 The basic idea of this Platonic atomism seems to be the following: Knowledge consists in standing in an immediate relation to an independent individual object (assumption b). This immediate relation to individual objects is best known under Russell’s term “acquaintance”. If, by stipulation, knowledge is ultimately knowledge “by acquaintance”, then knowledge is restricted to knowledge of individual objects. Knowledge basically is knowledge of something or non-propositional knowledge. However, although this rather frugal conception of knowledge might be sufficient to give an account of the possibility of non-propositional knowledge, it is not that easy to see how such a conception can give a sensible explanation of propositional knowledge, i.e., of knowledge that something is so-and-so. Moore and Russell seem to have been acutely aware of this difficulty as is documented in their very explicit efforts to avoid it. It might have been their different reactions to this difficulty which in the years to come led them to proceed on diverging routes in philosophy. As is easy to imagine, there are two obvious reactions to the problem of propositional knowledge provided that assumption (b) is agreed upon. The first is to claim that propositions (Moore prefers the term “judgment” in this context) are individual objects with which the subject is acquainted (if he or she claims to know that something is so-and-so). The second is to broaden the concept of knowledge by not restricting knowledge to knowledge by acquaintance but to allow for other forms of knowledge as well. The first reaction apparently was the reaction of Moore and is formulated most prominently in his early piece “The Nature of Judgment” (1899), while the second can be attributed to Russell and is documented most vividly in his The Problems of Philosophy.