The SciencesMetamagical Themas, June 1983The calculus of cooperation is tested through a lotteryBy Douglas R. Hofstadter on June 1, 1983AdvertisementABOUT THE AUTHOR(S)Recent Articles by Douglas R. HofstadterMetamagical ThemasMetamagical Themas, May 1983Metamagical Themas, April 1983