This chapter considers the relations of knowledge to objectivity, certainty, intuition, deduction, and rigour. It argues that knowledge cannot be objective in the sense of being totally independent of any subject, but only in the sense of being as independent as possible of any particular human subject; that knowledge cannot be absolutely certain, since it can only be plausible; that knowledge is not obtained by intuition, not even fallible intuition; that knowledge cannot be obtained merely by deduction, but requires non-deductive reasoning; and that knowledge cannot be obtained by sticking to an abstract ideal of rigour, since what is important is not rigour but fruitfulness, hence the concept of rigour is better replaced with that of fruitfulness.