 This invited the thought that other philosophical puzzles might dissolve if we properly understood the logical forms of our claims.  Ludwig Wittgenstein  argued, in his influential Tractatus Logico-Philosophicus, that: (i) the very possibility of meaningful sentences, which can be true or false depending on how the world is, requires propositions with structures of the sort that Frege and Russell were getting at; (ii) all propositions are logical compounds of—and thus analyzable into—atomic propositions that are inferentially independent of one another; though (iii) even simple natural language sentences may correspond to very complex propositions; and (iv) the right analyses would, given a little reflection, reveal all philosophical puzzles as confusions about how language is related to the world. Wittgenstein later noted that examples like ‘This is red’ and ‘This is yellow’ present difficulties for his earlier view. (If the expressed propositions are unanalyzable, and thus logically independent, each should be compatible with the other; but at least so far, no one has provided a plausible analysis that accounts for the apparent impeccability of ‘This is red, so this is not yellow’. This raises questions about whether all inferential security is due to logical form.) And in any case, Russell did not endorse (iv). But he did say, for reasons related to certain epistemological puzzles, that (a) we are directly acquainted with the constituents of those propositions into which every proposition (that we can grasp) can be analyzed; (b) at least typically, we are not directly acquainted with the mind-independent bearers of proper names; and so (c) the things we typically refer to with names are not constituents of basic propositions.