William Bradford Reynolds was influenced by the social science evidence on affirmative action, but his approach was shaped primarily by his understanding of the meaning of the Civil Rights Act. Many liberals had embraced disparate impact and benign preferences during a time of prosperity, a time when per capita income was increasing annually. When Griggs was decided in 1971, few Americans were concerned about the cost of affirmative action. During the Reagan years civil rights lawyers and some liberal economists argued that affirmative action was responsible for some of the job advancement of members of minority groups. Thomas Sowell of the Hoover Institution at Stanford University acknowledged that "the notion that the Civil Rights Act and 'affirmative action' have had a dramatic impact on the economic progress of minorities has become part of the folklore of the land". The black economist Thomas Sowell observed that affirmative action "has meant mutually canceling incentives to hire and not to hire".