ないことはない

ないことはない is a soft way to acknowledge that something is possible or that a negative statement isn't entirely true. It means “it's not that … is impossible,” or “there is a possibility that …,” often used to moderate a stronger claim or to be cautiously optimistic. It can soften a denial or create room for a positive outcome without overpromising. It commonly attaches to verbs in the negative form (V-ない) to express that not achieving the outcome is not necessarily the case, and to phrases that imply feasibility or likelihood in context.