Roko on artificial intelligence in his latest Good article:

Computers that can behave intelligently and rewrite their own code could be dangerous in ways that are not at all obvious to their creators. The codebreaker scenario outlined above is an example of a hard takeoff event—where a smarter-than-human AI quickly (in a matter of hours or months) takes control of the entire world and utilizes all the resources in the world to achieve whatever goal it has been programmed with. Whether such a hard-takeoff scenario is likely has been disputed; however, the ability of a smarter-than-human intelligence to surprise us shouldn’t be underestimated.

In the next Good piece we will be positive for a change — I will summarize the potential benefits of successful friendly AI.