So this guy thinks he knows the full range of ideas, and that it's not possible that someone has thought of something he hasn't, that might just be good enough

So this guy thinks he knows the full range of ideas, and that it's not possible that someone has thought of something he hasn't, that might just be good enough to warrant investment. "I must confess that a man is guilty of unpardonable arrogance who concludes, because an argument has escaped his own investigation, that therefore it does not really exist."--David Hume