 However, the view that illocutionary acts types are conventional in this sense has met with much opposition. Strawson (1964: 153–154) objected early on that ordinary illocutionary acts can be performed without relying on any convention to identify the force, for instance when using a declarative sentence like “The ice over there is very thin” for a warning. This kind of criticism, directed against Dummett, has later been reinforced by Robert J. Stainton (1996, 2006), stressing that in appropriate contexts, sub-sentential phrases like “John’s father” (pointing at a man) or “very fast” (looking at a car) can be used to make assertions, and gives linguistic arguments why not all such uses can be treated as cases of ellipsis (that is, as cases of leaving out parts of a well-formed sentence that speaker and hearer tacitly aware of). If Strawson and Stainton are right, convention isn’t necessary for making assertions.