A question is a linguistic expression used to make a request for information, or the request made using such an expression. The information requested is provided in the form of an answer.
Questions have developed a range of uses that go beyond the simple eliciting of information from another party. Rhetorical questions, for example, are used to make a point, and are not expected to be answered. Many languages have special grammatical forms for questions (for example, in the English sentence "Are you happy?", the inversion of the subject you and the verb are shows it to be a question rather than a statement). However, questions can also be asked without using these interrogative grammatical structures – for example one may use an imperative, as in "Tell me your name".
The principal use of questions is to elicit information from the person being addressed by indicating the information which the speaker (or writer) desires. However, questions can also be used for a number of other purposes. Questions may be asked for the purpose of testing someone's knowledge, as in a quiz or examination. Raising a question may guide the questioner along an avenue of research (see Socratic method).
A research question is an interrogative statement that manifests the objective or line of scholarly or scientific inquiry designed to addresses a specific gap in knowledge. Research questions are expressed in a language that is appropriate for the academic community that has the greatest interest in answers that would address said gap. These interrogative statements serve as launching points for the academic pursuit of new knowledge by directing and delimiting an investigation of a topic, a set of studies, or an entire program of research.
A rhetorical question is asked to make a point, and does not expect an answer (often the answer is implied or obvious). Some questions are used principally as polite requests, as with "Would you pass the salt?"
Pre-suppositional or loaded questions, such as "Have you stopped beating your wife?" may be used as a joke or to embarrass an audience, because any answer a person could give would imply more information than he was willing to affirm.
Questions can also be used as titles of works of literature, art and scholarship. Examples include Leo Tolstoy's short story How Much Land Does a Man Need?, the painting And When Did You Last See Your Father?, the movie What About Bob?, and the academic work Who Asked the First Question?
Various categorizations of questions have been proposed. With regard to research projects, one system distinguishes:
For the purpose of surveys, one type of question asked is the closed-ended (also closed or dichotomous) question, usually requiring a yes/no answer or the choice of an option(s) from a list (see also multiple choice). There are also nominal questions, designed to inquire about a level of quantitative measure, usually making connections between a number and a concept (as in "1 = Moderate; 2 = Severe; 3 = ..."). Open-ended or open questions give the respondent greater freedom to provide information or opinions on a topic. (The distinction between closed and open questions is applied in a variety of other contexts too, such as job interviewing.) Surveys also often contain qualifying questions (also called filter questions or contingency questions), which serve to determine whether the respondent needs to continue on to answer subsequent questions.
Some types of questions that may be used in an educational context are listed in Bloom's Taxonomy of educational objectives. These include questions designed to test and promote:
McKenzie's "Questioning Toolkit" lists 17 types of questions, and suggests that thinkers need to orchestrate and combine these types. Examples of these question types include the irreverent question, the apparently irrelevant question, the hypothetical question and the unanswerable question. Questions can also be infelicitous, being based on incorrect and illogical premises (e.g. "Why do cats have green wings?").
Strategic studies also took into consideration the questioning process. In Humint (Human Intelligence), a taxonomy of questions includes:
By grammatical form
Questions that ask whether or not some statement is true are called yes–no questions (or polar questions), since they can in principle be answered by a "yes" or "no" (or similar words or expressions in other languages). Examples include "Do you take sugar?", "Should they be believed?" and "Am I the loneliest person in the world?"
A type of question that is similar in form to a yes–no question, but is not intended to be answered with a "yes" or "no", is the alternative question (or choice question). This presents two or more alternative answers, as in "Do you want fish or lamb?", or "Are you supporting England, Ireland or Wales?" The expected response is one of the alternatives, or some other indication such as "both" or "neither" (questionnaire forms sometimes contain an option "none of the above" or similar for such questions). Because of their similarity in form to yes–no questions, they may sometimes be answered "yes" or "no", possibly humorously or as a result of misunderstanding.
The other main type of question (other than yes–no questions) is those called wh-questions (or non-polar questions). These use interrogative words (wh-words) such as when, which, who, how, etc. to specify the information that is desired. (In some languages the formation of such questions may involve wh-movement – see the section below for grammatical description.) The name derives from the fact that most of the English interrogative words (with the exception of how) begin with the letters wh. These are the types of question sometimes referred to in journalism and other investigative contexts as the Five Ws.
Tag questions are a grammatical structure in which a declarative statement or an imperative is turned into a question by adding an interrogative fragment (the "tag"), such as right in "You remembered the eggs, right?", or isn't it in "It's cold today, isn't it?" Tag questions may or may not be answerable with a yes or no.
As well as direct questions (such as Where are my keys?), there also exist indirect questions (also called interrogative content clauses), such as where my keys are. These are used as subordinate clauses in sentences such as "I wonder where my keys are" and "Ask him where my keys are." Indirect questions do not necessarily follow the same rules of grammar as direct questions. For example, in English and some other languages, indirect questions are formed without inversion of subject and verb (compare the word order in "where are they?" and "(I wonder) where they are"). Indirect questions may also be subject to the changes of tense and other changes that apply generally to indirect speech.
Languages may use both syntax and prosody to distinguish interrogative sentences (which pose questions) from declarative sentences (which state propositions). Syntax refers to grammatical changes, such as moving words around or adding question words; prosody refers here to changes in intonation while speaking.
