Speaking of Malthus....................

Malthus's theory had a quite simple statistical basis.  Without restraints, the reproductive forces in nature increased in geometrical progression.  Food supplies, by contrast, increased only in arithmetical progression.  At the rate we were going, he argued, the number of mouths would double every twenty-five years.  The amount of food would rise only marginally.  The result:  mass starvation, famine, pestilence, war, and every kind of catastrophe.
     Malthus's aim was to discourage charity and reform the existing poor laws, which, he argued, encouraged the destitute to breed and so aggravate the problem.  That was not Darwin's concern.  What struck him was the contrast between geometrical progression (breeding) and arithmetical progression (food supplies).  Not being a mathematician, he did not check the reasoning and accuracy behind Malthus's law.  Was he not a Cambridge wrangler?  In fact, Malthus's law was nonsense.  He did not prove it.  He stated it.  What strikes one reading Malthus is the lack of hard evidence throughout.
-Paul Johnson,  Darwin:  Portrait of a Genius