The ABM Issue in the Senate, 1968–1970: The Importance of Ideology

Three hypotheses suggesting why senators might adopt or change positions on such an issue as the ABM are compared. The empirical analysis clearly substantiates the contention that position reflects ideology, not party commitment or potential state economic benefits. Furthermore, the influence of ideology is seen to have grown more apparent each year the issue was contested in the Senate. Virtually all the senators who changed position between 1968 and 1970 had initial positions that did not accord with their ideology, and they moved so as to bring them in accord. Virtually all those senators whose initial position was in accord with their ideology maintained that position.