If so, then we are all mad -- for much empirical research demonstrates the endless ways in which all of us behave irrationally practically all the time ... (see best-selling work by Dan Arielly, for example!) ... And anyway, surely we are familiar with at least the literary/cinematic stereotype of the absolutely even-keeled, coldly rational/logical/calculating supervillain who is simply MAD in his desire to conquer the world etc.... I don't know if there ever have been individuals fitting that description but the sheer fact that it's conceivable suggests that we conceive of "madness" in terms other than "irrationality" .... And finally, perhaps, "irrationality" is a matter of how well the means we pursue are apt to obtain the ends we pursue -- but madness (at least in that stereotype case) is a function only of the status of the ends themselves .... so a mad "end" might be pursued very rationally, or a sane "end" might be pursued very irrationally ....

hope that's useful!
ap