This research is concerned with aspects of the long running debate about 'What is History?' It focuses on the recent postmodern sceptical challenge to traditional historiography by Keith Jenkins, Alun Munslow and Beverley Southgate and the rebuttal of that challenge by empirical historians such as Richard Evans, Arthur Marwick and Perez Zagorin. The problem with this controversy is that its grounds are narrow. The exchanges have polarised around a particular postmodern treatment of scepticism, arguing for and against whether present empirical methods are capable of providing adequate explanations of the past. What I hope to contribute to this debate is a broadening of its frame of reference to a more general question of how historians might respond to wider questions about the nature of knowledge in the face of apparent epistemological uncertainty. I am using the concept of 'aporia' to express this sense of ultimate uncertainty about the possibility of true, objective, knowledge. The study takes seriously the scepticism of both positions - empirical as well as postmodern - and it does this in two ways. First, it places contemporary empiricism into an historical context that includes the empiricism of sophists and pyrrhonists of the ancient world, of Hume in the enlightenment, of Comte and J. S. Mill in the nineteenth century and more recently the radical empiricism of American pragmatism. This part of the study concludes that empiricism has long been associated with philosophical scepticism to the extent that it can be regarded as a legitimate and traditional, if sometimes unselfconscious, response to aporia. Thus scepticism can be thought to be integral to this approach to knowledge, not corrosive of it. Attempts by contemporary empirical historians to overcome the postmodern challenge by arguing for objective certainty in history, are therefore unnecessary and inappropriate. Similarly, postmodern critiques of empirical historiography that simply direct attention to the existence of aporia, rather than discuss forms of response to it, demonstrate a weakness in their analysis of empiricism. Second, the study contextualises this controversy within a broader debate about how other groups of historians are currently responding to issues of aporia. It notes how some contemporary Marxist historians, for example Patrick Joyce, are opening a fruitful dialogue with poststructural linguistic theorists, developing interpretative concepts of a cultural kind that are thought to function more flexibly than traditional ones. Overall the research concludes that the negativity of the postmodern critique, which seems to suffuse much discussion of historical theory and methods, is not a necessary outcome of such explorations. A broader view, taking into account how empiricism has functioned in the past, and how it is evolving in branches of the discipline, shows the possibility of more positive, reflexive approaches to scepticism and to the role of interpretation in the making of historical knowledge.