This paper is intended to be an interdisciplinary investigation of the status of proper names, although it takes linguistics as its point of departure. In this study I will define proper names in terms of the currently developing Radical Construction Grammar, as promoted by Croft (to appear). Starting from the referential and semantic functions of proper names, I discuss the opposing theses of the language philosophers John Searle and Saul Kripke, and then formulate my position that proper names are assigned an ad hoc referent in an ad hoc name-giving act, i.e. not on the basis of a concept or predication as with common nouns. This ad hoc assignment can be repeated several times, so numerous people can be called John. Proper names do not have asserted lexical meaning but do display presuppositional meanings of several kinds: categorical (basic level), associative senses (introduced either via the name-bearer or via the name-form) and grammatical meanings. Language specifically, this referential and semantic status is reflected in the occurrence of proper names in certain constructions. I thus claim that close (or 'restrictive') appositional patterns of the form [definite article + noun + noun], e.g. the poet Burns, are relevant to the definition of proper names in English and also to the categorical (often basic level) meaning of the name. From proper names we can also derive nouns that appear as a special kind of common noun, e.g. another John. From a methodological viewpoint it is imperative to distinguish here between (proprial) lexemes or lemmas in isolation (dictionary entries) and proprial lemmas in their different functions (prototypically: proper name, nonprototypically: common noun or other). To corroborate the above theses, I will adduce recent psycholinguistic and especially neurolinguistic evidence. The overall argument will be based mainly on material from Germanic languages, especially English, Dutch and German.