Complex question, trick question, multiple question or plurium interrogationum (Latin, "of many questions") is a question that has a presupposition that is complex. The presupposition is a proposition that is presumed to be acceptable to the respondent when the question is asked. The respondent becomes committed to this proposition when he gives any direct answer. The presupposition is called "complex" because it is a conjunctive proposition, a disjunctive proposition, or a conditional proposition. It could also be another type of proposition that contains some logical connective in a way that makes it have several parts that are component propositions.
Implication by question 
One form of misleading discourse involves presupposing and implying something without stating it explicitly, by phrasing it as a question. For example, the question "Does Mr. Jones have a brother in the army?" does not claim that he does, but implies that there must be at least some indication that he does, or the question would not need to be asked. The person asking the question is thus protected from accusations of making false claims, but still manages to make the implication in the form of a hidden compound question. The fallacy isn't in the question itself, but rather in the listener's assumption that the question would not have been asked without some evidence to support the supposition. This example seems harmless, but consider this one: "Does Mr. Jones have a brother in jail?"
In order to have the desired effect, the question must imply something uncommon enough not to be asked without some evidence to the fact. For example, the question "Does Mr. Jones have a brother?" would not cause the listener to think there must be some evidence that he does, since this form of general question is frequently asked with no foreknowledge of the answer.
Complex question fallacy 
The complex question fallacy, or many questions fallacy, is context dependent; a presupposition by itself doesn't have to be a fallacy. It is committed when someone asks a question that presupposes something that has not been proven or accepted by all the people involved. For example, "Is Mary wearing a blue or a red dress?" is fallacious because it artificially restricts the possible responses to a blue or red dress. If the person being questioned wouldn't necessarily consent to those constraints, the question is fallacious.
Hence we can distinguish between:
- legitimately complex questions (not a fallacy): A question that assumes something that the hearer would readily agree to. For example, "Who is the monarch of the United Kingdom?" assumes that there is a place called the United Kingdom and that it has a monarch, both true.
- illegitimately complex question: On the other hand, "Who is the King of France?" would commit the complex question fallacy because while it assumes there is a place called France (true), it also assumes France currently has a king (false). But since this answering the question does not seem to incriminate or otherwise embarrass the speaker, it is complex but not really a loaded question.
When a complex question contains controversial presuppositions (often with loaded language – having an unspoken and often emotive implication), it is known as a loaded question. For example, a classic loaded question, containing incriminating assumptions that the questioned persons seem to admit to if they answer the questions instead of challenging them, is "Have you stopped beating your spouse?" If the person questioned answers, "Yes", then that implies that they have beaten their spouse before. A loaded question may be asked to trick the respondent into admitting something that the questioner believes to be true, and which may in fact be true. So the previous question is "loaded," whether or not the respondent has actually beaten their spouse — and if the respondent answers anything other than "yes" or "no" in an attempt to deny having beaten their spouse, the questioner can accuse them of "trying to dodge the question". The very same question may be loaded in one context, but not in the other. For example, the previous question would not be loaded if it was asked during a trial in which the defendant has already admitted to beating their spouse.
Similar questions and fallacies 
Closely connected with [petitio principii] is the fallacy of the Complex Question. By a complex question, in the broadest meaning of that term, is meant one that suggests its own answer. Any question, for instance, that forces us to select, and assert in our answer to it, one of the elements of the question itself, while some other possibility is really open, is complex in the sense in which that term is here employed. If, for example, one were to ask whether you were going to New York or London, or if your favourite colour were red or blue, or if you had given up a particular bad habit, he would be guilty of the fallacy of the complex question, if, in each case, the alternatives, as a matter of fact, were more numerous than, or were in any way different from, those stated in the question. Any leading question which complicates an issue by over simplification is fallacious for the same reason… In the petitio principii an assumption with respect to the subject-matter of an argument functions as a premise, in the complex question it is a similar assumption that shuts out some of the material possibilities of a situation and confines an issue within too narrow limits. As in the former case, so here, the only way of meeting the difficulty is to raise the previous question, that is, to call the assumption which lies back of the fallacy into question.—Arthur Ernest Davies, "Fallacies" in A Text-Book of Logic
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