Stewart Duncan

This dissertation discusses the work of Thomas Hobbes, and has two main themes. The first is Hobbes's materialism, and the second is Hobbes's relationships to other philosophers, in particular his place in the mechanist movement that is said to have replaced Aristotelianism as the dominant philosophy in the seventeenth century. I argue that Hobbes does not, for most of his career, believe the general materialist view that bodies are the only substances. He believes, rather, that ideas, which are our main mechanism for thinking about the world, allow us to understand many bodies, but not to understand every thing we recognize to exist. The incomprehensible things include God---and, early in Hobbes's career, the human mind. Discussing materialism and our knowledge of God leads me to engage with the debate over Hobbes's alleged atheism. I argue that the evidence for Hobbes's atheism is weak at best. Hobbes is a sincere theist, though his view is sometimes unusual. My discussion of Hobbes's relationships to other philosophers has three parts. In chapter five I argue that Hobbes's views about method are in important ways similar to Zabarella's. In chapter six I look at Hobbes's rejection of the view, held by some scholastic Aristotelians, that accidents can sometimes exist without inhering in substances. Thus we see two sides of Hobbes's interaction with the Aristotelian tradition. Sometimes that interaction is just rejection, but at other times Hobbes takes over views from that tradition. Then in chapter seven I consider whether, and in what sense, Hobbes is a mechanist. I argue that the narrative of mechanism and Aristotelianism is a less powerful explanation than it has seemed to some to be, because it is hard to see what mechanists have in common.

Leibniz's mill argument in 'Monadology' 17 is a well-known but puzzling argument against materialism about the mind. I approach the mill argument by considering other places where Leibniz gave similar arguments, using the same example of the machinery of a mill and reaching the same anti-materialist conclusion. In a 1702 letter to Bayle, Leibniz gave a mill argument that moves from his definition of perception (as the expression of a multitude by a simple) to the anti-materialist conclusion. Soon afterwards, in the Preface to the New Essays, Leibniz gave a different mill argument. That argument depends upon there being no arbitrary and inexplicable connections in nature, because God would not create such things. Later, in the 'Monadology', Leibniz again used the mill example in arguing against materialism. That passage too, I argue, uses an argument from inexplicability rather than from Leibniz's definition of perception

Thomas Hobbes (1588-1679), whose current reputation rests largely on his political philosophy, was a thinker with wide ranging interests. In philosophy, he defended a range of materialist, nominalist, and empiricist views against Cartesian and Aristotelian alternatives. In physics, his work was influential on Leibniz, and lead him into disputes with Boyle and the experimentalists of the early Royal Society. In history, he translated Thucydides's History of the Peloponnesian War into English, and later wrote his own history of the Long Parliament. In mathematics he was less successful, and is best remembered for his repeated unsuccessful attempts to square the circle. But despite that, Hobbes was a serious and prominent participant in the intellectual life of his time.

I consider Leibniz's thoughts about Hobbes's materialism, focusing on his less-discussed later thoughts about the topic. Leibniz understood Hobbes to have argued for his materialism from his imagistic theory of ideas. Leibniz offered several criticisms of this argument and the resulting materialism itself. Several of these criticisms occur in texts in which Leibniz was engaging with the generation of British philosophers after Hobbes. Of particular interest is Leibniz's correspondence with Damaris Masham. Leibniz may have been trying to communicate with Locke, but ended up discussing Masham's version of the argument for materialism that Leibniz attributed to Hobbes.

Margaret Cavendish (1623-73) held a number of surprising philosophical views. These included a materialist panpsychism, and some views in what we might call environmental ethics. Panpsychism, though certainly not unheard of, is still often a surprising view. Views in environmental ethics - even just views that involve a measure of environmental concern - are unusual to find in early modern European philosophy. Cavendish held both of these surprising views. One might suspect that panpsychism provides some reasons for environmental concern. I argue, however, that Cavendish did not derive her environmental ethics from her panpsychism. If there is a connection, it is a developmental one, leading from the ethics to the panpsychism. The investigation of these issues also provides an occasion for thinking more generally about how Cavendish's views fit together, and whether she developed a systematic philosophy in the manner of several of her contemporaries.

Language was central to Hobbes's understanding of human beings and their mental abilities, and criticism of other philosophers' uses of language became a favorite critical tool for him. This paper connects Hobbes's theories about language to his criticisms of others' language, examining Hobbes's theories of propositions and truth, and how they relate to his claims that various sorts of proposition are absurd. It considers whether Hobbes in fact means anything more by 'absurd' than 'false'. And it pays particular attention to Hobbes's categorization of causes of absurdity and of types of incoherent proposition, arguing that Hobbes's approach is only loosely related to later discussions of category mistakes.