or those of you still depressed by that glimpse of political hell offered by the seven-headed beast last Thursday night, here is a cheering thought: that may have been the summit of its glory. I do realise how much this sounds like wishful thinking but I am beginning to believe that the Great Fragmentation might have reached its apotheosis in that spectacle, which was rather absurdly called a “debate”.

The outsiders may have had their 15 minutes of triumph but the overall result looked like an amateur hour of pointless conflict, wild assertion and unanswered challenges. It was, to borrow the Tories’ favourite epithet, chaos. But this shout-up, in which everybody was talking at crosspurposes, is not my main reason for expecting the electorate to conclude that maybe being governed by a multi-party mash-up is not a great idea.

The week also saw a series of events – or rather a single event with a series of consequences – that really did hint at the return of the traditional polarity of party politics.

It began with that starkly worded letter to The Daily Telegraph from more than 100 business leaders, which delivered a chilling warning about the danger Labour represented to the economic recovery. Left to stand, that might not have disrupted the campaign themes of the major parties all that much. But Labour decided not to let it lie. It retorted with a message that played precisely into the hands of those Tory strategists who were benefiting from the business leaders’ statement. Instead of trying to counter the argument that his policies would be anti-business (and therefore anti-growth), Ed Miliband upped the ante and made an attack on business, depicting it as the merciless exploiter of the worker. His assault on zero-hours contracts (or, in other words, a flexible labour force) put him, and party politics, squarely back on to the old class-war formula that some of us are old enough to remember.

Yes, children, back in the days before Thatcherism caused the Labour Party to reinvent itself and learn to love capitalism, there were major national leaders who talked like this all the time. What was good for Business must be bad for the Workers because the interests of these two classes of people were fixed, immutable and indelibly opposed to one another. Now “zero-hours contracts” is just the legalised name for casual labour, which has been a feature of the building, retail and catering industries for generations. The capacity that they offer to companies to adapt instantly to changing needs and circumstances is the envy of many of our economically stagnating EU partners. In Italy, it is said that hiring somebody is like marrying him – so permanent and insoluble is the bond that it is virtually impossible to cut employment costs when your business is going under. Whereas, in the UK, not only do businesses survive that would otherwise fail but there are opportunities for paid employment for thousands of people who would otherwise get no experience of working life at all. But leaving the specific arguments for and against flexible labour markets aside, it was the tone of the Labour retaliation that was of such crucial importance to the future of our politics.

Miliband was returning his party to prehistory: not just pre-Blair but pre-Kinnock. This was the language of Michael Foot, of the great sectarian wars of the early Eighties in which the feet of the workers were set in the concrete of their hereditary circumstances, and to aspire to escape from the limitations of your background was to be a class traitor. Needless to say, Miliband wouldn’t put it quite like that now. The vocabulary in which these things are discussed has moved on. But the conceptual framework was still there, perfectly intact: the bosses are the enemy (or, as he once put it, the “predators”) whose only motivation was to suck the lifeblood out of the helpless, profit-fodder they employed and then discard the desiccated remains when they were of no further use. (In fact, anyone who has run a successful business will testify that a loyal, well-treated workforce is the most valuable asset to enterprise.)

That’s it, then. At least for the duration of the present electoral emergency, we can forget the consensus that we thought we had reached in the mid-Nineties. Labour has mobilised full-on class enmity. No more Mr Nice Guy. No more agreement about the value of free markets and the social mobility which they enable.

I personally welcome this – and not just because it makes Labour likely to lose support. Consensus is the enemy of freedom: it is only by being offered a choice between genuine alternatives that the voters have actual power. Engagement with the democratic process falls away when the electorate is faced with identical packages under nominally different brand names. So bring it on. Let’s have this important, invigorating argument all over again.

But if it is to have the same outcome – if the people are once again to be persuaded that business is not their eternal enemy and that wealth creation is a social good – then we must see it through with the kind of bravura confidence that our side displayed way back in Class War I. David Cameron must marshal the moral case for capitalism, which, given the history of the last century, should not be difficult. This isn’t about Fat Cats: it’s about the life chances of everyone. Free-market economics has delivered mass prosperity and financial security on a scale that is unprecedented in human history.

As well as securing advantages for the majority that were once experienced only by the privileged few – the ownership of property, self-determination, and freedom from basic want – it has unleashed the potential of millions of people in a way that was undreamt of in earlier eras. Freemarket societies are more innovative and more personally liberating than any other form of economic organisation.

In other words, it is not necessary – indeed, it is quite wrong – for the Conservatives to assume that they must present themselves as the practical (but hard-hearted) party, thereby casting Labour as the sympathetic (but wrongheaded) one. There is always a risk that voters will opt for heart over head in a fit of confused sentimentality.

So it is absolutely necessary to repeat this over and over again: choosing to preserve the free-market system is a humane decision. The liberty it offers is the proper fulfilment of adult life that involves accepting personal responsibility – and that is what we should want for as many people as possible. For those who are incapable of making use of the opportunities it makes available, or who fall into difficulties, there must of course be protection and care: that is part of the concept of responsibility that full adulthood implies. (This is known as decency or “doing the right thing”, and is pretty much universally understood.) But that is very different from the hereditary helplessness that the ideological Left attributes to an entire class of people on the assumption that their fate is permanently fixed.

This is the heart of it: the principle of class war implies that you expect people to remain in their camps, fighting a permanent battle of attrition. The Conservatives must not be afraid to defend the opposite: movement, mobility, change and adaptation. Those are the things that create a truly open society. It isn’t simply a question of being pro or anti-business but of being in favour of new possibilities and life chances.

We have had this argument before within living memory. It looks as if we are going to have it once more. It was illuminating and exhilarating the first time round and could be again if it is entered with the same degree of lucidity and conviction.