“Do as I say, not as I do,” was the key message from last night’s speech by Treasurer Joe Hockey on his budget challenge.

The speech, given at an event hosted by a media outlet whose name I couldn’t quite see properly on the backdrop, laid out the basis for “hard savings”, “difficult decisions” in the “national priority” of “an ongoing and relentless focus on fiscal discipline and economic reform”. All fair enough.

But Hockey went beyond the usual cliches of the fiscal hair shirts and declared that fixing the budget had a “moral dimension” — indeed, it was a “moral imperative” because we don’t want to “squander our children’s future” like Spain and Greece did.

Implicit in such rhetoric, obviously, is that your opponents are immoral for their fiscal strategy in government. But the problem with a politician invoking morality is that it puts them on a playing field that is not, by and large, their natural turf.  That’s not meant in some populist, all-politicians-are-crooks way — in my view most people in federal politics, barring some exceptions, are there to serve what they believe is the national interest. Rather, invoking morality as a policy justification is problematic because so much of the political contest is fought with compromise, hypocrisy, inconsistency and deception. Politics, being about the pursuit of power, is amoral. Once you start throwing morality around, well, you can be terribly exposed.

For one thing, it’s hard to see the intergenerational morality in repealing a working, successful carbon pricing scheme and replacing it with a piece of climate change “policy” widely acknowledged as garbage designed to cover up the Coalition’s climate denialism. What will you tell your grandchildren when they ask you if you did anything to stop climate change, Joe? Will you tell them you actively worked to undermine genuine action to stop it? Because the longer you help delay action on climate change, the more future generations will have to pay, in higher prices, higher insurance premiums, higher taxes and lower economic growth in a world damaged by rising temperatures and more extreme weather.

And, one wonders, where was the “moral dimension” and “relentless focus on fiscal discipline” when Hockey was in opposition and Labor was trying to cut middle-class welfare spending? Hockey either opposed many of Labor’s savings measures outright or said nothing and let Labor cop the heat. The Coalition fought cutting back the private healthcare rebate to high-income earners tooth and nail and still vaguely “aspires” to restore the rebate to its former, exorbitantly expensive glory. Hockey was reported as calling Labor’s freezing of the indexation of family tax benefit thresholds “the politics of envy”, while Tony Abbott described it as “class warfare” — like many other things Labor did in government.

Still — “moral imperative”/”class warfare” — you say to-may-to, I see to-mah-to, yeah?

If Hockey had entered government and immediately begun acting according to his “moral imperative”, we could have put all that down to ordinary hypocrisy and the needs of opposition. But in November, Hockey abandoned Labor’s plan to reduce extravagant tax concessions enjoyed by superannuants earning over $100,000 a year, costing himself billions of dollars. He restored a fringe benefits tax rort — an actual tax rort — for novated leases, that Labor had moved to close, again costing the budget billions. He’s committed to dumping the mining tax as well as the carbon price. Hockey is talking to us about the “moral imperative” of fiscal discipline while handing billions to large companies, wealthy retirees and tax rorters.

Then there’s yesterday’s F-35 announcement — over $12 billion for planes that may or may not be delivered at some point, and may or may not have working software, assuming they’ve fixed the cracks in the turbine blades that grounded them all. At least the $5-odd billion Tony Abbott wants to spend on paid parental leave to show off his feminine side will stay here in Australia; the $12.4 billion that enabled him to play Tom Cruise with a fake jet yesterday will be dispatched to Fort Worth, Texas, although most of the other $12 billion that it will cost to run them will stay here.

But then the PPL scheme, and its quite remarkable generosity to women on high incomes, isn’t subject to the moral imperative either. Nor, apparently, is the $8.8 billion gifted to the Reserve Bank for no reason beyond faking up a budget black hole narrative.

The F-35 announcement was a little confusing. Now, try to follow me on this: Defence Minister David Johnston claimed that really the F-35s wouldn’t cost anything because the money was already “in the budget” in the years beyond forward estimates and been “building up”. Johnston appears to seriously think there’s a sort of “JSF account” somewhere in Defence with $12.4 billion in it that’s been earning interest. Instead, it’s a notional allocation in the government’s defence spending guidance over the next decade that doesn’t even have the status of forward estimates.

Except, anyone with a memory longer than five minutes should recall that just three weeks ago, Hockey was complaining there was a “massive increase” in defence spending beyond forward estimates and that it was a budget boobytrap, a fiscal “tsunami coming across the water” created by Labor.

Still, you say “tsunami”, your colleague says “it’s been building up and it’s in the budget.” To-may-to, to-mah-to.

Hockey says that everyone is going to have to share the burden repairing the budget. But the government’s decisions show how the burden will actually be distributed: big companies, the military-industrial complex, no matter how bad their products are, rich superannuants, high-income earners, tax rorters — they’re exempted from the whole “moral imperative” thing.

I still think Hockey genuinely wants to wind back unnecessary spending, which is laudable in a politician, and his long-term aim of budget sustainability is unarguable. You can forgive the rank hypocrisy of demanding now what he opposed in opposition, just as Labor has now reversed itself on some cuts it backed in government but now, from the convenience of opposition, doesn’t support. But you can’t forgive decisions that are dramatically cutting revenue, by up to $15 billion, while Hockey complains about the budget mess he has to fix. You can’t forgive claiming all will share the burden while the government’s favourites get a handout. And you can’t forgive a politician dressing all that up in morality.