A teoria do valor-trabalho

Is the Marxian labour theory of value correct?, por Paul Cockshott (Though Cowards Flinch):

Then in the 1990s Marxian economists started to apply the normal scientific method to the labour theory of value, for example here or here or there. What did they find?


They found that the predictions of Marx and before him Ricardo had been spot on. Market prices were actually correlated with labour values to the remarkable degree of 95% or more. That meant that 95% of the variation in the prices of goods is explained by the labour cost of making them.

More strikingly, it was shown that the more capital intensive an industry was, the lower was its rate of profit. This is exactly what one would expect if labour rather than capital was the sole source of value. This explains why railway projects like the Channel Tunnel are almost always unprofitable. They involve a lot of capital but employ little labour on which to make a profit.

Diga-se que o fenomeno dos sectores mais capital intensivos terem uma menor taxa de lucro também pode ser explicado recorrendo às ferramentas da micro-economia neo-clássica: como os sectores capital-intensivos tendem a ter maiores custos fixos (o custo de construir o tunel sobre a Mancha é sempre o mesmo quer passem por lá 1 ou 10.000 carros); como (segundo os neo-clássicos) os preços tendem a ser determinados pelos custos variáveis (mais exactamente, pelo custo marginal), quanto maiores forem os custos fixos, menor a margem [valor das vendas] - [total dos custos].

Ainda outro ponto:

Once it is realised that the determination of value by labour is a well proven scientific theory, then Marx’s analysis of exploitation follows – with all sorts of disturbing moral consequences for the established order.

Para falar a verdade, não sei se o raciocinio "o preço das mercadorias tende a ser proporcional ao trabalho necessário para as produzir, logo os capitalistas exploram os trabalhadores" fará grande sentido.