In his 1903 monograph Principles of Mathematics Bertrand Russell formulated a theory which interpreted a proposition expressed by a sentence as a unitary bond of referents (meanings) of its parts. In the paper I argue that the problem he faced in his attempt to define the unity of proposition is a special case of a wider philosophical problem of the relation between language and the world. Mentioned for the first time by Plato in Parmenides and then repeated by Aristotle in Metaphysics, infinite regress formulated as ʻthe third man argument’ presented a problem for Francis Bradley, Bertrand Russell and Gottlob Frege. It was reformulated in syntactic terms by Hans Reichenbach and used by Donald Davidson as an argument against referential semantics. The conclusion of the paper is as follows: ʻthe third man argument’ is a result of projecting syntactic structures of language on metaphysically conceived referential semantics. It does not undermine ontology conceived as an investigation of possible beings.