Begging the Question: A Brief Introduction

Arguments are sometimes said to be question-begging, or circular, and sometimes, with an added specification, viciously circular. An argument can also be said to beg the question, and so can the person employing the argument. This is supposed to be a defect of the argument, and the defect is often informally explained as that of assuming what has to be proven, or the point at stake. The argument or the person which is so defective can be said to be committing the fallacy of petitio principii. We can also say, for short, that the argument is a petitio. I will use “is question-begging”, “is (viciously) circular”, and “is a petitio” interchangeably here. This fallacy is in many ways of special relevance for philosophy.