy differs from science in degree, but not in kind. For this reason, he claims, it is possible to understand philosophical thought experiments by concentrating on their resemblance to scientific relatives. Lessons learned about scientific experimentation carry over to thought experiment, and vice versa. Sorensen also assesses the hazards and pseudo-hazards of thought experiments. Although he grants that (...) there are interesting ways in which the method leads us astray, he attacks most scepticism about thought experiments as arbitrary. They should be used, he says, as they generally are used--as part of a diversified portfolio of techniques. All of these devices are individually susceptible to abuse, fallacy, and error. Collectively, however, they provide a network of cross-checks that make for impressive reliability. (shrink)

This essay attempts to demonstrate that it is doubtful if Galileo's famous thought experiment concerning falling bodies in his 'Dialogues Concerning Two New Sciences' (Galileo 1954: 61-64) actually does succeed in proving that Aristotle was wrong in claiming that "bodies of different weight […] move […] with different speeds which stand to one another in the same ratio as their weights," (Galileo 1954: 61). (Part I); and further that it is likewise doubtful that that argument does or even can establish (...) Galileo's own famous 'Law of Falling Bodies,' viz., that regardless of their weight all bodies fall with the same speed. (Part II). (shrink)

Canadian Journal of Philosophy, 26, pp. 333-66. 1996.

Thought experiments in science are merely picturesque argumentation. I support this view in various ways, including the claim that it follows from the fact that thought experiments can err but can still be used reliably. The view is defended against alternatives proposed by my cosymposiasts.

Contemplating imaginary scenarios that evoke certain sorts of quasi‐sensory intuitions may bring us to new beliefs about contingent features of the natural world. These beliefs may be produced quasi‐observationally; the presence of a mental image may play a crucial cognitive role in the formation of the belief in question. And this albeit fallible quasi‐observational belief‐forming mechanism may, in certain contexts, be sufficiently reliable to count as a source of justification. This sheds light on the central puzzle surrounding scientific thought experiment, (...) which is how contemplation of an imaginary scenario can lead to new knowledge about contingent features of the natural world. (shrink)

This book offers a novel analysis of the widely-used but ill-understood technique of thought experiment. The author argues that the powers and limits of this methodology can be traced to the fact that when the contemplation of an imaginary scenario brings us to new knowledge, it does so by forcing us to make sense of exceptional cases.

I argue that thought experiments are a form of experimental reasoning similar to real experiments. They require the same ability to participate by following a narrative as real experiments do. Participation depends in turn on using what we already know to visualize, manipulate and understand what is unfamiliar or problematic. I defend the claim that visualization requires embodiment by an example which shows how tacit understanding of the properties of represented objects and relations enables us to work out how such (...) objects might behave in a postulated world. This knowledge is that of embodied agents. That thought experiments require embodied participation is what makes them experiments rather than arguments. Unlike real experiments, from which ordinary perception has been displaced by instrumentation, thought experiments still appeal to relatively unmediated common sense, even when their purpose is to criticize or subvert common sense notions. (shrink)

By carefully examining one of the most famous thought experiments in the history of science—that by which Galileo is said to have refuted the Aristotelian theory that heavier bodies fall faster than lighter ones—I attempt to show that thought experiments play a distinctive role in scientific inquiry. Reasoning about particular entities within the context of an imaginary scenario can lead to rationally justified concluusions that—given the same initial information—would not be rationally justifiable on the basis of a straightforward argument.

Still today it remains unclear whether Galileo ever climbed the leaning tower of Pisa in order to drop bodies from its top. Some believe that he established the principle of equal speeds for falling bodies by means of an ingenious thought experiment. However, the reconstruction of that thought experiment circulating in the philosophical literature is no more than a cartoon. In this paper I will tell the story of the thought processes behind the cartoon.Keywords: Galileo Galilei; Thought experiment; Falling bodies.

Proofs and Refutations is essential reading for all those interested in the methodology, the philosophy and the history of mathematics. Much of the book takes the form of a discussion between a teacher and his students. They propose various solutions to some mathematical problems and investigate the strengths and weaknesses of these solutions. Their discussion (which mirrors certain real developments in the history of mathematics) raises some philosophical problems and some problems about the nature of mathematical discovery or creativity. Imre (...) Lakatos is concerned throughout to combat the classical picture of mathematical development as a steady accumulation of established truths. He shows that mathematics grows instead through a richer, more dramatic process of the successive improvement of creative hypotheses by attempts to 'prove' them and by criticism of these attempts: the logic of proofs and refutations. (shrink)

In this book, Sorensen presents the first general theory of the thought experiment. He analyses a wide variety of thought experiments, ranging from aesthetics to zoology, and explores what thought experiments are, how they work, and what their positive and negative aspects are. Sorensen also sets his theory within an evolutionary framework and integrates recent advances in experimental psychology and the history of science.

Max Jammer's Concepts of Simultaneity presents a comprehensive, accessible account of the historical development of an important and controversial concept -- which played a critical role in initiating modern theoretical physics -- from the days of Egyptian hieroglyphs through to Einstein's work in 1905, and beyond. Beginning with the use of the concept of simultaneity in ancient Egypt and in the Bible, the study discusses its role in Greek and medieval philosophy as well as its significance in Newtonian physics and (...) in the ideas of Leibniz, Kant, and other classical philosophers. The central theme of Jammer's presentation is a critical analysis of the use of this concept by philosophers of science, like Poincaré, and its significant role in inaugurating modern theoretical physics in Einstein's special theory of relativity. Particular attention is paid to the philosophical problem of whether the notion of distant simultaneity presents a factual reality or only a hypothetical convention. The study concludes with an analysis of simultaneity's importance in general relativity and quantum mechanics. (shrink)

Thought experiments in science are merely picturesque argumentation. I support this view in various ways, including the claim that it follows from the fact that thought experiments can err but can still be used reliably. The view is defended against alternatives proposed by my cosymposiasts.

This essay attempts to demonstrate that it is doubtful if Galileo's famous thought experiment concerning falling bodies in his 'Dialogues Concerning Two New Sciences' (Galileo 1954: 61-64) actually does succeed in proving that Aristotle was wrong in claiming that "bodies of different weight […] move […] with different speeds which stand to one another in the same ratio as their weights," (Galileo 1954: 61). (Part I); and further that it is likewise doubtful that that argument does or even can establish (...) Galileo's own famous 'Law of Falling Bodies,' viz., that regardless of their weight all bodies fall with the same speed. (Part II). (shrink)