The simplest form of a dilemma is an argument of the form: ‘If p then q, if not-p then q, so in any event q.’ More complex forms were traditionally distinguished. A constructive dilemma is of the form: ‘If p then r, if q then r, but either p or q, so r.’ A destructive dilemma is of the form: ‘If p then q, and if p then r, but either not-q or not-r, so not-p.’ The two conditional premises of a dilemma are called its horns. Escaping between the horns of the dilemma is denying the disjunction ‘p or q’; taking it by the horns is denying one of the conditionals. The notion generalizes to trilemmas, in which there are three horns (see, for example, Bayle’s trilemma). For other dilemmas see Euthyphro dilemma, moral dilemmas, prisoners’ dilemma.