Impossibility

Impossibility, in terms of modality, refers to a situation or scenario that cannot happen or is not achievable under any circumstances. It's distinct from possibility, which means something can happen, and necessity, which means it must happen. For example, it is impossible for a square to be a circle simultaneously because they are fundamentally different shapes. In philosophy and logic, discussing impossibility helps us understand the boundaries of what is feasible and what remains firmly outside the realm of reality.