Suppose someone proposes an account of some concept A in conjunctive form:
- x is a case of A if and only if x is a case of A1 and of A2 and ... of An.
- Suppose we can come up with a case where it's merely a coincidence that x is a case of A1,A2,...,An. Am I confident that x is still a case of A then?
Consider for instance someone who offers a complicated account of knowledge:
- x knows p if and only if (i) x believes p; (ii) p is true; (iii) x is justified in believing p; (iv) some complicated further condition holds.
Most proposed accounts crumble under this challenge. Just about the only account I know that doesn't is:
- x commits adultery with y if and only if (i) x or y is married; (ii) x is not married to y; (iii) x and y have sex.