Editing Joseph Priestley (section)

===Materialist philosopher===
{{further|Joseph Priestley and Dissent}}

Priestley wrote his most important philosophical works during his years with Lord Shelburne. In a series of major [[Metaphysics|metaphysical]] texts published between 1774 and 1780—''An Examination of Dr. Reid's Inquiry into the Human Mind'' (1774), ''Hartley's Theory of the Human Mind on the Principle of the Association of Ideas'' (1775), ''[[Disquisitions relating to Matter and Spirit]]'' (1777), ''[[The Doctrine of Philosophical Necessity Illustrated]]'' (1777), and ''[[Letters to a Philosophical Unbeliever]]'' (1780)—he argues for a philosophy that incorporates four concepts: [[determinism]], [[materialism]], [[causality|causation]], and [[necessitarianism]]. By studying the natural world, he argued, people would learn how to become more compassionate, happy, and prosperous.<ref>McEvoy and McGuire, 326–27; Tapper, 316.</ref>

[[File:PriestleyMatterSpirit.png|thumb|upright|alt=Page reads: "Disquisitions relating to Matter and Spirit. To which is added, The History of the Philosophical Doctrine concerning the Origin of the Soul, and the Nature of Matter; with its Influence on Christianity, especially with Respect to the Doctrine of the Pre-existence of Christ."|By 1782, at least a dozen hostile refutations were published to ''[[Disquisitions relating to Matter and Spirit]]'', and Priestley was branded an [[atheist]].<ref>Schofield (2004), 72.</ref>]] 
Priestley strongly suggested that there is no [[Dualism (philosophy of mind)|mind-body duality]], and put forth a materialist philosophy in these works; that is, one founded on the principle that everything in the universe is made of matter that we can perceive. He also contended that discussing the soul is impossible because it is made of a divine substance, and humanity cannot perceive the divine. Despite his separation of the divine from the mortal, this position shocked and angered many of his readers, who believed that such a duality was necessary for the [[Soul (spirit)|soul]] to exist.<ref>Schofield (2004), 59–76; Gibbs, 99–100; Holt, 112–24; McEvoy and McGuire, 333–34.</ref>

Responding to [[Baron d'Holbach]]'s ''[[The System of Nature|Système de la Nature]]'' (1770) and [[David Hume]]'s ''[[Dialogues Concerning Natural Religion]]'' (1779) as well as the works of the French ''philosophers'', Priestley maintained that materialism and determinism could be reconciled with a belief in God. He criticised those whose faith was shaped by books and fashion, drawing an analogy between the scepticism of educated men and the credulity of the masses.<ref>Tapper, 320; Priestley, ''Autobiography'', 111; Schofield (2004), 37–42; Holt, 93–94, 139–42.</ref>

Maintaining that humans had no [[free will]], Priestley argued that what he called "philosophical necessity" (akin to absolute determinism) is consonant with Christianity, a position based on his understanding of the natural world. Like the rest of nature, man's mind is subject to the laws of causation, Priestley contended, but because a benevolent God created these laws, the world and the people in it will eventually be perfected. Evil is therefore only an imperfect understanding of the world.<ref>Schofield (2004), 77–91; Garrett, 55; Tapper, 319; Sheps, 138; McEvoy (1983), 50; McEvoy and McGuire, 338–40.</ref>

Although Priestley's philosophical work has been characterised as "audacious and original",<ref name=Tap314/><ref>Sheps, 138.</ref> it partakes of older philosophical traditions on the problems of free will, determinism, and materialism.<ref name="MM341">McEvoy and McGuire, 341–45.</ref> For example, the 17th-century philosopher [[Baruch Spinoza]] argued for absolute determinism and absolute materialism.<ref>Leibniz, Gottfried Wilhelm. ''Confessio Philosophi: Papers Concerning the Problem of Evil, 1671–1678''. Trans. Robert C. Sleigh, Jr. New Haven: Yale University Press (2004), xxxviii, 109. {{ISBN|978-0-300-08958-5}}. The [[s:la:Confessio philosophi|original Latin text]] and an [[s:Confessio philosophi|English translation]] of [[Gottfried Wilhelm Leibniz|Leibniz]]'s ''A Philosopher's Creed'' can be found on the Latin and English Wikisources, respectively.</ref> Like Spinoza<ref>
Stewart, Matthew. ''The Courtier and the Heretic: Leibniz, Spinoza, and the Fate of God in the Modern World''. New York: W. W. Norton (2006), 171. {{ISBN|0-393-05898-0}}.</ref> and Priestley,<ref>McEvoy and McGuire, 341.</ref>
[[Gottfried Wilhelm Leibniz|Leibniz]] argued that human will was completely determined by natural laws;<ref name="adams_1998">
Adams, Robert Merrihew. ''Leibniz: Determinist, Theist, Idealist''. New York: Oxford University Press (1998), 10–13, 1–20, 41–44. {{ISBN|0-19-508460-8}}.</ref>
unlike them, Leibniz argued for a "parallel universe" of immaterial objects (such as human souls) so arranged by God that its outcomes agree exactly with those of the material universe.<ref>
Rutherford, 213–18.</ref>
Leibniz<ref>
Rutherford, 46.</ref>
and Priestley<ref>
Schofield (2004), 78–79.</ref>
share an optimism that God has chosen the chain of events benevolently; however, Priestley believed that the events were leading to a glorious millennial conclusion,<ref name=Tap314/> whereas for Leibniz the entire chain of events was optimal in and of itself, as compared with other conceivable chains of events.<ref>
Rutherford, 12–15, 22–45, 49–54.</ref>