 It is a peculiar thing—the result of estimate—and we call it by a peculiar name, opinion. For it, taken in its strict and proper sense, we can use no term that belongs to knowing. For the opinion that A is B is founded on evidence we know to be insufficient, whereas it is of the very nature of knowledge not to make its statements at all on grounds recognized to be insufficient, nor to come to any decision except that the grounds are insufficient; for it is here that in the knowing activity we stop. (SI, 99–100)