Final answer:
Malthus believed population growth is checked by limited subsistence leading to catastrophes, while Marx focused on class struggle within the capitalist system, which includes but is not centered on struggle for subsistence.
Step-by-step explanation:
According to Harvey, the way Thomas Malthus and Karl Marx differ in their views of subsistence is centered around their perspectives on population growth and economic theories. Malthus believed that population growth was naturally limited by the means of subsistence, predicting a 'Malthusian trap' where population would outpace food production, leading to catastrophe through war, famine, and disease. Marx, on the other hand, focused more on the societal impact of capitalism and class struggles, with subsistence aspects tied into his broader critique of capitalist production modes but not as a primary focus on population control.
Malthus's outlook on subsistence and population emphasized natural checks on growth, believing that as the population increases, resources like food and water would become insufficient, which in turn would control the population through 'Malthusian disasters.' Contrarily, Marx's analysis of society and subsistence was embedded in his deep investigation of class relations and the mechanics of capitalism, which can include struggles over resources but is not reduced to population checks through scarcity in the same way as Malthus described.