Joseph Priestley was a man of many and varied intellectual interests. This thesis surveys his philosophical thought, with a central focus on his philosophical theology. The subject can be divided into two parts, natural theology and moral theology. Priestley's natural theology is a perhaps unique attempt to combine and harmonize materialism, determinism and theism, under the auspices of Newtonian methodology. His materialism is based on three arguments: that interaction between matter and spirit is impossible; that a dynamic theory of matter (...) breaks down the active/passive dichotomy assumed by many dualists; and that Newton's "Rules of Reasoning in Philosophy" require the rejection of the "hypothesis" of the soul. His determinism arises from his theory of causation. He attempts to show that the only acceptable account of causation is one in which every cause is invariably followed by the same effect, and that libertarianism violates this central assumption of scientific thought. His theism rests on the Argument from Design. He defends the Argument by trying to show that none of the alternatives to Design advanced in Hume's Dialogues concerning Natural Religion constitute a plausible scientific hypothesis. His critics accused his synthesis of materialism, determinism and theism of leading to atheism or pantheism. His defence against these charges is that his system is essentially theistic, and that its ontology is determined by the Argument from Design. Priestley's moral theology is also in part a response to Hume's Dialogues. He offers a number of replies to the "problem of evil". Evil and adversity heighten our appreciation of good; they are a consequence of the finitude of the creation; they follow from the desirability of having a world governed by general laws; and they make possible the achievement of moral character. Character-formation is his main defence, and his methodology requires him to show that adversity leads more often than not to positive results. This requirement is embodied in his progressivist philosophy of history. History, he holds, exhibits temporal purpose and Design, just as nature exhibits atemporal purpose and Design. Priestley's political thought can be seen as arising from his moral theology, mediated by the notions of "luxury", which he regards as morally harmless, and "idleness", which is the main source of moral evil. His combination of liberalism and radicalism is examined both for internal consistency and as a response to the events of his day, ending with the French Revolution. Priestley is interesting partly for his unorthodoxy, partly for the inter-connectedness of his diverse concerns, and partly because he debated with distinguished contemporaries. Throughout the thesis his views are juxtaposed with those of Hume, Reid, Price, Boscovich, Burke and a number of other thinkers. (shrink)

Empiricism is a claim about the contents of the mind: its classic slogan is nihil est in intellectu quod non fuerit in sensu, ‘there is nothing in the mind (intellect, understanding) which is not first in the senses’. As such, it is not a claim about the fundamental nature of the world as material. I focus here on in an instance of what one might term the materialist appropriation of empiricism. One major component in the transition from a purely epistemological (...) claim about the mind and its contents, to an ontological claim about the nature of the world, is the new focus on brain-mind relations in the eighteenth century. Here I examine a Lockean trajectory as exemplified in Joseph Priestley’s 1777 Disquisitions Relating to Matter and Spirit. But Locke explicitly ruled out that his inquiry into the logic of ideas amounted to a ‘physical consideration of the mind’. What does it mean, then, for Priestley to present himself as continuing a Lockean tradition, while presenting mental processes as tightly identified with ‘an organical structure such as that of the brain’ (although he was not making a strict identity claim as we might understand it, post-Smart and Armstrong)? One issue here is that of Priestley's source of ‘empirical data’ regarding the correlation and indeed identification of mental and cerebral processes. David Hartley’s theory in his 1749 Observations on Man was, as is well known, republished in abridged form by Priestley, but he discards Hartley's 'vibratory neurophysiology' while retaining the associationist framework, although not because he disagreed with the former. Yet Hartley was at the very least, strongly agnostic about metaphysical issues (and it is difficult to study these authors while bracketing off religious considerations). One could see Locke and Hartley as articulating programs for the study of the mind which were more or less naturalistic (more strongly so in Hartley’s case) while avoiding ‘materialism’ per se; in contrast, Priestley bit the (materialist) bullet. In this paper I examine Priestley’s appropriation and reconstruction of this ‘micro-tradition’, while emphasizing its problems. (shrink)

Reid said little in his published writings about his contemporary Joseph Priestley, but his unpublished work is largely devoted to the latter. Much of Priestley's philosophical thought- his materialism, his determinism, his Lockean scientific realism- was as antithetical to Reid's as was Hume's philosophy in a very different way. Neither Reid nor Priestley formulated a full response to the other. Priestley's response to Reid came very early in his career, and is marked by haste and immaturity. In his last decade (...) Reid worried much about Priestley's materialism, but that concern never reached publication. I document Reid's unpublished response to Priestley, and also view Reid's response from Priestley's perspective, as deduced from his published works. Both thinkers attempted to base their arguments on Newtonian method. Reid's position is the more puzzling of the two, since he nowhere makes clear how Newtonian method favours mind-body dualism over materialism, which is the central debate between them. (shrink)

The paper focuses on Priestley’s complex views on the essence of God in connection with his materialism, elaborated in the Disquisitions Relating to Matter and Spirit (1777/ 1782). This issue is crucial if one wishes to get a clear idea of what Priestley’s materialism amounts to; whether it is mainly a thesis about the material grounds of the human mind (“psychological materialism”), or a more far-reaching one about what kind of substances exist in the world (a version of “ontological materialism”). (...) The claim that God may be material allows for the most radical version of ontological materialism according to which everything in the world is material, without altogether denying that God exists. In fact, Priestley considers and partially defends at least three different views on the potential materiality of God: (1) an agnostic stance that is his official view, (2) materialism about God based on his own theory of matter, and (3) “gross” materialism about God. The aim of the paper is to analyze these three views, in particular concerning what kind of materialism they support and whether they can contribute to the consistent Christian materialism Priestley envisaged. (shrink)

Reid said little in his published writings about his contemporary Joseph Priestley, but his unpublished work is largely devoted to the latter. Much of Priestley's philosophical thought- his materialism, his determinism, his Lockean scientific realism- was as antithetical to Reid's as was Hume's philosophy in a very different way. Neither Reid nor Priestley formulated a full response to the other. Priestley's response to Reid came very early in his career, and is marked by haste and immaturity. In his last decade (...) Reid worried much about Priestley's materialism, but that concern never reached publication. I document Reid's unpublished response to Priestley, and also view Reid's response from Priestley's perspective, as deduced from his published works. Both thinkers attempted to base their arguments on Newtonian method. Reid's position is the more puzzling of the two, since he nowhere makes clear how Newtonian method favours mind-body dualism over materialism, which is the central debate between them. (shrink)