Joseph Fletcher, an Anglican theologian, developed situation ethics in the 1960s after critiquing legalism and antinomianism. Legalism is the belief that there are fixed moral laws that must always be obeyed. Antinomianism is the belief that there are no fixed moral principles and that ethics should be spontaneous.

Fletcher believed that neither legalism nor antinomianism provided a sound basis for ethics and advocated "situationism" as a compromise. His book, Situation Ethics, was the centerpiece of his critique and founded much of the modern situation ethics movement.

According to Fletcher, decision-making should be based on the circumstances of a particular situation, and not on fixed law. He believed that truth is relative and that love is the only absolute. Thus, he believed that as long as love is the intention, the end justifies the means.

Ironically, Fletcher claims he founded his model on a biblical statement found in 1 John 4:8: "God is love." Yet he apparently didn't realize that the same book says commandment keeping shows our love for God (1 John 5:3) and that God never approves of law breaking. Indeed, such conduct is sinful (1 John 3:4).

What eventually happened to Fletcher? His conclusion that God's Word wasn't enough to guide decision-making led him to become an avid supporter of euthanasia and abortion. He died in 1991 an atheist.