He saw positive checks to population growth as being any causes that contributed to the shortening of human lifespans. He included in this category poor living and working conditions which might give rise to low resistance to disease, as well as more obvious factors such as disease itself, war, and famine. Some of the conclusions that can be drawn from Malthus's ideas thus have obvious political connotations and this partly accounts for the interest in his writings and possibly also the misrepresentation of some of his ideas by authors such as Cobbett, the famous early English radical. Some later writers modified his ideas, suggesting, for example, strong government action to ensure later marriages. Others did not accept the view that birth control should be forbidden after marriage, and one group in particular, called the Malthusian League, strongly argued the case for birth control, though this was contrary to the principles of conduct which Malthus himself advocated.
The influence of Malthus' theories was substantial. Among others, he developed a theory of demand-supply mismatches which he called "gluts." Considered ridiculous at the time, as it violated Say 's Law which basically stated that supply creates its own demand, his theory was a precursor to later theories about the Great Depression, and to the works of admirer and economist John Maynard Keynes . Malthus has also been admired by, and has influenced, a number of other notable economists, including David Ricardo with whom he maintained a long lasting friendship but opposite thinking on economics.