Cartesian Ontology and First Philosophy

Modern PhilosophyIn my PHIL 202: Modern Philosophy course, we just finished a segment looking at Descartes in Context. We read Don Rutherford’s “Innovation and orthodoxy in modern philosophy”1, and some texts from Montaigne, Bacon, and Galileo, which are included in Ariew & Watkins’ Modern Philosophy anthology2, before working through the Meditations, selected Objections and Replies, Book I of Spinoiza’s Ethics and Leibniz’s Monadology. Our focus involved taking general aspects of Aquinas’ synthesis of Aristotelian Natural Philosophy and Catholic Theology as the background against which early modern thinkers propose a variety of alternative approaches to understanding the natural world (both in itself and in whatever relations it might have to something that is not identical with it) . We looked at skeptical considerations as a way of highlighting relevant differences between custom, on the one hand, and both faith and reason, on the other, and used the contrasts between existing ‘orthodoxies’ and modern ‘innovations’ in order to appreciate the argumentative contexts into which treatises on method, particular applications of new methods, and systematic works on first philosophy are introduced.

The primary focus when we read Descartes, Spinoza and Leibniz was their respective ontologies. The Cartesian view of substance as ‘what exists in itself and can be conceived through itself’, of attributes as ‘what the intellect perceives of a substance as constituting its essence’, and of modes as ‘particular determinate expressions of the attributes of substance’ was the unifying theme for understanding the philosophically significant diversity in the views that we often refer to as Cartesian Dualism, Spinoza’s Monism, and Leibnizean Idealism. We addressed differences between the analytic method by which we discover first principles and the synthetic method by which we make reference to these principles in arguments aimed to demonstrate the necessity of some claim. We talked about Descartes’ view that he had, in fact, followed the ‘geometrical method’ in the text of the Meditations, and about the differences between that text and his synthetically arranged recap of its arguments in the Replies, as a way of orienting ourselves to the (otherwise somewhat strange) method we see Spinoza following in the Ethics. We also talked about the ontologically and theologically puzzling notion of a causa sui, again, as a way of orienting ourselves to the (otherwise somewhat strange) method we see Spinoza following in the Ethics.

The resulting view of Nature, and of human being’s orientation to it, was seen as providing a significant contrast to more orthodox theological positions that appear to be just as central to Cartesian and Leibnizean syntheses of natural philosophy and metaphysics as they are to the Scholastics. We then looked at Leibniz’s Monadology (regrettably briefly) for its analytic approach of proceeding from our perceptions of bodies to an intellectual grasp of the first principles that ground the extension we attribute to them–and its resulting challenge to both Descartes and Spinoza in their treatment of extension as a primary attribute of substance–and for the view of the realms of nature and of grace that it develops as providing a potentially viable option to the necessitarianism and naturalism of Spinoza. All in all, it was a brief run through some of the central issues and challenges of early modern philosophy that became orientational for my own thinking about this period and my own research on it through graduate training that stressed historically and contextually informed reconstructions of the philosophical positions and arguments of figures from our past.

It wasn’t unitl after the mid-term exam that I came clean with my students about what I had been doing; namely, intentionally avoiding the historical narrative by reference to which so many students have been, and continue to be, oriented to the early modern period. If Descartes as foundationalist epistemologist leaves us inside our own minds–unable to get out except through the most transparent of transparently bad arguments–and then Descartes as philosopher of mind has such an untenable view of the mind and of the mind-body relationship, then I am not so sure we are doing ourselves or our students any favors by devoting precious time that could be spent doing philosophy to considering his views. Rather than excising (or exorcising) his thought from our courses on the basis of these facts, however, we can just as well treat the egregiousness of the errors we attribute to him as epistemologist and as philosopher of mind, in the contemporary senses of those words, to be good reasons for being suspect about the principles of interpretation that would lead us to treat his thought in these ways in the first place. If other approaches allow us to interpret ‘what he is up to’ in ways that are more consistent with conventional views concerning his greatness as a thinker and an innovator, and that make it more challenging (rather than less) to claim philosophical superiority for ourselves, we might be led to prefer such approaches. This might be especially so, if we are concerned to challenge ourselves and our students to work through these discourses carefully and respectfully, and to avoid the temptation simply to fall back on what we are pretty sure we already know in the context of activities designed to help us reflect on both the enabling and disabling effects of our own sense of security.

So, now, in an effort also to inform my students about other ways of orienting ourselves to the thought of modern figures, and to motivate a transition to Hume and Kant, I find myself introducing the ‘Great Divide’ between Rationalism and Empiricism. This means that I need to articulate the advantages I see to the approach to early modern thinkers that I have taken with them over an approach that prioritizes a much neater divide into opposing camps, and a narrative of progressively greater consistency with fundamental principles of the movement, which carries it out to logical consequences that motivate eventual abandonment, etc.3 So far, I have introduced the idea that that epistemological approach is a conventional one that, whatever it has going for it, can (and for a philosophically minded historian likely should) be brought into question. I have also suggested that we might compare its ongoing acceptance to the acceptance of a self-proclaimed victor’s account of a battle, and that we might need to do some work to see for ourselves what a neutral third party might identify as the real tensions leading the parties to align themselves in the ways they did. If, thorugh the process, we return to the view we started with, we will at least have gained more insight into that view and made it our own. If not, then, we will have learned something about that view, and maybe about ourselves in relation to it, that makes it no longer seem as attractive to us as it once did.

