Often in arguments about the future resolutions of apparently intractable problems, vague references to science or human intelligence to solve problems, or specific technological fixes are invoked that would neatly resolve said intractable problem.
Too many times the fix is chosen in a way that most closes the argument rather than being the most likely path that technology (or other aspects of humanity) will take in the resolving the problem or the opposite. Technology, science and intelligence are just as capable of enabling "problems" to be extended in time. What can be imagined to be solved by an improbable specific technology, could more likely be attacked by a sequence of more probable ones.
So when someone says that a space vehicle engine will be found that can take us directly from earth to Mars, or that peoples intelligence will be put to eradicating wars forever, or that we could live cheaply as brains in tanks, I would like a believable sequence of events or pathway that has a finite possibility.