The party then has two choices. It could try to stick to its position, in which case it would be battered like a boxer on the ropes. Or it could announce that it has thought again. In that case, general mockery would ensue. Every opposition spokesman would be taunted: which of his propositions was next for rethinking? On policy, an opposition which writes from the hip will be kicked in the backside.
Some of David Davis's senior supporters are aware of this. David Willetts has gently pointed out the unwisdom of trying to make tax policy now for the next decade. David Davis is not stupid. He must realise that this will do him damage among thoughtful Tories. Mr Davis is not interested in thoughtful Tories; that is the key to the Tory leadership campaign, and the true divisions. They are not about ideology or policy; they are cultural.
A lot of instinctive Tories are fed up with the direction that modern Britain has taken. Although it might seem easy to dismiss such characters as troglodytes, they have more of a case than their facile critics would concede. It is based on three policy areas: Europe, crime, and immigration. On each, these dissident Tories believe that they were right all along. They know that behind the reassuring propaganda about free trade, the foreigners - and the Foreign Office - were always plotting to create a federal Europe.
They knew that a more liberal treatment of criminals would merely encourage more crime. They predicted that the abolition of the death penalty would result in a great increase in gun crime, and murder. They also predicted that large-scale coloured immigration would change the character of our cities, while creating intractable social problems.
On the basis of the evidence, they are not about to admit that they have been proved wrong. Any intellectually honest liberal ought to concede that the troglodytic Tories did make a realistic assessment of the complexities of change.
David Cameron knows that some of the changes are irreversible. We can fight for Britain's rights in Europe and resist any further federalist encroachments, but we are not going to leave the EU, and we will remain net contributors.
We can impose tighter controls on future immigration, and we must deal with the scandal of illegal immigrants. However, the character of some of our cities has changed, irrevocably. There is no alternative, we have to work with the new communities to help them to assimilate. There is nothing we can do to reduce murder and gun crime rates to 1950s levels. There are measures that could be taken, such as restoring a backbone of leadership throughout all police forces; but there is no use indulging in fantasies about bringing back the death penalty.
Tough-minded Toryism is both necessary and desirable; but that is not a matter of strutting, lapel-tugging and sloganising. Tough-mindedness means wrestling with difficulties, not retreating into fantasy.
David Davis arrived at the Tories' party conference thinking that he had almost wrapped up the leadership. He was rapidly disillusioned. Since then he has tried to conceal his bewilderment - plus his bitterness - and recover from his reverses by falling back on what he hopes is his base: those Tories who want to stop modern Britain so that they can get off. In the middle of last week, that seemed to be yielding benefits. Fortunately for the Tory party, this was short-lived.
Over four or five years, a Cameron government could achieve as much as a sensible, real-world right-winger could realistically expect. Apart from being electorally inconceivable, a Davis government would be much less effective. In Britain today, it requires intellectual self-confidence to be a successful right-winger. Mr Cameron possesses that attribute. Mr Davis does not: he knows himself too well.
Wise Tories may well regret the social changes of the past 40 years. The only sensible attitude is to choose a leader who would manage them; not one who would start by opposing them all, and end up by surrendering.
David Cameron has often been described as moderniser: not an unfair account of his opinions. By "modernising", Mr Cameron would not mean an open-ended acceptance of a metropolitan trendy agenda. He would simply mean that if the Tory party wishes to create the Britain that it would like to see, it must start by coming to terms with Britain as it is.