Philosophy makes regular use of thought experiments — imagined scenarios designed to elicit intuitions whose pattern is then taken to bear on a philosophical question. The brain in a vat, the Chinese Room, the experience machine, the ship of Theseus: each is a thought experiment whose features the reader is invited to consider and whose consideration is supposed to reveal something. The practice has been continuous since at least Socrates and is, on its surface, uncontroversial; what philosophical question one would address without ever describing an example is not easy to specify.
The practice has, nevertheless, attracted criticism of a recurring kind. The first complaint is that the scenarios described are often so far from anything anyone has actually encountered that the intuitions they elicit may be unreliable — products of how the imagination handles unfamiliar cases, rather than guides to the underlying philosophical question. The second is that the readings of the intuitions are themselves contested: two philosophers who agree on the intuition the scenario elicits often disagree about what the intuition is supposed to show. Both complaints have force, and both are sometimes pressed in tones that mistake force for finality.
A more careful response neither rejects the practice nor defends every use of it. Thought experiments work best when the question they are meant to address is itself reasonably well posed, when the imagined scenario does not vary so wildly from familiar cases that the imagination is doing more of the work than the question deserves, and when the link between the elicited intuition and the philosophical conclusion is itself part of what is being argued for rather than smuggled in as obvious. Used in this disciplined way, thought experiments are neither the central method of philosophy nor a mere rhetorical device but a particular tool whose use, like that of any tool, can be done well or badly.
The dispute over thought experiments has, in this sense, been less about whether they should be used than about the standards their use should meet. The standards have proved harder to articulate than the most enthusiastic defenders of the practice sometimes suggest, and the criticisms have proved more useful than the most dismissive critics sometimes allow. Between the two extremes lies the actual practice: imperfect, indispensable, occasionally misleading, occasionally illuminating, and always requiring the kind of attention to its own conditions that careful philosophy has been trying to give it.
It can be inferred from the passage that a thought experiment in which the imagined scenario varies wildly from any familiar case would, on the careful response described in Paragraph 3, most likely be regarded as: