- Marx's definition of Productive Labour is specific to the analysis of capitalism, i.e. it is specific to political economy. Ethics or moral philosophy might have a totally different concept of what is productive or unproductive.
- Labour might produce value in the form of a material product such as a coat, or of an immaterial product, such as a performance by a singer or actor, or a labour service. It is not the nature of the product, which determines whether it is productive or unproductive labour, but its relation to capital, i.e. whether it produces surplus value.
- A buyer of a material product such as a coat, like the purchaser of an immaterial product, such as a labour service provided by a cook or a prostitute, exchanges an amount of value in the form of money for that product, only because what they acquire with that money is an equal value, represented by the product of that labour.
- It is not the nature of the product, or type of labour undertaken, or what purpose the product is put to, i.e. what form of consumption it results in, that determines whether the labour is productive, but only whether it produces surplus value. The labour of a prostitute creates value in so far as it is labour that provides utility to the consumer of the labour service provided. If that labour service is provided directly to the consumer, it produces no surplus value, and is not productive. If the prostitute sells their labour-power to a brothel keeper, who then sells the labour-service of the prostitute to clients, and in the process derives a surplus value, then the labour is productive. The surplus value derives from the fact that the prostitute does not sell the product of their labour to the brothel keeper, but their labour-power, the capacity to perform such labour. The value of the product of the labour sold by the brothel keeper to clients, is greater than the value of the labour-power sold by the prostitute to the brothel keeper.
- Marx's definition of productive labour is the same as the first definition provided by Adam Smith. However, Smith in keeping with the duality that runs throughout his analysis of value, has a second incorrect definition of productive labour, which slips back into Physiocratic conceptions of productive labour as only that which produces material commodities. In order to sustain his position, Smith also slips into a definition of productive labour that is merely productive of value rather than surplus value. Marx's extensive analysis and theory of productive labour, cuts through this confusion contained in Smith's theory.