detach the "consequent" "⊦q" from the symbol string "⊦p, ⊦(p⊃q)" and not carry these symbols forward in an ever-lengthening string of symbols. The three traditional "laws" (principles) of thought: Russell goes on to assert other principles, of which the above logical principle is "only one". He asserts that "some of these must be granted before any argument or proof becomes possible. When some of them have been granted, others can be proved." Of these various "laws" he asserts that "for no very good reason, three of these principles have been singled out by tradition under the name of 'Laws of Thought'. And these he lists as follows: "(1) The law of identity: 'Whatever is, is.' (2) The law of contradiction: 'Nothing can both be and not be.' (3) The law of excluded middle: 'Everything must either be or not be.'" Rationale: Russell opines that "the name 'laws of thought' is ... misleading, for what is important is not the fact that we think in accordance with these laws, but the fact that things behave in accordance with them; in other words, the fact that when we think in accordance with them we think truly." But he rates this a "large question" and expands it in two following chapters where he begins with an investigation of the notion of "a priori" (innate, built-in) knowledge, and ultimately arrives at his acceptance of the Platonic "world of universals". In his investigation he comes back now and then to the three traditional laws of thought, singling out the law of contradiction in particular: "The conclusion that the law of contradiction is a law of thought is nevertheless erroneous ... [rather], the law of contradiction is about things, and not merely about thoughts ... a fact concerning the things in the world." His argument begins with the statement that the three traditional laws of thought are "samples of self-evident principles". For Russell the matter of "self-evident" merely introduces the larger question of how we derive our knowledge of the world. He cites the "historic controversy ... between the two schools called respectively 'empiricists' [ Locke, Berkeley, and Hume ] and 'rationalists' [ Descartes and Leibniz]" (these philosophers are his examples). Russell asserts that the rationalists "maintained that, in addition to what we know by experience, there are certain 'innate ideas' and 'innate principles', which we know independently of experience"; to eliminate the possibility of babies