Many philosophy problems involve imagining hypothetical scenarios. At times there has been significant debate over the validity of this.
At times there has been significant debate on Less Wrong about the relevance or value in discussing hypotheticals that would never occur in the real world. In The Least Convenient Possible World, Scott Alexander suggests that ignoring hypotheticals often means that you are technically correct at the cost "missing the point and losing a valuable effort to examine the nature of morality". He suggests that considering about the least convenient world is often vital for allowing us to discover our true motivations and often leaves us too much "wiggle room".
Hypotheticals are essentially the same as counterfactuals, although a) the term counterfactual is preferred when imagining someone making different decisions b) technically the factual isn't a counterfactual, but it is very common to say something like "iterate over all the counterfactuals and pick the one with the highest utility" where we treat the factual as a counterfactual.