Scepticism represents a permanently dissenting voice within philosophical history, casting doubt on the subject's founding principles and thus its ability to construct logical arguments. It can be considered a particularly pure form of dissent, therefore, taking issue with the whole of the philosophical enterprise, or at the very least suggesting that it can never really live up to its claims, which is why it is playing such a central role in this study. One of the main reasons that such a voice is necessary is that Western philosophy has had a distinct tendency towards system-building over the years, as in the work of such figures as Hegel and Marx, the latter having a hugely significant impact on the development of twentieth-century politics in the form of the communist movement. Earlier examples of this approach can be found in the work of religious philosophers in the Christian tradition, whose goal had been to reinforce their theological belief system rather than point out its shortcomings and contradictions, which to a non-believer are all too obvious (the need for divine intervention and miracles to make the system hang together, for example). Gaps were to be glossed over, not emphasised, and the sanctity of the system was to be preserved at all costs. No-one wanted to make the existence of God seem in any way doubtful, or to raise unanswerable objections to any core Christian doctrine. Faith had to win out, and that meant it was the role of philosophy to provide arguments proving the truth of Christian belief. Equally, no communist philosopher would set out to undermine the Marxist worldview or the canon of works lying behind it. The system dictated what could and could not be said and policed all of that very closely indeed, determined to present an image of being in complete control of its area of discourse. From such a perspective dissent of any kind whatsoever could only be viewed as malicious in intent.

Scepticism is critical of all such schemes, arguing that their foundations are unreliable since they depend on unsubstantiated assumptions, and that truth is a relative concept instead of an absolute: certainty, for the sceptic, always remains out of reach –a message that few politicians heed.