Ecofundamentalists and postmodernists on the left, conservative nationalists and nativists on the right.

Both are symptoms of a splintering polity and among the causes of disenchantment with Australian democracy, according to a discussion paper published by parliament’s nationhood inquiry.

The Labor leftwinger Kim Carr and conservative Liberal Amanda Stoker raised eyebrows in July when they set up the legal and constitutional affairs inquiry into “nationhood, national identity and democracy”, with the Greens warning it could be hijacked by those with extremist views.

A discussion paper, published on Monday by the Labor-majority committee chaired by Carr, lists ecofundamentalism and identity politics alongside rightwing ideologies as a source of “intolerance”, although Carr told Guardian Australia he believed rightwing nationalism was the bigger threat.

The paper noted that ideas “once considered fringe now command substantial support”, such as populist, conservative nationalist and nativist ideologies.

“They tend to emphasise sovereignty and preservation of national identity.

“Their supporters appear to seek political outsiders who represent ‘the people’, as distinct from ‘the establishment’ and ‘elites’.”

The paper argued populist parties had peeled working-class voters from centre-left parties while also undermining “mainstream parties on the centre-right”.

“Many observers are concerned that these ideologies do not respect democratic norms and conventions. Some suggest that they reflect a ‘post-truth’ politics that draws on emotion instead of expertise and evidence.”

The paper also blamed “more extreme movements of the eco-fundamentalist and postmodernist variety” on the left of politics.

“These movements are often adherents of notions of identity politics and hold perspectives that would inhibit free speech in a way that has the potential to contribute to the division outlined above, fostering an intolerance of differing perspectives in a way that may well alienate other segments of the community from democracy, as they come to believe that their perspectives and contributions are unwelcome in the public space.”

The paper noted declining levels of public trust in Australia and other democracies including the UK and US, arguing that “political divisions appear to be increasing in the face of rapid economic, social and cultural change”.

These changes were a particular threat to “social-democratic parties or other movements that work through these institutions to implement a reformist agenda”, it said.

“Ultimately, these changes have the potential to weaken liberal democracy itself.”

Carr said the greatest threats to democracy were coming “predominantly from the right, not left, in this environment”, citing “radical nationalism” in Europe and the Americas.

“There is a fundamental problem with the political system’s ability to communicate effectively with the electorate,” he said.

“People will hopefully take the opportunity to say not just their perceptions of the problems with Australia’s democracy but also to propose solutions.”

The Greens senator Nick McKim, the only minor-party member on the committee, said he had “never seen anything like” the inquiry, confessing he didn’t “really understand what it’s about” and describing its terms of reference as “a bizarre grab-bag of issues”.

“If the [discussion paper] is suggesting the ecological movement is a threat to democracy then I couldn’t disagree more,” he told Guardian Australia.

“The biggest threats are corporations buying political outcomes with their donations and foreign governments’ interference.

“Environmental campaigning in a peaceful, non-violent manner to protect nature and advocate for strong climate action is just the opposite – it’s an attempt to save democracy.”

At the 2019 election the vote of minor parties and independents reached a new record, with almost a quarter (24.7%) of first-preference lower house votes going against the major parties and 11% of voters deciding their vote on the day of the election.

According to a Guardian Australia analysis, electorates that swung harder to the Liberal and National parties were more likely to have higher unemployment, lower income, lower levels of education and fewer migrants.