Whether these suggestions lead to fruitful discussion of post-Newtonian and post-Lockean moderns, like Hume and Kant, for whom there is a modern empiricism to contrast with modern rationalism, as well as a number of different views concerning general ontology and causality (in themselves and in relation to the natural and human sciences) remains to be seen. What I can highlight right now, on the basis of the ontological approach we have been taking, are the following philosophically relevant differences between the rationalists, and the suggestion that these differences are more central to their philosophical work–in terms of its aims, methods, and outcomes–than is the common commitment concerning the human intellectual capacity for knowledge that qualifies each as a rationalist.

Substance: Pluralism (Descartes, Leibniz) vs. Monism (Spinoza)

Attributes of Substance: Is extension a primary attribute of substance? Yes (Descartes, Spinoza) vs. No (Leibniz)

Starting with views about substance and attributes, we see that the three thinkers divide themselves up differently, with one agreeing with Descartes in each case and the other disagreeing in each case. Spinoza rejects the view that there is (or can be) more than one substance–absolutely and as concerns the sharing of an attribute, but he agrees with Descartes that extension is a principle attribute of substance. Leibniz agrees that there is (and can be) more than one substance–absolutely and as concerns the sharing of an attribute (i.e., for Leibniz, too, there is more than one thinking substance or mind), but he disagrees with both that extension is a primary attribute of substance. Accordingly, despite their agreement that the human mind has a distinctly intellectual capacity, and that its representations vary in terms of their clarity and distinctness, they end up with importantly different views concerning God and nature, the metaphysical foundations of physics and other natural sciences, and human nature.

Finite Substances and Modes: Union vs. Identity, Causality, and Human Nature

Descartes: particular finite minds (thinking substances) are contingently united with particular bodies (modes of extended substance) in a substantial union that we call a human being. The union enables (or grounds) a particular causal relationship between the states and changes of state in the one and those in the other (so the states of the mind can cause motions in the body, and the states of the body can cause ideas in the mind). This ends up being more like the Aristotelian view of human beings as rational animals than is often noticed—the rational soul serves as the substantial form of the human body (the human body is not a substance, but the human being is). Descartes thinks we can get away from animal souls and vegetative souls, both as ‘parts’ of the human soul, and as first principles of capacities to be in determinate states and to undergo changes of state in animals and plants (mechanistic physiology can, allegedly, take over in these areas). The role of the intellect, or rational soul, as form in relation to the modes of extension of the body in the life of the human being, however, is not what defines what the soul is—the soul is substantial (exists in itself and can be conceived through itself), its primary attribute is thinking, and it can also exist as a purely thinking thing independently of any particular relationship to bodies. This is Cartesian Dualism as it relates to human nature, as I understand it. There are certainly questions and challenges, but there are also provisional responses and similar challenges for other views in philosophical anthropology.

Spinoza: particular finite modes of thinking (attribute of the one substance) = particular finite modes of extension (parallel attribute of the one substance) = the mind/body of the human being. The human mind is the idea of the human body (the human being’s reality qua determinate mode of thinking): the human body is the object of that same idea (the human being’s reality qua determinate mode of extension. They are identical in themselves, so there is no real distinction and no contingent union. Neither is a substance; each is merely modally distinct from the substance of whose attribute it is a mode (same substance, just a difference in degree of ( perfection/power). The ‘relation’ between these ’two’ modes is not a contingent, yet lawful, causal unity but an absolutely necessary relation of identity. This view doesn’t seem to arise as a response to problems for Cartesian mind-body dualism, on the basis of a more consistent rationalism. Instead, it appears to follow from a particular conception of God as causa sui, and the pure ontology of perfection and limitation that follows from that.

Leibniz: particular finite minds (intellectually acute monads) are contingently related to particular collections of other finite substances (slumbering monads) in such a way that they together consitute a substantial union that we call a human being. The union is not one between distinct kinds of substance, and it is not one that presupposes or grounds genuinely causal relationships between distinct substances. The contingent, yet lawful, connection between the mind and the body is one that is grounded in the natures of each of the finites substances involved. These natures, in turn, are themselves grounded in God’s infinite intellect. The lawful connection between mental phenomena and physical phenomena is not, in principle, any different or less intelligible than the lawful connection between one physical phenomenon and another–each of these connections between phenomena arises as it does through the spontaneous activity of the substances that ground them and in accordance with a harmony that has been pre-established between all of these activites and effects in each and every case for created substances. The view contains a response to problems of Cartesian mind-body dualism, but it is one that appears be based on ontological considerations concerning substances and the attributes through which alone the intellect can think something through itself as existing in itself.


  1. Donald Rutherford, ed. The Cambridge Companion to Early Modern Philosophy. Cambridge: Cambridge University Press, 2006. 

  2. Ariew, Roger, and Eric Watkins. Modern Philosophy: An Anthology of Primary Sources. Indianapolis, Ind: Hackett Pub. Co, 2009. 

  3. I borrow some of my framing here from Loeb, Louis E. From Descartes to Hume: Continental Metaphysics and the Development of Modern Philosophy. Ithaca, N.Y: Cornell University Press, 1981. 

Leave a Reply

Your email address will not be published.