这词儿中文不太好翻译，也许可以用「平凡」代替。「空虚的真/虚真」有种中二的感觉。
In logic and mathematics, when a statement or proposition is considered true simply because there are no instances that make it false due to an empty domain of discourse, it is said to be vacuously true. This situation arises when the condition being evaluated cannot be satisfied because there are no elements in the domain under consideration.
For instance, consider the proposition “All unicorns can fly.” In reality, there are no unicorns, so the proposition is vacuously true because there are no instances of unicorns that fail to meet the condition of flying. Similarly, if you have a universally qualified proposition like “For all x in the empty set, P(x) is true,” where the domain (empty set) contains no elements to evaluate, the proposition is considered true by default, regardless of the truth value of P(x).
(from AI)