In most language use in the world, there are three main types of sentences. They are declarative, interrogative, and imperative. Each of these sentence types has a different illocutionary force. Declarative for instance, has the asserting illocutionary force, while interrogative is for asking/questioning, and imperative is for ordering/requesting. These are the examples of the sentences types:
[1.8 a]. I am a man. (declarative/stating)
[1.8 b]. I am a man? (interrogative/asking)
[1.8 c]. Be a man! (Imperative/ordering)
[1.8 d]. I (hereby) order you to be a man. (imperative/ordering)
In these sentences it is possible to see the distinctions of the sentence types of declarative, interrogative, and imperative. However, other forms of sentences are sometimes used for an intention or illocutionary force other than the one that is duly intended in using the sentence types.
Searle (1979) introduced the idea of indirect illocutionary act which also known as indirect speech act. This is speaker's act of communicating with hearer more than what is actually said. It relies on the knowledgeable background information about the conversation shared by both speaker and hearer. In other words, indirect speech acts is the act of conducting an illocutionary act indirectly. For example, one might say "Could you open the door?", thereby asking the hearer if he/she could open the door. Nevertheless, this interrogative sentence also requests the hearer to open the window indirectly. Searle (1979:33) made a point by using this example:
[1.9] A says to a friend say: "Let's go to the movie tonight."
the friend B answers: "I have to study for an exam."
In this example [1.9] it shows that B (second utterance) doesn't answered A's question, but instead he/she utter a declarative sentence and asserts that he/she needs to study for an exam. This utterance is in fact, a form of an indirect speech act, and an act of refusal. As quoted from Mey (2001), Searle proofs that the second utterance in [1.9] is an act of refusing A's suggestion to the movie using 10 steps:
Step 1: A has made a suggestion (to go to the movies) and B has uttered a statement (about having to study for exam). These are facts that happen between both speaker.(Factual background)
Step 2: A assumes that B to be cooperative in the conversation and expect an answer that is more relevant in fulfillment of the Cooperative principle's maxim of relevance.(Cooperative principle)
Step 3: Relevant answers in this case should be among the following: acceptance(yes, sure), rejection(no, thanks), counter-suggestion(Why don't we make it tomorrow?), suggestion for further discussion(That entirely depends on what's on), etc.(Theory of speech act)
Step 4: No relevant answer in step 3 matches the answer made by B. so it is possible to say that it is not one of these. (Taken from step 1 to 3). (Inference of step 3)
Step 5: Therefore, it is possible to assume that B means more (or something entirely different), assuming that his answer is relevant, his illocutionary must differ from the literal one. Step 2 and 4 is the most important step in this argument, as Searle says "unless we can distinguish the primary from the literal, there is no way of making sense of indirect speech act"(Inference from step 2 and 4)
Step 6: Studying for exam usually takes a lot of time which is precious while going to a movie will also take some precious times. This is something that a student cannot afford to lose, especially in pre-exam condition. (Factual background information)
Step 7: Hence, it seems that B cannot do both studying for the exam and going to the movie.(inferring step 6)
Step 8: Preparatory condition of a proposal are the ability and willingness to do the proposed act.(Theory of speech act)
Step 9: Therefore, it is possible to assume that B having to do something else, cannot accept the proposal to go to the movie. (Inferring from step 1, 7, and 8)
Step 10: Therefore, his utterance about having to study for exam is probably a form of rejection of A's proposal. (Inferring step 5 and 9)
Indirect speech acts theory is closely related to the theory of Grice's maxim of cooperative principles, which will be explained in subchapter 2.2.1 Incongruity theory. As mentioned by Huang (2007), Searle uses Cooperative principles to find inferences to identify indirect speech acts. He also mentioned that Searle has developed three approaches to analyze whether an utterance is a direct or indirect speech act. First, by assuming dual illocutionary act. The first one is literal or direct and the other one is non-literal or indirect. Second, find the relevant felicity conditions. The third step is as mentioned above, using the cooperative principles.
On the other hand, if the illocutionary force and the sentence type is matched directly, it is called a direct speech act. Like in example [1.8.d], in that sentence the speaker clearly says his/her intention which is ordering.