Alex Tabarrok Asks a Question...: Brad, not being funny here, but have you read Marx? Alex Tabarrok has an excuse for not knowing the first thing about him, but you teach History of Political Economy!
Marx would not have been hypocritical to have bought vegetables in a market and surplus-value has nothing to do with it. Marx's view of commodity markets did not differ materially from Adam Smith. Marx might have been considered hypocritical if he had employed large amounts of labour ... but ...
Engels actually did! It is not exactly an obscure point about Engels that he was a factory owner. Marx and Engels wrote voluminously about the specific point at issue, and they specifically and repeatedly said that they thought the rules were suboptimal (to say the least), but that at the point in history where they found themselves, there was no point in trying other than to act within them, and to work to create another possible society. Historical materialism is also not an obscure point about Marxism!
Furthermore, the conflict between and need to reconcile and synthesis differing and contradictory principles, under the name of "dialectic" is also not exactly an obscure part of Marx's philosophy.
I am unconvinced. The problem is that Marx is trying to have his surplus-value cake and eat it too. He wants, on the one hand, to claim to simply be a positive social scientist projecting out the laws of historical development in a value-neutral manner--describing, not condemning. He wants, on the other hand, for his descriptions to carry labels like "exploitation." I don't think it works. But Marx needs both elements. If, after all, the current system is not unjust, why work so hard to change it? Why not let peaceful historical evolution take its course?
Barmen & Engels is a whole additional can of worms all on its own...