柏拉圖折衷了肖合說與約定說二派的說法，一方面指出語詞與事物之間有其固定的關係，本身並不隨意，而另一方面又指出語言也有其約定俗成的一面，本身與事物並無原初的統一。此外，語言有其工具性的一面，用以表達事物涵義。而語言文字是由人類中的「名稱製造者」所創造，並且按若干法則如指事、形聲、會意、轉注等法則來製造文字。語言既表達知識，它就在不同程度上指涉著「真」與「偽」。柏拉圖還主張知識先於語言，以及語言、意義、事物三分等說法，它們對後世都產生很深遠的影響，有待後世的語言學家來澄清。

　　　　　In his attempt to synthesize the differences between the Similarity Theory and the Convention Theory, Plato points out that even though language is conventional to a certain extent, there is still a union between the Word and the Reality which is by no means accidental. Language is instrumental and composed by human “name-makers” according to certain fixed laws. Language deals with the expression of truth and falsity at various degrees and at different levels. Plato's thesis of knowledge, as well as that of the tripartite division of language, meaning, and the thing signified, has had a profound influence on the philosophers of language in subsequent generations.