Well, consider that a few places have suffered catastrophic failure due to overpopulation since Malthus. These were politically distinct and mismanaged, but still: even though lots of people had guns and the will to use it, they weren't able to account for the externalities of others. As climate changes, the fact that we have defended borders is going to mean that overpopulation will become important for citizens that are prevented from migrating out of famine regions. We also have to ask whether we've denied Malthus by finding new resources or if we'd just increased the scope of our resource consumption. We're at a stage of development now where almost all food production is entirely dependent upon oil; so it's obviously limited by oil or other fossil fuels. However, most farms are losing topsoil every year due to the way they're farmed: this might not matter where there is lots of topsoil, but it matters where there is 'some' topsoil. The number of fishing stocks that have become nonrecoverable have only increased since Malthus, and we're now at the point where 75% of fish stocks are 'threatened' or worse. While building to the current population, we've threatened (or worse) 75% of fish stocks: so the trend is clearly unsustainable. A huge number of regions have their aquifers going down; few are going up. This means that the 'free water' that we're currently using is going to become very expensive. Even Israel, which uses water rather carefully, has lowering aquifers. And their aquifers are becoming increasingly polluted. Finally, the wetlands that naturally clean water before they drain into aquifers are being taken away. So, soil, fish, water and ultimately fossil fuels are all being depleted. It doesn't really matter if you can poo-pooh one or two of those concerns away, either, because they're all risk factors in over-population. And, finally, as a great indicator: in wealthy countries, the amount of money a poor person has to spend to get a healthy diet continues to increase as a percentage of their income. Even in Canada, the poor are having a harder time eating healthy. If that's a trend, it's a scary trend.