In English, German, French and various other languages, questions are marked by a distinct word order featuring inversion – the subject is placed after the verb rather than before it: "You are cold" becomes "Are you cold?" However, English allows such inversion only with a particular class of verbs (called auxiliary or special verbs), and thus sometimes requires the addition of an auxiliary do, does or did before inversion can take place ("He sings" → "Does he sing?") – for details see do-support.
In some languages, yes–no questions are marked by an interrogative particle, such as the Japanese か ka, Mandarin 吗 ma and Polish czy. Also, in languages generally, wh-questions are marked by an interrogative word (wh-word) such as what, where or how. In languages such as English this word generally moves to the front of the sentence (wh-fronting), and subject–verb inversion occurs as in yes–no questions, but in some other languages these changes in word order are not necessary (e.g. Mandarin 你要什么？ nǐ yào shénme, meaning "what do you want?" is literally "you want what?").
Intonation patterns characteristic of questions often involve a raised pitch near the end of the sentence. In English this occurs especially for yes–no questions; it may also be used for sentences that do not have the grammatical form of questions, but are nonetheless intended to elicit information (declarative questions), as in "You're not using this?"
In languages written in Latin, Cyrillic or certain other scripts, a question mark at the end of a sentence identifies questions in writing. (In Spanish an additional inverted mark is placed at the beginning: ¿Cómo está usted? "How are you?") As with intonation, this feature is not restricted to sentences having the grammatical form of questions – it may also indicate a sentence's pragmatic function.
The most typical response to a question is an answer that provides the information indicated as being sought by the questioner. This may range from a simple yes or no (in the case of yes–no questions) to a more complex or detailed answer. (An answer may be correct or incorrect, depending on whether the information it presents is true or false.) An indication of inability or unwillingness to provide an answer is the other response to a question.
"Negative questions" are interrogative sentences which contain negation in their phrasing, such as "Shouldn't you be working?" These can have different ways of expressing affirmation and denial from the standard form of question, and they can be confusing, since it is sometimes unclear whether the answer should be the opposite of the answer to the non-negated question. For example, if one does not have a passport, both "Do you have a passport?" and "Don't you have a passport?" are properly answered with "No", despite apparently asking opposite questions. The Japanese and Korean languages avoid this ambiguity. Answering "No" to the second of these in Japanese or Korean would mean, "I do have a passport".
A similar ambiguous question in English is "Do you mind if...?" The responder may reply unambiguously "Yes, I do mind," if they do mind, or "No, I don't mind," if they don't, but a simple "No" or "Yes" answer can lead to confusion, as a single "No" can seem like a "Yes, I do mind" (as in "No, please don't do that"), and a "Yes" can seem like a "No, I don't mind" (as in "Yes, go ahead"). An easy way to bypass this confusion would be to ask a non-negative question, such as "Is it all right with you if...?"
Some languages have different particles (for example the French "si", the German "doch" or the Danish and Norwegian "jo") to answer negative questions (or negative statements) in an affirmative way; they provide a means to express contradiction.
More information on these issues can be found in the articles Yes–no question, Yes and no, and Answer ellipsis.
Questions are used from the most elementary stage of learning to original research. In the scientific method, a question often forms the basis of the investigation and can be considered a transition between the observation and hypothesis stages. Students of all ages use questions in their learning of topics, and the skill of having learners creating "investigatable" questions is a central part of inquiry education. The Socratic method of questioning student responses may be used by a teacher to lead the student towards the truth without direct instruction, and also helps students to form logical conclusions.
A widespread and accepted use of questions in an educational context is the assessment of students' knowledge through exams.
The philosophical questions are conceptual, not factual questions. There are questions that are not fully answered by any other. Philosophy deals with questions that arise when people reflect on their lives and their world. Some philosophical questions are practical: for example, "Is euthanasia justifiable?", "Does the state have the right to censor pornography or restrict tobacco advertising?", "To what extent are Māori and Pākehā today responsible for decisions made by their ancestors?"
Other philosophical questions are more theoretical, although they often arise through thinking about practical issues. The questions just listed, for example, may prompt more general philosophical questions about the circumstances under which it may be morally justifiable to take a life, or about the extent to which the state may restrict the liberty of the individual. Some "classic" questions of philosophy are speculative and theoretical and concern the nature of knowledge, reality and human existence: for example, "What, if anything, can be known with certainty?", "Is the mind essentially non-physical?", "Are values absolute or relative?", "Does the universe need explanation in terms of a Supreme Intelligence?", "What, if anything, is the meaning or purpose of human existence?" Finally, the philosophical questions are typically about conceptual issues; they are often questions about our concepts and the relation between our concepts and the world they represent. Every question implies a statement and every statement implies a question.
Enculturated apes Kanzi, Washoe, Sarah and a few others who underwent extensive language training programs (with the use of gestures and other visual forms of communications) successfully learned to answer quite complex questions and requests (including question words "who" what", "where"), although so far they failed to learn how to ask questions themselves. For example, David and Anne Premack wrote: "Though she [Sarah] understood the question, she did not herself ask any questions — unlike the child who asks interminable questions, such as What that? Who making noise? When Daddy come home? Me go Granny's house? Where puppy? Sarah never delayed the departure of her trainer after her lessons by asking where the trainer was going, when she was returning, or anything else". The ability to ask questions is often assessed in relation to comprehension of syntactic structures. It is widely accepted, that the first questions are asked by humans during their early infancy, at the pre-syntactic, one word stage of language development, with the use of question intonation.