1. Russia is stable. But maybe not. We tend to forget that Russia, like the USSR it was a part of, is an empire composed of a dominant ethnic minority and subordinate nationalities and ethnicities. It could be that the breakup of the USSR is just the beginning. Further disintegration is a possibility, and a harsh economic blow might do the trick.

2. China will respect the borders of its neighbors. But maybe not. If the US is forced to give up its world-straddling presence, it will leave a power vacuum which Japan and the EU are uninterested in filling, and Russia is incapable of it. What would tempt China to go adventuring? The collapse of Russia into warring factions might do the trick. Siberia, which isn't Russian but a territory occupied by Russian conquerors, would be a glorious prize for the Chinese Revolution. It would provide vast resources to a populous nation that sorely needs them. Admittedly, there's the little problem of nukes to worry about, but if Russia is plunged into a civil war, China might be able to figure a way to do it without triggering a holocaust.

3. Al-Queda Hates Our Freedoms, which is why they attacked us. But maybe not. It could be that their whole objective was to encourage us into adventures against Muslim nations, which in turn would stoke Muslim dissatisfaction with secular government in the region, dissatisfaction with borders drawn by outsiders, and, of course, dissatisfaction with meddling outsiders. Like anyone else, Muslims want to chart their own destinies, and to be saddled with puppet governments and forced secularism and foreign occupying powers is a boil on their butt. The long-range objective of this strategy? To throw down secular governments and stand up a new united, fundamentalist Caliphate. And swat Israel, but that might only be an afterthought. Israel is a symptom of Muslim weakness. Muslim strength is the real goal.

4. Climate Change Won't Be Catastrophic. But maybe not. I'm turning Jacob's approach to this one on its head. The conventional wisdom - not the view held by climatologists and biologists, but the general public - is that climate change is slow. It's mostly affecting cold places. Heck, some places may even change for the better. So maybe it won't be so bad. Nobody's talking about the seas boiling, after all. There is so much science contradicting this uninformed viewpoint that it's hard to know where to begin. I think I'll just make one point and leave it. That point is this: there is no doubt, absolutely none, that a mass extinction is underway on a scale seen only perhaps 4 or 5 times before in the Earth's geological history. As a species perched uncomfortably atop an ever-shrinking pyramid of Earth life, we will be exposed and vulnerable.

I'll close with a comment about Jacob's challenging the common wisdom about fossil fuels. He's right - sort of. There are hundreds of years of fossil fuels still in the ground at current burn rates. Cheap, sweet crude will be the first to become scarce, it appears. But there's lots of other fossil fuels. Especially methane and coal. The bottom line is that we could keep burning for a long, long time if we thought it was smart to do. The question we should be asking is not, are we running out? But, is it smart to keep burning the stuff? Sure it is, if you ignore what science is telling us about climate change, mass extinctions, and the effect of pollution on our health (and health care costs). It doesn't look so smart if you factor those things in.

We have not yet moved away from fossil fuels because we have no real economically-feasible alternatives to base an industrial civilization on (yet). Cheap energy is not just a nice-to-have for an industrial civilization, it's the starting point for it. Choosing an expensive alternative means serious retrenchment: less transportation, less manufacturing, less everything. That's unappealing; it's hard enough to create jobs for everyone without reverting to a less industrialized state. So I don't think we will make much headway on getting off of fossil fuels until equally cheap alternatives are widely available.

We'd better get cracking on that.