While Penny Wong was yesterday lamenting how irresponsible the opposition is in not detailing its fiscal policy nine months out from an election, the government was demonstrating exactly why any sensible opposition declines to do so. This morning, via Peter Martin in Fairfax papers, we got a partial analysis of the costs of three opposition policies, which would cost business $4.6 billion immediately.

The three policies are the levy for Tony Abbott’s paid parental leave scheme, the removal of small business tax breaks as part of the carbon pricing package and the removal of loss carry-back provisions.

The analysis was prepared by Treasury. It is standard for government departments to prepare analysis and briefing on opposition policies at the request of ministers’ offices. I recall discovering, as a young Department of Transport graduate in 1994, an entire drawer full of “confidential” files devoted to assessing the impact on transport of the Fightback! package and briefing ministers on it. It’s one of the privileges of incumbency that not merely can you get an army of public servants to dissect your opponents’ policies, you can then pick and choose what part of that dissection you release to the media, with public servants prevented from ever pointing out that you have cherry-picked or willfully misinterpreted their analysis.

Today’s analysis, for example, didn’t include anything on the impact on business of removing the carbon price. Bear in mind, also, these are policies that actually increase government revenue, although in the case of paid maternity leave it’s to fund middle class welfare by transferring money to middle and higher-income working mothers.

The message from the government is thus: the opposition is irresponsible in not giving us fiscal policy detail, but it reserves the right to misrepresent what little detail the opposition does release. In which case, Joe Hockey is being eminently sensible in refusing to release any detail until the election campaign.

While Fightback! was at the extreme end of political suicide notes, we’ve now gone to the other extreme. There is no benefit for oppositions to release policy detail outside the hurly-burly of an election campaign, when analysis gets lost in the flood of policy detail.

And this is a broader, cross-partisan version of the problem that first plagued the Labor Party and now looks set to trouble the Liberal Party.

As Labor has found to its immense cost, if you elect to abandon public discussion of policy your capacity to effectively prosecute policy when in government atrophies. For 20 years, Labor preferred to keep policy debate to a minimum, especially at national conferences, for fear of being portrayed as divided. In opposition, it adopted a small-target strategy to prevent the Howard government using incumbency to attack it. The result was that its capacity to sell its policies, to debate and explain them, withered through non-use. The party of Hawke and Keating, of Button and Walsh, “good policy can be good politics”, became the party of Kevin Rudd and Julia Gillard, too scared to take on Abbott at an election over an emissions trading scheme.

The same thing is now occurring to the Liberals. An extraordinarily effective negative politician, Abbott is, on the few occasions he has tried to be one, a dud positive politician. Sometimes this is because his policies themselves are rubbish. His speech about deregulation last week, for example, was a juvenile collection of right-wing nostrums that betrayed a complete absence of awareness of how government operates.

But Abbott struggles to explain the most basic policies. Amazingly, voters male and female actually prefer Labor’s paid parental leave scheme over his despite it being vastly more generous. His approach to media management makes things worse. Shadow ministers are discouraged from giving long-form interviews in which they can be grilled at length. And there are rarely detailed policies to discuss if they do them. The emphasis is on the day’s talking points.

Skills unused atrophy. It’s what happened to Labor, right across the party, after 1996. It’s what’s happening to the Liberals under Abbott. And the real consequences won’t be felt until they’re back in government, where being negative won’t help and you actually have to explain policy to voters.

What to do? They’d be mugs to subject themselves to more headlines like today’s. And yet the longer they go avoiding putting policies out, the worse they’ll be when they return to power.