Even by the shaky standards it has set during its first year in office, the Abbott government gave a singularly unimpressive account of itself last week. While there was no shortage of blame to go around — Treasurer Joe Hockey for his tone-deaf self-pity, Attorney-General George Brandis for dropping the ball on metadata, and Prime Minister Tony Abbott because that’s where the buck stops — my own nomination for worst-on-ground performance goes to Senator Eric Abetz.

Where other ministers at least blundered while pursuing strategically comprehensible objectives, Abetz’s wander through the minefield of abortion was essentially an unforced error and would have counted as such even if he’d had his facts in order.

Abortion forms part of a uniquely vexing category of issues that exercise the most deeply held moral convictions, with the potential to alienate vast numbers of voters and place enormous strains on the delicately constructed coalitions that characterise two-party politics. This, rather than concern for parliamentarians’ freedom of expression, is the reason parties have been uniquely willing to relax the usual death-grip of party discipline by allowing conscience votes on same-sex marriage, euthanasia, stem cell research and abortion pill RU486.

While individual MPs might use such issues to court favour with particular constituencies, they rarely grant their party any favours by doing so. Cory Bernardi is the outstanding example in the current Parliament of a politician who has built his brand on unorthodox positions on social issues, but his efforts have earned him what must surely now be a permanent place on the backbench.

By contrast, Abetz spoke with all the authority of one of the government’s parliamentary leaders when he voiced support for a link between abortion and breast cancer that has eluded mainstream medical research. Furthermore, he chose as his platform a television program expressly marketed by the Ten Network as its young and funky take on current affairs (the bewildering involvement of Steve Price notwithstanding).

The latter aspect of Abetz’s folly underlines a deeper cause of concern for conservative politics, namely an ongoing liberalisation of attitudes across a range of social issues. This can be illustrated with reference to the Australian Election Study series, which consists of comprehensive surveys of voting behaviour and political attitudes conducted by Australian National University after each federal election. The series has run without interruption since 1987 — a time when conservatives emboldened by the ascendancy of Ronald Reagan and Margaret Thatcher perceived a counter-offensive under way against the permissiveness unleashed by the 1960s, which was held responsible for crime, drug addiction, the AIDS pandemic and the decay of the family unit.

“The traditional conservative positions are losing the battle of public opinion and appear sure to continue doing so.”

The chart below shows the progress of “liberal” responses in the surveys to three key social issues: abortion, the death penalty and homosexuality. In the first example, support for abortion on demand is shown to have grown steadily to reach a new peak of 61% in the 2013 survey. Most of the remainder favoured an option allowing for abortion under special circumstances, with support for a complete ban starting at only 6.4% in 1987 and further declining to 3.7% in 2013. The slow and steady nature of the change reflects a generational effect, with the 2013 survey finding 64% of respondents aged 35 or under supporting abortion on demand compared with 55% among those 55 or over.

However, the most remarkable transformation in attitudes over the past three decades has involved homosexuality, a fact the chart fails to properly illustrate owing to the lack of a consistently worded question. This is telling in and of itself, as the 1987 survey question related to the legalisation of acts between consenting adults — then opposed by 46.4% and supported by 29.5%, but now obsolete as a matter of serious controversy. The battle front has since moved on to same-sex marriage, for which an even balance of opinion in 2007 had transformed to a clear plurality in favour (48.6% to 30.3% in the 2013 survey) just six years later. Reflecting this distinction, the chart shows the 1987 finding linked to the later same-sex marriage results by a dotted line.

Even support for the death penalty, while still favoured by 48.5% of respondents in 2013, has been on an unmistakable downward slide, with opposition mounting from 23.5% in 1987 to 35.3% in 2013. The one curious exception to the broader trend relates to marijuana decriminalisation, for which support has remained stuck in the low-30s even while a dramatic shift in favour has occurred in the United States (where the rate of unqualified opposition to abortion remains at least three times higher than Australia’s).

So far as issues touching on sexual morality are concerned, the message from survey research is clear — the traditional conservative positions are losing the battle of public opinion and appear sure to continue doing so. That being so, the first order of business for the likes of Eric Abetz should be to keep the issue agenda focused firmly on their party’s real strengths: economic management and national security.

As for Cory Bernardi, there’s a theory abroad that his close relationship with Senator Bob Day portends a future defection to Family First. For all concerned, that might not be a bad idea.