Thomas Robert Malthus was a British scholar who lived from 1766 to 1834. His works focused on the economic growth of society and how subsistence living eventually led to famine or disease, thus controlling population growth.
Malthus, at the time, was a voice of dissension in the popular notion that society was growing towards a Utopian ideal. He believed that humanity could never take serious steps towards utopia because it expands too rapidly; in his view, childbirth outpaced the production and/or gathering of goods necessary to keep everyone alive.
The "traditional society" was one in which each person worked towards the betterment of all, but in which there was no chance of famine or plague. The notion that humanity was free to "be fruitful and multiply" was one that Malthus disagreed with; he believed that at every point where progress can be made, humanity's arrogance leads directly to a thinning of the herd, either by lack of resources, disease, or war. Malthus believed that humanity should instead restrain themselves from over-breeding, and a smaller society with fewer people -- and thus fewer strains on the economy -- could take larger steps towards the eventual Utopian ideal, even if they could never truly reach it.