In the long ago days of being an undergraduate, in the months following Mrs Thatcher’s first general election victory, there were friends who mocked the degree for which I was studying. “How can you have a bachelor of science degree in economics?” Those who studied mathematics or physics or chemistry or biology hadn’t much regard for the idea that economics might be scientific. The usual riposte was that without economics, there would be no resources for their sciences. It wasn’t as though economics hadn’t a basis in experimental methods: the monetarist policies of the new government, the attempts at controlling the economy through controlling the money supply, were a constant series of experiments. Policies were blunt, and often had little regard for those most affected, but the government attempted to learn what worked and what did not work and learned to adapt its thinking accordingly.

Economics had not the purity of some of the physical sciences, but it had the capacity for testing theories and discarding those that did not work. Being the subject that determined the allocation of resources in a society, it was hard to find a student whose approach was not shaped by their political stance, their beliefs about the ways in which a society should function. Most were pragmatists, accepting that sometimes the policies they might have opposed were those that delivered the social goods they desired, but there were also ideologues. In college days there were Marxist-Leninists and Trotskyites, and probably adherents of other shades of hard Left thinking, who rejected empirical evidence. If reality did not correspond to their theory, then rather than adapt the theory, it was the reality that was to be rejected. To try to point out that their ideology was leading them to make the wrong conclusions was to invite accusations of “false consciousness.”

As the referendum on marriage equality in Ireland draws close, the religious ideologues seem like the extreme Left of college days. The religious Right prefer to reject empirical evidence in favour of clinging on to their own definitions of reality; their assertions are matters of subjective theological opinion, yet they present them as if they are somehow comparable with scientific truth.

By 1979, the political Left had bought into many of the assumptions that undergirded liberal democracy, even the Trotskyites accepted there was a place for small private enterprises wanting to nationalize only the top “two hundred monopolies.” The religious Right have bought into much that is accepted as a norm in liberal democracy, watch the television evangelists and there will be women among them, something contrary to a strict interpretation of Scripture. It is odd that marriage equality should become the ground where the Right has decided to reject pragmatism, particularly as divorce does not seem a problem for many evangelicals.

The ideologues of the political Left became hardly more than a detail of history in the decades that followed, their rejection of reality leaving them marginalised. The ideologues of the religious Right are likely to share a similar fate.