Questions are fixed on a daily basis. Independent spirits are nobbled or bought off. We know about cash for questions - the subversion of representative democracy from outside. But what about its internal variants, such as knighthoods for silence? Committee places in return for dully loyal BBC radio interviews? Or Parliamentary Under-Secretaryships for helpful tip- offs? It goes on. It is rarely committed to paper (silly Willy) but accomplished through nods, hidden conversations and reassuring elbow-squeezes in the Members' Lobby. There is a case for saying that this staining of parliamentary purity has to happen.
These governmental baubles and cod-medieval vanities are the equivalent in the 1990s to the hollow but remunerative Crown offices given to "placemen" in the 1790s. A truly independent and unruled legislature would, so this argument goes, make it so difficult for the ruling party to be sure of getting its business done that the laws promised during elections would not be enacted.
Without sticks and carrots, there would be no effective whipping. Without whipping, there would be no stable parliamentary parties. Without parties, representative democracy would be impossible.
Then what? Ministers, insecure in their jobs, would have to spend so much time cajoling other MPs that their Whitehall offices would be run without them.
If you accept that argument then you have to concede that Mr Willetts and Andrew Mitchell were not subverting the real constitution, based on ministerial power, but were in fact acting as its true guardians.
Let us push this to its logical conclusion. Without their kind - the Dyno-rod operatives of British politics - Westminster would seize up. Just as diplomats are sent abroad to lie for their country, whips are obliged to do the same thing by the banks of the Thames - dirty work, Carruthers, but someone has to do it. This would happen under Labour too.
Why then all the fuss? Is it merely that Quentin Davies, the Tory backbencher who gave Willetts such a tough time, is a disappointed man - and that Dale Campbell-Savours, the leading Labour inquisitor, is a natural born troublemaker?
Davies is certainly a staunch pro-European, who badly wanted to be a minister but didn't win the kind of promotion Willetts did; he was the only Tory MP to vote against the government line on the Scott Report debate; and he is now the reproving BBC/ITN standby "pro-Brussels" Tory. Indeed, the mere fact that Davies is on the standards and privileges committee refutes any notion of an all-powerful whips' office.
Well, there are no pure motives in politics. But if you are tempted by the argument as laid out so far, try to imagine it being defended in public by any Conservative MP - not in general terms, which is hard enough, but in the specifics of the cash-for-questions affair.
It would have to run something like this:
"One of my colleagues, Neil Hamilton, took money from a businessman to ask questions in Parliament. This was a bad business, though hardly unique. A newspaper got hold of the story, because the business feller sneaked. It was going to be very embarrassing for the PM. So the Government decided to hide it from you by privately fixing a committee.
"That committee pretends to be staunchly independent - just as I do - but really, of course, most of us are trying to make our way in the world. So the chats between the whips and some of its members went on. Then, dammit, these also became public because Willetts wrote a note, which was passed to The Guardian ahead of court proceedings. So then another committee had to sit, and pretend to be cross. Naughty Willetts! In fact, of course, we are all on his side. This `sovereignty of Parliament' business is a bit of sham. We bang on about it when we are having a go about Europe But none of us takes it seriously."
Such appalling frankness is impossible to imagine. The most cynical MP could not openly admit that keeping in with the Government and its whips matters more than defending Parliament's independence. There is still some residual belief in the honour of the House - a corporate sense of shame. While that is true, there is hope.
So what now? There is no point in issuing journalistic edicts against sin and in favour of political chastity. Whatever the rulebook says, there will be party whipping; and where there is whipping, there will be unsavoury conversations, deals and private offers. Always. Put a microphone above the urinals and a journalist in every broom-cupboard --and you still would not stamp it out.
That's politics. But having politics, however grimy round the edges, is vastly better than not having politics. It is important not to let the perfect be the enemy of the tolerable. The Commons can still hold the line against excessive government intrusion by pouncing and expressing anger whenever a minister is caught out, and demanding sanctions, including suspension. (This would wipe out the current Government's majority, but that is not as great an issue as it might seem: the Ulster Unionists will support them for the time being.)
It could go further than it has in the past. If MPs are really worried about their sliding public image, then they need to restoke their indignation about being put upon and lied to by Power's smooth servants. Where a Quentin Davies and a Dale Campbell-Savours have led, many more can follow; and they would be doing Parliament itself a service. Now, you may say, this proposed angry reassertion of its formal rules would be more than synthetic - it would be hypocritical. So am I advocating hypocrisy?
Yes, indeed. Without a little of the grease of hypocrisy, no system of representative democracy can function. This week's events add up to an exercise in necessary hypocrisy. It helps to police the narrow line between the Government fighting in the Commons to get its way and the Government treating the Commons with contempt. It is, in short, an excellent show- trial.