Remember three weeks ago when the secretary of the Immigration Department, Andrew Metcalfe, quietly advocated a bit of a sensible look at a whole bunch of areas in Australian immigration policy?

Like whether detention was a deterrent, and how best to balance our humanitarian obligations with our border protection interests, and so on?

Mr Metcalfe was stamped out like a small grass fire in about five minutes; Scott Morrison issued a press release demanding that the Government clarify this dangerous new note of ambivalence in the operators of Fortress Australia, and Chris Bowen's office briefed that Mr Metcalfe was definitely not questioning mandatory detention in an actual questiony way. He was just restating the questions facing the parliamentary inquiry he was addressing at the time. Not seriously suggesting they should be answered, or anything.

Mr Metcalfe is looking a tiny bit prescient now, after Hurricane High Court's brisk rearrangement of the policy furniture.

But what are the odds we'll get a reasoned examination of this policy area? What's happening at the moment, on asylum seeker policy, is not actually a political debate. Both major parties want to take a "tough" line on border protection; they're just trying to trip each other up on detail. (What is truly impressive is that they can actually hold a simultaneous, equally aggressive argument on fiscal prudence without anyone questioning whether $1 billion a year isn't rather a lot to be spending on shunting a few thousand people round the region in one way or another.)

The Government's response to the High Court's decision – a declaration that all offshore processing is now buggered – has a touch of the bat/ball/going home about it, and it is difficult to escape the suspicion that Mr Bowen and colleagues are happy to squish Nauru on political, rather than policy grounds.

And Mr Abbott's generous offer of assistance is about as benign as a squirty lapel flower. "I'm trying to help the Government," he maintained this morning. Which is quite sincere, so long as you interpret "help" as "help the Government into a position in which I can better administer this atomic wedgie".

Mr Abbott argues that his preferred methods are what stopped the boats dead in 2001. Chris Bowen argues that his Malaysia Solution was already working, though concedes that it would have worked even better if it had actually happened.

Later today, the Cabinet will go back to the drawing board. Or maybe, seeing as the High Court has reduced it to pre-drawing board technology, it will start by building a drawing board. Do not expect a fast decision here.

In the meantime, perhaps we can bring some independent perspective to the debate. As so often is the case, it's available in spades from the Parliamentary Library, which has just updated its analysis of boat arrivals in Australia over the last 30 years or so.

I have borrowed a chart from the paper, which shows the peaks of boat arrivals since 1976.

Australia has always taken large numbers of immigrants, but boat arrivals only started in April 1976, when one boat carrying five Vietnamese men arrived in Darwin. The subsequent "first wave" of boatpeople lasted about five years and its members were resettled, though not without trouble - the 1977 election campaign featured a protest by the Darwin branch of the Waterside Workers Federation, demanding an end to "special treatment" of refugees. A total of 2,059 people arrived in this period.

The next "wave" of boatpeople (from Vietnam, Cambodia and China) started in November 1989, and the Labor government introduced the policy of mandatory detention in 1992. There was a dip in arrivals the following year, as you can see, but the second "wave" still peaked at 953 in 1994.

And the third, this time mainly of Middle Eastern asylum seekers, really started to surge in 1999. The Howard government introduced Temporary Protection Visas in October 1999. As you can see from the graph, the TPV arrangement did not reduce boat arrivals on its own – they still grew fairly steeply for the next two years to a peak of 5,516 in 2001, then dropped away to just one boat, bearing one person, in 2002.

What happened in 2001?

Lots of things. The Tampa crisis, then the September 11 terrorist attacks in the US, and then the Australian federal election, in quick succession. But on September 26, 2001, the parliament passed a package of six bills, which excised chunks of Australia and external territories from our migration zone, removed asylum seekers' access to the Australian legal system, and legalised the removal and detention of asylum seekers to a third country for processing.

The common assumption is that these measures were forced through by the Howard government, but the truth is that they were done with the support of the Beazley Labor opposition.

One other thing that happened in 2001 - in October, just weeks after all these laws were passed - was that 353 people drowned when their boat, now known as SIEV-X, sank on its way from Indonesia to Australia. Of the dead, 146 were children.

As you can see from the chart, boat arrivals were low until the election of the Rudd government, which abolished TPVs straight away and then closed Nauru in 2008. The Rudd government maintained the migration zone excisions, and kept Christmas Island as an offshore processing centre.

Instead, it beefed up spending on border protection and anti-people-smuggling exercises, announcing a $654 million package in the 2009 budget.

The Malaysia Solution was announced in May this year.

So have a look at the chart - draw your own conclusions about what worked and what didn't. If this is to be an argument about whose methods best reduce boat arrivals, then it might help to look at the policy chronology.

If Mr Metcalfe had his way and we asked all the difficult questions involved in this area, we'd need a lot more charts.

Annabel Crabb is the ABC's chief online political writer.