As I watched Coles cower to complaints and decide first to provide free plastic bags indefinitely and then announce a deadline of 29 August, I was struck by how climate change has utterly destroyed the minds of conservatives.

Here was a pretty straightforward proposition to get behind – not least for those who believe in small government. In New South Wales and Victoria, unlike in other states where a legal ban on plastic bags has been in place for some time, Coles and Woolworths instituted a ban of their own volition.

The plastic bag ban is not really about climate change, it’s about conservation – the tool conservatives such as Tony Abbott used to counter criticism they did not care about the environment.

It was the thinking behind Abbott’s Green Army, with that old-fashioned personal-responsibility aspect about it. Get out and plant some trees, pick up some rubbish and huzzah, look at me, I care about the environment, and unlike those greenies who just want to destroy jobs, I’m doing something that matters.

But sigh, no. Conservatives have been rendered so bereft by climate change that anything carrying even the slightest taint of an environmental impact is viewed with distrust. And so the plastic bag ban quickly became a new focus of the culture wars.

It’s all rather odd, but fits perfectly within a strain of thought that has decided the way forward is to ignore evidence and instead pursue an ideology of wilful ignorance.

It has led to the point where there are barely any conservative commentators worth reading or listening to. It’s not that there are no intelligent conservative thinkers, but the lunacy of climate change denial and distrust of expertise has so infected the conservative media that prominence is now almost exclusively given to those for whom a worldwide conspiracy is more believable than reports by multiple universities and public agencies.

What’s more, their realisation that they can spout their views free of supportable evidence on this issue has also led to an unlocking of all manner of views they once kept hidden, but which now come forth with great delight.

It’s a small jump from viewing climate change as a global conspiracy to decrying the conspiracy of “cultural Marxism” in either ignorance or lack of care about its antisemitic roots.

Add together the Australian conservative cultural cringe that always sees them flock to embrace the most D-grade right-wingers from North America – such as Lauren Southern – and you get a rather pathetic mix of dull thinkers shifting ever more towards promulgation of hatred in an effort to imitate those so lacking in insight that their arguments get defeated even as they espouse them.

No longer do such voices feel even a need to pre-empt criticism as they did in the old days by saying “some of my best friends are...” Now the full ugliness is put on display – such as this week when Andrew Bolt was given free rein in his syndicated News Corp column to criticise, in his view, the clusters of Chinese, Vietnamese, Indians, Jews, and Muslims in parts of Sydney and Melbourne, as well as Italian migrants who still speak Italian at home and a quick drive-by at Indigenous people just to ensure he completed his full racial bingo card.

The other problem is this virus of odious ignorance has also infected the conservative parties.

We see this most visibly in talk of migration and climate change, and so virulent is this strain of ignorance and hatred that the remaining members in the Liberal party who might have kept some slight connection with rational thought now self-censor both their politics and their policy.

The national energy guarantee being pushed by Malcolm Turnbull and Josh Frydenberg is a prime example. It is at best a policy that does little harm but virtually no good, but which is miles removed from the sentiments on climate change policy Turnbull espoused nearly 10 years ago.

The best you could argue is that instead of raising the share of renewables in the energy sector to 34% by 2030 as would occur should no new policy come into effect, it will raise it to 36%.

Of course, all this needs to be taken on faith, given the government is not releasing the full modelling of the scheme. But really, why would you want people to see evidence? That would be like believing granting $444m of public funds to a charity should require some sort of tender process, and that is just not the way things are done by this government.

But even this is too much. Abbott remains opposed to the Neg because he claims the policy is about lowering emissions rather than power prices. It appears the fact that emissions will actually increase under the Neg is not enough to satisfy him.

What’s worse is that while Abbott and Co are already against the emissions reduction target of between 26% and 28% by 2030, they are even more opposed to the possibility floated by Frydenberg of allowing the target to be reviewed in five years’ time. This opposition could see the target set in legislation, meaning the ability to change this miserable policy would be beholden to future Senates should a political party not divorced from reality gain power in the years ahead.

And you would think reality would be hitting the conservative side of politics pretty hard right now, given the drought affecting vast parts of NSW and South Australia. Yet even here we have Barnaby Joyce threatening to pull his support (such as it is) for the Neg should it mean the agricultural sector is required to reduce its emissions.

Thus we remain stuck in a situation where the bar seems set at hoping to achieve a third or fourth-best policy, all because one side of politics has become so bereft of thought that not only is it unable to admit that climate change exists, it cannot even cope with the thought of people having to reuse shopping bags.

It would be funny were it not so pathetic.