 But the kind of necessity that concerns us here is epistemic necessity, the necessity of things that must be true given what we know. For example, it is epistemically necessary for you that the author of this sentence is human. If you didn’t know that already (maybe you hadn’t considered the question), it had to be true given other things you did know: that humans are the only beings on Earth capable of constructing coherent surveys of formal epistemology, and that this is such a survey (I hope).