 A question that continues to dog fallacy theory is how we are to conceive of fallacies. There would be advantages to having a unified theory of fallacies. It would give us a systematic way of demarcating fallacies and other kinds of mistakes; it would give us a framework for justifying fallacy judgments, and it would give us a sense of the place of fallacies in our larger conceptual schemes. Some general definition of ‘fallacy’ is wanted but the desire is frustrated because there is disagreement about the identity of fallacies. Are they inferential, logical, epistemic or dialectical mistakes? Some authors insist that they are all of one kind: Biro and Siegel, for example, that they are epistemic, and Pragma-dialectics that they are dialectical. There are reasons to think that all fallacies do not easily fit into one category.