or bad. In philosophy, fallacies are usually seen as a form of bad argument and are discussed as such in this article. Another conception, more common in non-scholarly discourse, sees fallacies not as arguments but rather as false yet popular beliefs. Traditional account Informal fallacies are a form of incorrect argument in natural language. An argument is a series of propositions, called the premises, together with one more proposition, called the conclusion. The premises in correct arguments offer either deductive or defeasible support for the conclusion. The source of the error in incorrect arguments can be in the argument's form, content or context. If the error is only due to the form, it is considered a formal fallacy. Informal fallacies may also include formal errors but they primarily involve errors on the level of content and context. Informal fallacies are expressed in natural language. This brings with it various difficulties not faced when studying formal fallacies, like ambiguous terms, vague expressions or the premises being assumed implicitly rather than stated explicitly. Traditionally, a great number of informal fallacies have been listed, including the fallacy of equivocation, the fallacy of amphiboly, the fallacies of composition and division, the false dilemma, the fallacy of begging the question, the ad hominem fallacy or the appeal to ignorance. The traditional approach tries to account for these fallacies using the concepts and theses discussed in this section. Arguments and fallacies Only arguments can constitute a fallacy. Various erroneous expressions do not count as fallacies because no argument was made, e.g. because no reasons were cited or no assertion was made. The core idea of arguments is that the premises support the conclusion or that the conclusion follows from the premises. Deductively valid arguments offer the strongest form of support: for them, it is impossible for the conclusion to be false if all the premises are true. The premises in non-deductive arguments offer a certain degree of support for their conclusion but they are defeasible: it is possible for all the premises to be true and the conclusion to be false. Defeasible arguments may still be rationally compelling despite being fallible. So they do not automatically constitute fallacies. The premises of an argument may be seen as the foundation on which the conclusion is built. According to this analogy, two things can go wrong and turn an argument into a fallacy. It could be that the