When the Green Party, by way of its London Assembly member Jenny Jones, appeared to endorse the recent anti-GM protests at Rothamsted Research in Hertfordshire, which involved a plan to “decontaminate” (read “vandalise”) a wheat trial, its commitment to science was loudly called into question. Writer Nick Cohen branded the protest organisers a “quasi-religious movement”, adherents of the “green faith” who harboured “an almost pagan delusion that nature is pure and must be saved”.

Mark Lynas, author of The God Species and a longstanding critic of environmentalist orthodoxy, is similarly scathing. “There’s a sense that a substantial proportion of conventional eco-philosophy is not based on rational empirical evidence,” he says. “They claim to be comfortable with science on climate change, but show the reverse inclination when it comes to issues like GM and nuclear power.”

The modern Green Party owes its origins to A Blueprint for Survival, an environmentalist manifesto that occupied an entire issue of The Ecologist magazine in 1972. Its call for a return to small-scale, self-sufficient communities was couched in distinctly mystical language. “[T]here is no valid distinction between the laws of God and Nature,” it said, “and Man must live by them no less than any other creature.” The punishment for disobedience would be “famines, epidemics, social crises and wars”.

Small is Beautiful, a 1973 collection of essays by the economist EF Schumacher, was equally influential. Schumacher called for a radical decentralisation of society, an “economics as if people mattered”. Although he coined the term “Buddhist economics”, Schumacher was actually a Catholic who described his project in theological terms. “If we can just regain the consciousness the West had before the Cartesian Revolution, which I call the Second Fall of Man, then we’ll be getting somewhere,” he said in 1977.

Schumacher’s ideas are kept alive by the Schumacher Circle, a network of organisations that includes the Soil Association, the organic lobby group co-founded in 1946 by Lady Eve Balfour and of which Schumacher was once president. Like Schumacher, Balfour was deeply concerned about human hubris, the deadliest of all sins (“Close contact with nature effectively counteracts any tendency to overrate the achievements of man.”). She was also a proponent of biodynamics – an agricultural system devised by the Austrian occultist Rudolf Steiner, described by sceptic Brian Dunning as “a magic spell cast over an entire farm” – which the Soil Association promotes to this day.

But while the movement’s anti-modern and pseudoscientific heritage is clearly still present, it is being challenged by a new generation of resolutely pro-science activists. “If you’ve not been trained to use an evidence-based approach to form your opinions then you will be likely swayed by emotive campaigns,” says environmental scientist Bex Holmes, who stood for the Scottish Green Party (distinct from Jones’s Green Party of England and Wales) in May’s local elections. Her advice for rationalists is to get actively involved and push for evidence-based policies: “Don’t moan, take action.”

Lynas is not so sanguine. “The Greens haven’t trademarked environmental concern and they don’t own it,” he says. “We’ve got to think for ourselves, that’s what the tradition of the Enlightenment is all about.”