The main objective is an interpretation of the island parody, in particular a logical reconstruction of the parodying argument that stays close to the text. The parodied reasoning is identified as the proof in the second chapter of the Proslogion, more specifically, this proof as it is represented by Gaunilo in the first chapter of his Liber pro insipiente. The second task is a detailed comparison between parodied and parodying argument as well as an account of their common structure. The (...) third objective is a tentative characterization of the nature and function of parodies of arguments. It seems that parodying does not add new pertinent points of view to the usual criticism of an argument. (shrink)