In philosophy, thought experiments are often used to imagine possible situations and logically examine what they say about a particular issue. In a thought experiment, certain details are assumed in order to deduce what the outcome of those circumstances would be.
More recently, some thought experiments have been used to handle problems of philosophy of mind and epistemology. Mary’s Room, for example, was intended to show that physicalism in philosophy of mind misses something, while the Brain in a Vat thought experiment is meant to provide an updated example of the epistemic scepticism.
Thought experiments have the advantage of allowing one to examine hypothetical situations and analyse their results. However, it is important when forming a thought experiment that one does not presuppose their conclusion, or rule out any possibilities, in creating the example — lest the experiment fail to demonstrate its point.