Is reality optional? : and other essays / Thomas Sowell. Sowell, Thomas, 1930- Social problems. Social values. Reality. Civilization, Modern 20th century. HM73 .S686 1993 301 20 SOI Contains previously published essays. Stanford, Calif. : Hoover Institution Press, c1993. c1993. 1993 Text x, 192 p. ; eng Hoover Institution Press publication ; no. 418 Hoover Institution Press publication ; 418.