following classification of illocutionary speech acts: assertives = speech acts that commit a speaker to the truth of the expressed proposition directives = speech acts that are to cause the hearer to take a particular action, e.g. requests, commands and advice commissives = speech acts that commit a speaker to some future action, e.g. promises and oaths expressives = speech acts that express on the speaker's attitudes and emotions towards the proposition, e.g. congratulations, excuses and thanks declarations = speech acts that change the reality in accord with the proposition of the declaration, e.g. baptisms, pronouncing someone guilty or pronouncing someone husband and wife The classification is intended to be exhaustive but the classes are not mutually exclusive: John Austin's well-known example "I bet you five pounds it will rain" is both directive and commissive. Illocutionary force Several speech act theorists, including Austin himself, make use of the notion of an illocutionary force. In Austin's original account, the notion remains rather unclear. Some followers of Austin, such as David Holdcroft, view illocutionary force as the property of an utterance to be made with the intention to perform a certain illocutionary act—rather than as the successful performance of the act (which is supposed to further require the appropriateness of certain circumstances). According to this conception, the utterance of "I bet you five pounds that it will rain" may well have an illocutionary force even if the addressee doesn't hear it. However, Bach and Harnish assume illocutionary force if, and only if this or that illocutionary act is actually (successfully) performed. According to this conception, the addressee must have heard and understood that the speaker intends to make a bet with them in order for the utterance to have 'illocutionary force'. If we adopt the notion of illocutionary force as an aspect of meaning, then it appears that the (intended) 'force' of certain sentences, or utterances, is not quite obvious. If someone says, "It sure is cold in here", there are several different illocutionary acts that might be aimed at by the utterance. The utterer might intend to describe the room, in which case the illocutionary force would be that of 'describing'. But she might also intend to criticise someone who should have kept the room warm. Or it might be meant as a request to someone to close the window. These forces may be interrelated: it may be by way of