When faced with a problem, some people "solve for no" (think of obstacles/reasons it can't be done) and some "solve for yes" (think of ways to do it).
While it's true that some folks default to one or the other approach regardless of the problem, I've found one of the best ways to tell whether someone actually wants to do something (and more accurate than what they claim to want), is whether they solve for no or solve for yes.
@kyle ...so problem avoidance. ;-)
Can you have a solution (solve) without a problem? Note your example wishes require a reason, and both imply problems.
@lwriemen The principle extends even past problems, I just didn't have a better word to describe being faced with a proposal in general. For instance, it applies to someone who might say "I want to exercise more" or "I want to read more" and then when you ask them how it's going, they explain all of the reasons why they can't (solve for no). In general (exceptions exist) when someone actually wants to do something, their energy gets devoted to finding ways to do it, than not to do it.