The current expectation that politics should be an ideology-free zone seems to stem from the early days of New Labour, who believed that in order to win power it was necessary to convince the electorate that its policy-making process would be free from (left-wing) ideology. In the 1997 manifesto, Tony Blair proudly claimed that New Labour would not be driven by 'outdated ideology': what will count is what works.
'What counts is what works' subsequently became the leading mantra for New Labour as it drove forward a purported model of 'evidence-based policy'. However, there are two obvious problems with the idea of evidence-based policy. The first is that it believes that science can provide an objective answer of what policies to choose ('what works'); the second is that politics can be removed from the policy-making process in favour of objectivity and pragmatism ('what counts'). As New Labour and the electorate found out, scientific evidence cannot provide answers to difficult moral, political questions. Further, when we mistakenly claim that it can, we project an image of politics as a scientized, mechanistic and deeply unpolitical process.
Hence now, the Coalition's more overtly political reforms are attacked as being inspired by ideals, not evidence. Not only is conservative ideology attacked, but the whole idea of ideology itself - of principle and purpose - is mocked and discarded by critics. However, when we attack and dismiss ideology, we attack almost the central point of politics itself: that politicians and political parties should actually believe in something.
Yet the evidence-based view marches on. In a new book, the economist Tim Harford advocates an even more pragmatic approach to politics based upon trying new policy approaches irrespective of political principle. However, I think it is time to stand up for principle and values; when our politicians cease to believe in things, it is highly likely that we will too.