We always lament politicians’ lack of candour and preference for staying on-message, rather than treating us like intelligent people. And the problem is undoubtedly getting worse with Kevin Rudd, a thoughtful and engaging interlocutor off-the-record, who has taken rigid public messaging to heights hitherto never seen.

So spare a thought for Joe Hockey, who on Tuesday spoke intelligently and candidly and has copped a bagging for his troubles.

I’ve regularly been calling Hockey a lightweight but his performance at the CEDA lunch earlier this week showed substance and maturity.

Hockey got considerable attention with his suggestion that the Government should try supporting residential and commercial property borrowing through extending the government guarantee to mortgage-backed securities, rather than directly pumping liquidity into the relevant markets through its $8b funding for residential mortgage-backed securities or the Ruddbank proposal. This is a shift for the Coalition, which has been sniping away at the bank guarantee virtually since the Government announced it in the middle of the financial crisis last year, but welcome nonetheless (see Christopher Joye’s excellent discussion at his Business Spectator blog).

So far, so good.

When it came to the Q&A session, though, Hockey went for candour rather than the usual platitudes, admitting that the criticism that the Howard Government had spent too much on middle class welfare was “reasonable”. I put a similar question to him after his Budget Reply speech a couple of weeks ago and his response was to note that there weren’t too many people at the time urging bigger surpluses. He was still referring to “hindsight heroes” on Tuesday but it marked the first time someone from the Howard era other than the possibly slightly biased Peter Costello was prepared to acknowledge some fiscal indiscipline.

In doing so, Hockey promptly earned the front-pager “Hockey creates more turmoil for Turnbull” at The Oz, although his admission that there might have been an arguable case for ditching the tax cuts that kicked in from yesterday also caused angst. Hockey is still entangled in that issue in the Fin Review today, after trying to clarify himself.

Just to rub it in, Wayne Swan materialised from the Utegate-induced exile to call Hockey “sloppy” — his favourite and now rather well-worn joke about his opposite number — and describe his remarks as “extraordinary”.

In fact his remarks were anything but sloppy. Hockey won’t get too much argument from any economists about the level of middle class welfare during the Howard era, and he probably won’t get too much on the tax cuts either, which a lot of economists regard as misdirected and the last thing we need given the long haul it will take to return us to surplus (some of us think they were needed to maintain political credibility, but that’s another matter).

Hockey did do something extraordinary, though. In preparing his speech, his staff misread a graph on the size of automatic stabilisers in the Bank of International Settlements’s Annual Report — it’s on page 112 if anyone cares to look – to make a point about how the Government didn’t need such a big stimulus package. When the error was pointed out, he copped to it.

Can you imagine Wayne Swan or Kevin Rudd readily owning up to a simple error like that? It took the Prime Minister several thousand words to eventually own up that he’d got an unemployment number wrong in Parliament last year.

What Hockey did was to break the supposedly golden rule that the Liberals must not under any circumstances allow the record of the Howard Government for competent economic management to be besmirched, lest they go the way of Kim Beazley’s Labor, which lost ownership of the economic reform mantle of the Hawke-Keating years.

The problem with this rule – important as it is to any party aspiring to lead the country during a prolonged economic downturn – is that it makes it hard for Hockey to look sensible or participate effectively in economic debates. The Howard Government started off very well as economic managers and, like the Labor Government before it, went downhill. There are creditable aspects of its record that should be defended — the early fiscal discipline, the introduction of a mostly-intact GST, the first wave of IR changes, the Future Fund – just as there are other, disastrous aspects of its record that cannot be defended.

By acknowledging that more complex reality rather than engaging in reflexive lauding of everything that occurred until November 2007, Hockey looks far more credible as a shadow Treasurer. He won’t get any credit from the mainstream media or his political foes if he does, but he should stick with it.