Malthusian thinking really should be considered debunked by the developments in the world since the Industrial Revolution. Prior to that, it was believed that a rise in population levels would always be accompanied by a fall in living standards since the same amount of resources were distributed among more people.
As the link's graph illustrates, however, the world's population has surged dramatically since the end of the Second World War. And in that time, global prosperity has also improved dramatically. In fact, recently, the global population boom is beginning to slow down. Many developed countries have zero or negative growth, and the big boomers of the 80s and 90s (India and China) are also starting to rein in their pop growth (China more successfully). Despite the massive amount of population growth in India and China, the per capita wealth of these nations has also improved, despite the govt's often backward and corrupt policies.
There are plenty of doom-mongers out there, including respected analysts, who have been banging the unsustainable growth drum for the better part of two decades now. They haven't been proved right yet, and they won't be.