My point being that you can be much much more destructive by blowing up the energy source of a space-based weapon on Earth than using it to power a kinetic weapon, and that in any case there's no reason to think we will be building spacecraft that are a danger to anything on Earth as anything but a carrier of radiological/etc payloads or a destroyer of launch facilities during failures in the forseeable future. Upmass is very expensive.
EDIT Relativistic kill vehicles, for example, are both so far beyond or ken and useful only over such long distances (seriously, an ICBM is more surprising over distances smaller than several times the size of the entire solar system and I don't even know how many orders of magnitude simpler than the infrastructure required to make one) that I fail to see the point of worrying about them. The only space-based weapon that could be a problem that I can think about is identifying some 100 meter wide rock that is set to just miss the earth a century hence and giving it a 1 m/s push to change that fact (which according to my calculations would require an ion engine using the equivalent amount of energy to a whole day's worth of the entire world's electricity consumption, nuclear bombardment, or messing with its interaction with sunlight drastically).
Rather than interpreting "space-based weapon" as the first thing that comes in to mind and saying that's stupid, why don't you think about it for five minutes? Or look it up.
TYLER COWEN: Peter, tell me something that’s true that everyone agrees with you on.
PETER THIEL: Well there are lots of things that are true that everyone agrees with me on. I think for example even this idea that the university system is somewhat screwed up and somewhat broken at this point....You know, the ideas that are really controversial are the ones I don’t even want to tell you. I want to be more careful than that. I gave you these halfway, in-between ideas that are a little bit edgier.
But I will also go a little bit out on a limb: I think the monopoly idea, that the goal of every successful business is to have a monopoly, that’s on the border of what I want to say. But the really good ideas are way more dangerous than that.
Full interview. HT Quora.
What are some good answers and your guess as to his answer? Please exclude issues relating to race and gender.