I need to win an argument about fixed gears

Just bring out that Desgrange (Tour De France founder) quote:

*I still feel that variable gears are only for people over forty-five. *
*Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? *
*We are getting soft...As for me, give me a fixed gear! *

Although, to be fair, gears are probably better in 90% of situations.

Don't. Desgrange was an arsehole.