The science of Costellogy, which is defined in the Crikey Dictionary of Terms We Just Made Up as “the study of the actions and statements of Peter Costello in order to determine his political future”, has been with us for over a decade. But you’d have the thought the last section had been written on 25 November, when he declared he was bailing out.

Not a bit of it. As The Age demonstrated on Saturday, it doesn’t require the slightest action on the part of the subject to keep this pseudo-science going strong. Indeed, given the denials of Tony Abbott, it apparently doesn’t require much from anyone to keep it going.

Costello has barely said a word in public since the election. He’s had a crack at his successor, but otherwise said even less than his former Prime Minister. And he has said nothing about his future plans beyond what he said in November.

And that’s not just to the press. It’s clear that no one – at least no one who is willing to speak – in either the parliamentary party or the Liberal Party organisation has any idea what he’ll do. One of the small gratifications for Costello in all the mess the Liberal Party finds itself in is the extent to which his silence has made him fascinating to both the press and his colleagues.

So let’s go back to first principles – the very basics of Costellogy. What do we know for certain?

1. He has committed to leave Parliament this term for a business career.

2. He has a school-age daughter.

3. His wife has had a job with ANZ Trustees in Melbourne since August 2006.

4. He spent much of his period as Treasurer criticising corporate remuneration and attacking the banking sector.

5. He has never fought for the leadership of his party.

What can we reasonably infer from that? Firstly, that any business opportunity – which would have to be something appropriate for an ex-Treasurer – would likely have to be Melbourne-based until his children have finished school and his wife has fully explored opportunities in her current job. That narrows his possibilities significantly, especially international ones.

Secondly, he is unlikely to be hugely popular with the business community. You can add to that the unfortunate history of most Liberal party figures in the corporate world, which suggests they strongly support capitalism but don’t know a lot about it.

And, more problematically, Costello’s CV basically consists of busting unions and running an economy during an extended, low-inflation boom. Hmmm. Not much call for that sort of thing at the moment, alas.

Accordingly, the stories from the business community that Costello has not been overwhelmed with commercial offers make sense.

The leadership scenario being offered by Liberal Party sources – and which found its way into Michael Gordon’s Age piece – is that when – as everyone assumes – Brendan Nelson falls over, Malcolm Turnbull will step in, but may prove too inexperienced and incapable of bringing party conservatives on board. If there’s a merger with the Nationals anytime soon, that will be doubly likely, as a lot of Nats can’t abide Turnbull. At that point, a desperate party will turn to Costello.

Some of us peddled this fantasy the day after the election, noting how immensely satisfying it would be for Costello to have the party that refused to cop him while Howard was around come to him and beg for him to take charge. It also fits what we know about Costello’s aversion to fighting for the leadership.

The flaw in this plan is that, even if the economy deteriorates, voters have consistently demonstrated a dislike of the man. And with Kevin Rudd and Julia Gillard attacking him as the bloke behind all those interest rate rises, the Treasurer too weak to contain a spendthrift Prime Minister, that’s unlikely to get any better. Then again, by that time, the only alternatives would Smokin’ Joe Hockey, Tony “People Skills” Abbott and the Dr Frankenstein of Workchoices, Julie Bishop.

Either way, it’s enough to keep the Costellogists happily occupied for months to come.