So the labour theory of value does not explain the source of profit. Consequently the law of the declining rate of profit fails too, for that starts from the assumption that only labour can create value. Does it also follow that workers are not even exploited? Here opinions differ. Some have argued that once the labour theory of value falls there is no basis left for the charge that workers are exploited. But others believe that there is still a strong argument to be made. Suppose you work eight hours a day. Imagine that there is nothing you can buy with your wage that took more than a total of four hours to make. There appears, then, a clear sense in which you have lost something in this. We can say, surely, that there has been an unequal exchange of labour. Someone else is getting the benefit of some of your labour. The truth of this does not depend on any particular theory of value or profit.

Now, is it true that workers under capitalism are exploited in this sense? For the affluent workers of developed economies, probably not. Most Western workers can command more hours of labour than they have to work; provided it is the labour of Third World workers. A day’s Western wages might buy you weeks of an Indian or Chinese labourer’s work. These are the truly exploited (although who is the exploiter is a more subtle question); and often work in exactly the condition Marx wrote about in the England of the mid-nineteenth century.