So... I made my argument yesterday about the difference between being rational and being reasonable.
Today's xkcd comic, coincidentally, covers in some respects the same territory.
...okay, so it's almost certainly just a coincidence. I'm reasonably sure that the few dozen hits I get a day don't include the greatness that is Randall Monroe. Could confirm or deny with an IP trace, but I'm feeling a little bit lazy this morning. Too lazy to webstalk.
Anyways, here's the comic (sans mouseover text, since I can only embed the image).
Same starting point, though played for laughs rather than philosophy.