Online research in philosophy

It is widely-accepted that Descartes is a substance dualist, i.e. that he holds that there are two and only two kinds of finite substance – mind and body. However, several scholars have argued that Descartes is a substance trialist, where the third kind of substance he admits is the substantial union of a mind and a body, the human being. In this paper, I argue against the trialist interpretation of Descartes. First, I show that the strongest evidence for trialism, based on Descartes' discussion of so-called incomplete substances, is highly inconclusive. Second, I show that a kind of unity (‘unity of nature’), which is had by all and only substances, is not had by human beings. The fact that the proper parts of a human being, namely a mind and a body, are of different natures entails that what they compose has at most a ‘unity of composition’. And a thing cannot be a substance in virtue of having a unity of composition. Therefore, Cartesian human beings are not substances.

Property dualism is enjoying a slight resurgence in popularity, these days; substance dualism, not so much. But it is not as easy as one might think to be a property dualist and a substance materialist. The reasons for being a property dualist support the idea that some phenomenal properties (or qualia) are as fundamental as the most basic physical properties; but what material objects could be the bearers of the qualia? If even some qualia require an adverbial construal (if they are modifications of the thing that is conscious because of them, not properties of something else to which the subject of consciousness is related), then the property dualist can be driven to speculative forms of materialism none of which, at this point, looks more likely to be true than the more modest versions of emergent dualism defended by contemporary substance dualists.

This paper pushes to the claim that the following is Descartes’s fundamental thesis: something has self-presenting states and self-presenting states only. Were he to have established this he would have revamped our worldview in essentially the manner he wished to revamp it. From this proposition one can get an argument for the substance view of the mind in Descartes’s writings.

Traditionally, independence accounts of substance have held pride of place. Aristotle, Aquinas, Descartes and Spinoza—among many others—accepted independence accounts in one form or another. The general thrust of such views is that substances are those things that are apt to exist in themselves. In this paper, I argue that several contemporary independence theories of substance—including those of Kit Fine, E.J. Lowe and Michael Gorman—include an ad hoc element that renders them unacceptable. I’ll also consider the theories of Hoffman and Rosenkrantz.

Substance: Its Nature and Existence investigates the very nature and existence of individual substances, including both living things and inanimate objects. It provides an accessible introduction to the history and contemporary debates of this important and often complex issue. Starting with a critical survey of the main historical attempts by Aristotle, Descartes, Spinoza, Locke and Hume to provide an analysis of substance, the authors present the view that a substance must satisfy an independence condition which could not be satisfied by an insubstantial entity. Throughout the book, the authors also consider problems for the notion of substance raised by the unity of the parts of organisms and explore the problem of how we can actually know what kinds of physical substance there are.

I attempt to rebut Dean Zimmerman's novel argument (2010), which he presents in support of substance dualism, for the conclusion that, in spite of its popularity, the combination of property dualism with substance materialism represents a precarious position in the philosophy of mind. I take issue with Zimmerman's contention that the vagueness of ‘garden variety’ material objects such as brains or bodies makes them unsuitable candidates for the possession of phenomenal properties. I also argue that the ‘speculative materialism’ that is available to a substance materialist property dualist who abandons the identification of persons with such garden variety objects is significantly more attractive than Zimmerman allows. Although I do not attempt to refute its substance dualist rival, I conclude that the combination of property dualism with substance materialism can withstand Zimmerman's objections.

It can be shown that, if we assume 'substance dualism', or the real distinctness of the soul from the body, then the standard objections to the Cyclical Argument in the "Phaedo" fail. So charity would presumably require that we take substance dualism to be presupposed by that argument. To do so would not beg any question, since substance dualism is a significantly weaker thesis than the immortality of the soul. Moreover, there is good textual evidence in favor of this presumption. A closer look at the immediately preceding passage, viz. "Socrates' Defense", reveals an argument for a real distinction between soul and body, not unlike Descartes' famous argument, based on the identification of an activity in which the soul can in principle engage on its own, without assistance from the body. The argumentative project of the "Phaedo," on this reading, becomes: given that the soul is really distinct, show that it is immortal. And Plato aims to do this in two stages. The three initial arguments are meant to establish merely the minimal claim that the continued existence of the soul across cycles of reincarnation is the most plausible view to take, given substance dualism; and it is left to the Final Argument to argue for something that we might regard as immortality, that is, the imperishability of the soul, come what may.

It can be shown that, if we assume 'substance dualism', or the real distinctness of the soul from the body, then the standard objections to the Cyclical Argument in the "Phaedo" fail. So charity would presumably require that we take substance dualism to be presupposed by that argument. To do so would not beg any question, since substance dualism is a significantly weaker thesis than the immortality of the soul. Moreover, there is good textual evidence in favor of this presumption. A closer look at the immediately preceding passage, viz. "Socrates' Defense", reveals an argument for a real distinction between soul and body, not unlike Descartes' famous argument, based on the identification of an activity in which the soul can in principle engage on its own, without assistance from the body. The argumentative project of the "Phaedo," on this reading, becomes: given that the soul is really distinct, show that it is immortal. And Plato aims to do this in two stages. The three initial arguments are meant to establish merely the minimal claim that the continued existence of the soul across cycles of reincarnation is the most plausible view to take, given substance dualism; and it is left to the Final Argument to argue for something that we might regard as immortality, that is, the imperishability of the soul, come what may.

Locke’s argument for the primary-secondary quality distinction is compared with Descartes’s argument (in the Principles of Philosophy) for the distinction between mechanical modifications and sensible qualities. I argue that following Descartes, Locke’s argument for the primary-secondary quality distinction is an essentially a priori argument, based on our conception of substance, and the constraints on intelligible bodily interaction that this conception of substance sets.

Descartes claims that God is a substance, and that mind and body are two different and separable substances. This paper provides some background that renders these claims intelligible. For Descartes, that something is real means it can exist in separation, and something is a substance if it does not depend on other substances for its existence. Further, separable objects are correlates of distinct ideas, for an idea is distinct (in an objective sense) if its object may be easily and clearly separated from everything that is not its object. It follows that if our idea of God is our most distinct idea, as Descartes claims, then God must be a substance in the Cartesian sense of the term. Also, if we can have an idea of a thinking subject which does not in any sense refer to bodily things, and if bodily things are substances, then mind and body must be two different substances.