For tergiversation, the word lying will more or less substitute. Or not exactly straight lying so much as evasion of the truth, a conscious effort, sometimes by omission as much as commission, to mislead, and a going back on things that one has said before.

I do not use the word often, and, mostly when I do, it's to be deliberately a little bit circumlocutious myself. I am a polite fellow who does not want to cause offence by directly calling another a liar.

In the same context, I often use the words dissembling and prevarication when people are being ''economical with the truth''. Dissembling, strictly, means concealing or disguising. In practice it means surrounding the facts with so many distractions, additions, misleading remarks and plain gabble that it is impossible to discern where the truth lies. Joh Bjelke-Petersen, and one of his early press secretaries, Clive Palmer, were natural dissemblers, if only because one hardly knew one's own name, let alone theirs, after even a question about the weather.

Prevarication does not usually mean outright lying, so much as a conscious effort to tell anything but the truth. It can involve answering questions one was not asked. It can involve allowing oneself to be distracted, during the answer, and going off in some other direction so that one never does address the question asked.

Dissembling and prevarication, and even tergiversation, come very commonly from politicians, not least at question time in Parliament. Tony Abbott is an absolute champion at it; so were any number of Labor prime ministers, including Julia Gillard and Kevin Rudd. The techniques may be ingrained in the political personality - and not necessarily because politicians are natural or instinctive liars, so much as because no politician ever likes to admit being wrong, or foolish, or human, or to admit that something might have been misjudged.

Sometimes, alas, whatever it was is so obvious that it cannot be directly and bluntly denied with any credibility. Then, it is thought, the obvious truth is best avoided by bluster, misleading, by drawing attention to the supposed deficiencies of the questioner, or the alternate proposition, or by the invocation of facts and circumstances which are said to place the ''facts'' in a different light.

One of the arts of tergiversation, dissembling and prevarication involves the use of escape clauses, slight reservations or (literal or metaphorical) crossed fingers so as to be able to deny even plain facts. Thus some politicians habitually use conditional phrases alongside even dogmatic statements, initially placing all of the emphasis on the absolute assertion, but later taking refuge behind the unemphasised condition. (''Yes, I said 'dead, buried and cremated', but I made no mention of exposing the body to vultures, and so, obviously, my statement cannot stand.'').

Malcolm Fraser did this habitually. He would say he would not do something, and be reported as such. Later, when he did the opposite, he would insist that his statement be read in context, and helpfully supply a transcript which would make clear some tiny reservation or condition - not emphasised at the time - which he would claim to be the let-out. This can be a ''clever'' trick, but does not much impress, and many journalists, and not a few members of the public, learnt that one should never trust anything he said, particularly any statement of future intention. Yet he was not usually, strictly ''lying'' - unless one considered lying to include conscious misleading as much as the telling of a deliberate untruth. After all, no statement of future intention can be a lie, can it?

Well, Tony Abbott said it could be, when he accused Julia Gillard of lying when she said there would be no carbon tax under a government she led. Gillard could have used any number of weasel words to justify her subsequent decision to introduce a carbon tax, but decided, apparently, to ''wear'' criticism of her change of mind, induced by agreement with the Greens in composing a minority government. Presumably she thought that criticism of her breach of faith would ultimately subside as it did about a breach of faith by then health minister Tony Abbott about Medibank promises at the 2004 election. Abbott, when making his promise, had no doubt intended to keep it. So, no doubt, did Gillard. But circumstances changed, just as did his own attitude to such matters.

A correspondent this week suggested that Tony Abbott, as a student of the Jesuit secondary school, St Ignatius, Riverview, had no doubt learnt a practice, often attributed to Jesuits, of equivocation or ''mental reservation'' said or supposed to excuse lying in extremis. The practice has been described by bigoted anti-papists of being ''Jesuitical'', defined in my Shorter Oxford as ''having the character once ascribed to the Jesuits; deceitful or dissembling''.

This meaning entered the English language during the time of Queen Elizabeth I, when England was under Papal Interdict due to the advent of Protestantism, persecution of Catholics and bans of Catholic clergy. The Pope was said to have authorised - perhaps commanded - rebellion against Elizabeth, and, on this account, Catholic priests were seen not only as agents of a foreign state but as spies, insurrectionists, terrorists and saboteurs. Nevertheless priests were smuggled in, and occasionally caught, cross-examined, tried and executed.

It was alleged of many of these priests that they had been instructed in ways of misleading the authorities without actually lying - which would be a sin. One might read a sentence very literally, and deny it, because some tiny fact implied or explicit, was not true. One might answer a proposition as a general statement rather than as an assertion of facts at a particular moment, and (in what one said) deny the general proposition because it was not always true, or demonstrated to be true. One might, as it were, cross one's fingers as one spoke. One might, indeed, do almost anything done at question time.

Elizabeth's inquisitors thought all of these techniques involved lying, and whenever answers did not suit, they were taken to be lies, and corroboration of the supposed technique.

The techniques were described as Jesuitical because so many of the Catholic martyrs, such as Edmund Campion, were Jesuits. Even poor old Guido, or Guy, Fawkes, was accused of being Jesuitical under interrogation.

The interesting thing about this canard against the Jesuits, and their schools, is that it has come to be believed by many Catholics as well as those who hated Catholics. The Jesuits were a highly intellectual order, and, over many centuries, the church, and many of its teachers, were deeply anti-intellectual.

The idea that Jesuits were ''clever'', that they were, in some manner, like lawyers able to twist the truth and prove that black was white, was widespread, even in the Catholic establishment. Indeed, the correspondent who accused Abbott of being Jesuitical was once, I am sure he would not mind my saying, a Catholic priest.