Definition of "necessarianism"

Scholars working on Joseph Priestley have begun to take a proper measure of his philosophical position, known as “necessarianism,” a psychological determinism based on the teachings of the midcentury physician and theologian David Hartley—with, in Priestley′s own case, the addition of materialism. To its enemies, necessarianism seemed rank fatalism, but its adherents found that it both explained the evils about them and offered a sovereign remedy (generally through one or another variety of education) to resolve them and bring mankind to perfection.

1995, Denis G. Paz, Nineteenth-Century English Religious Traditions: Retrospect and Prospect, page 106

While not acceptable to all Unitarians, the philosophical determinism known as Necessarianism, identified with Hartley and Priestley, also proved persuasive to many, both ministers and laymen.

2000, R. K. Webb, “6: Miracles in English Unitarian Thought”, in Mark S. Micale, Robert L. Dietle, editors, Enlightenment, Passion, Modernity: Historical Essays in European Thought and Culture, page 114

To cut a long story short, this led to the emergence of a new form of necessarianism. People are conditioned to behave as they do, so freedom is an illusion. This form of necessarianism may be called ‘behaviourist necessarianism’.

2001, Alexander Crombie, An Essay on Philosophical Necessity, page number not shown