PEIRCE TO STRAWSON Logic contains individual variables and propositional functions: corresponding to this, Russell believed, the world contains particulars and universals In logic complex propositions are built up as truth-functions of simple propositions Similarly, Russell came to believe, there were in the world independent atomic facts corresponding to the simple propositions Atomic facts consisted either in the possession by a particular of a characteristic, or else in a relation between two or more particulars This theory of Russell’s acquired the name ‘logical atomism’ The development of the theory can be followed in the books that Russell wrote in the years leading up to the First World War: The Problems of Philosophy (1912), a lastingly popular introduction to the subject, and the more professional Our Knowledge of the External World of 1914 The most vivid presentation was in a series of lectures in London in 1918, ‘The Philosophy of Logical Atomism’, published much later in Logic and Knowledge (1956) Russell came to believe that every proposition that we can understand must be composed wholly of items with which we are acquainted ‘Acquaintance’ was his word for immediate presentation: we were acquainted, for instance, with our own sense-data, which were his equivalents of Hume’s impressions or Descartes’s thoughts But direct acquaintance was also possible with the universals that lay behind the predicates of a reformed logical language; so much of Russell’s early Platonism remained Acquaintance, however, was not possible with objects distant in space and time: we could not be acquainted with Queen Victoria or even with our own past sense-data The things that were not known by acquaintance were known by description; hence the importance of the theory of descriptions in the development of logical atomism Russell now applied the theory of descriptions not only to round squares and fictional objects but to many things that common sense would regard as perfectly real, such as Julius Caesar, tables, and cabbages These, he now maintained, were logical constructions out of sense-data In a sentence such as ‘Caesar crossed the Rubicon’, uttered in England now, we have a proposition in which there are no individual constituents with which we are acquainted In order to explain how we can understand the sentence, Russell analysed the names ‘Caesar’ and ‘Rubicon’ as definite descriptions which, spelt out in full, would not include any terms referring to the objects apparently named in the sentence 53