[The following is a heavily edited version of a section from my MA dissertation. It is not meant therefore to stand alone in terms of motivation or argument, but presents some interesting ideas nonetheless. The background is that there is a potential problem raised by the persuasive power yet eminent fallibility of thought-experiments. This section notes that this problem does not exist for one particular way of persuading through thought-experiments]
Thought-experiments are often used merely to illustrate, or to teach the inner workings of, a theory. They provide a route into understanding otherwise opaque theory (Klassen, 2006); accordingly their place in education—science especially—has been emphasised by many.
One may not understand Utilitarianism expressed thus: to do right is to maximise pleasure and minimise pain. A teacher may provide one with a better grasp using a thought-experiment.
Imagine it is Right to maximise pleasure and minimise pain. An old blind woman is about to step out in front of a lorry. Should you stop and help, if
Condition A: You are on your way to the shops?
Condition B: You are a fire-fighter on your way to put out a blaze in an old people’s home?
The reaction, ‘Oh I see, that’s the sort of decision I would have to make,’ allows one to better understand Utilitarianism, and in turn be more likely to be persuaded as to its merits (or indeed persuaded as to its falsity).[1]
Teachers often use thought-experiments in this manner. Whilst they may not wish to persuade students as to the truth of some theory, it is often in their interest to portray the theory in a favourable light. Teachers wish to encourage students to recognise that a theory is worthy of consideration, to make salient its merits. The fact that this use of thought-experiment may aid persuasive efforts does not seem to generate a problem.
It is nonetheless noteworthy that a pedagogical or illustrative use of a thought-experiment is not necessarily an impartial presentation. Without the evenness of hand expected a teacher may raise the probability that she, to whom the illustration is addressed, will be persuaded in any one direction. Rather, an illustrative/pedagogical use of a thought-experiment is characterised by being foremost a mere demonstration of the features of theory—regardless of any bias in the presentation. This use exists also in science. One might have difficulty understanding relativity of simultaneity, until one considers the following imaginary example. This is based on an example in (Magueijo, 2003)
Einstein has a dream: a long line of cows is electrocuted by current passing along a single straight wire. One observer notes each cow jump back in sequence, as the current flows away from him. Another, stood at the other end of the wire, observes each cow jump back simultaneously. (The speed of light is assumed to be equal to that of the current in the wire).
The thought-experiment demonstrates that the theory has some explanatory power; that it is worthy of consideration and acceptance. It is not used to establish the conclusion per se. Rather, it is an exposition, which may contribute to some party’s persuasion.
To conclude, thought-experiments may aid in persuasion whilst used in purely pedagogical or illustrative manners. However, beyond worries about partial presentation in situations in which impartiality is presumed, there is little motivation for worrying about thought-experiments as a methodological resource when used in this manner. We have the resources to analyse whether something has gone wrong in the portrayal of a theory and should be able to avoid any problems.
[1] For, better understanding of a theory may motivate its rejection. However, given one cannot accept a theory which one doesn’t think one understands, I maintain that (in a trivial sense) understanding a theory will raise the probability one will accept it. None-the-less, the motivation of rejection is still persuasion, albeit not in the direction that the persuader desired.