Another category of tricky cases is when the hypothetical involves impossibilities. It's possible to accidentally construct a hypothetical that makes an assumption that isn't valid in our universe. (I think these paradoxes were unknown before the 20th century, but there may be a math example.) These crop up frequently in modern physics.

Would Olbers' paradox qualify?

Olbers' paradox Basically, if the universe is of infinite size, then because an infinite number of concentric shells can be constructed centred on the earth. More distant shells have more stars, but the intensity of light we experience is reduced in accordance with the inverse square law. As these two effects cancel out, each shell should be of equal brightness, and so as there are an infinite number shells, the sky should by full of light. If the universe is not infinite, it would collapse due to gravity.

The wrong assumption is that universe is static (and an ignorance of relativity)