Posts Tagged ‘descartes’

Thus, a body is such an entity that, if one posits a longitude on it, another longitude will be found intersecting it at a right angle, and a third longitude of these two lengths will stand as a perpendicular on the point of the previous intersection. Whatever can be placed under these three magnitudes in the aforesaid manner and is also a substance is called a body … But that which is in a body, such as length, width, and depth, is known to exist not in the form of the body, but as an accident to it. For instance, one can take a piece of wax and elongate it to make it one hand longer, two fingers wider, one finger deeper. Thereafter one can modify it so that its length width and depth vary. Under such circumstances its bodily form will always persist, whereas these three dimensions do not persist. Thus, these three dimensions are accidents to the wax, while its form is another attribute. Bodies differ not with respect to form because, by belonging to one kind of category, all bodies are identical with respect to the possibility of being described by these three dimensions in the aforesaid manner.

The Metaphysica of Avicenna (ibn Sīnā), tr. Morewedge (1973), ch. 4

In a famous passage of the Second Meditation, Descartes asks us to consider a piece of wax melting on a stove. According to Descartes, as the wax undergoes this process of melting, every feature of the wax detectable by the senses changes, but the wax continues to exist. At this stage in the Meditations, we are still in doubt about whether the wax really exists. However, whether it exists or not, Descartes argues, the fact that I am capable of thinking of the wax as persisting through these changes shows that I have a concept of the wax itself which cannot be identified with anything revealed by the senses. Descartes ultimately argues that this conception of the wax itself is nothing but the concept of extended substance, i.e., of a thing which has some length, width, and breadth or other. This notion is linked to geometry, a science undertaken by the pure intellect and not by the senses.

For Descartes, this argument is a step on the way to a defence of mechanism, the thesis that bodies have no intrinsic features other than the modes of extension (ways of being extended) and interact only by collision.1

Ibn Sīnā’s discussion of the nature of body at the beginning of Metaphysica2 is, in a number of respects, interesting to set alongside Descartes. It is not so surprising that ibn Sīnā and Descartes both make the argument for distinguishing a substance from its modes/accidents by treating the substance as that which persists through a change in the accidents—presumably they both got this from Aristotle’s Categories. It is more striking that ibn Sīnā, like Descartes, uses a piece of wax as his example. It would be interesting to trace the chain of influence here. Morewedge (the translator) notes some sort of similar uses in Plato’s Theatetus and Aristotle’s Physics. To me, however, the most interesting feature of the discussion is that ibn Sīnā, like Descartes, holds that extension alone constitutes the essence/nature/form of body. Furthermore, ibn Sīnā goes on to argue that this form is identical with the body itself:

the substratum of a material form is not an actuality without a material form. It is an actual substance due to the material form. In reality, therefore, the material form is the substance … Furthermore, the material substratum is by itself not a thing without a material form. It is impossible for reason to understand the description of the substance without this necessary accident. (ch. 8)

This seems to me to mirror Descartes’s doctrine that there is only a conceptual distinction, and not a real distinction, between a substance and its principal attribute (e.g., between a body and extension).

However, despite this robust agreement on foundational issues regarding the nature of body, ibn Sīnā does not turn out to be a mechanist, and this reveals that Descartes needs an additional premise which is much less explicit in Meditations than his claims about the nature of body. Ibn Sīnā avoids drawing the mechanist conclusion because he accepts the Aristotelian doctrine of real accidents distinct from, but residing in and depending on, the substance:

If we suppose that quality, such as whiteness or blackness … stood by itself, and did not depend on anything else, and did not partake of division, then neither blackness nor whiteness could exist … A body is that which is divisible since this receptivity to division is the meaning of a body. Hence, it can be both white and black (i.e. at different times it can contain contrary characteristics).3 The peculiarity of whiteness or blackness is different from the meaning of being a body, which admits no contrary. Being black is something other than being receptive to divisibility. Whereas being receptive to divisibility is the mark of a body, blackness is nothing but blackness itself. Consequently, blackness is dependent on the body, not independent of the body. (ch. 10)

The view here is that color cannot be reduced to anything in the nature of body (i.e., extension), but nevertheless cannot exist apart from body, since only an extended thing can be colored. This is clearly an anti-mechanist color realism. This, however, does not in any way contradict the view that extension constitutes the nature of body, unless one adds the further premise that there must be an intelligible relation between the nature of a substance and its modes/accidents. This further premise (which Donald Rutherford, discussing Leibniz’s version, dubbed the Principle of Intelligibility) is indeed a core principle of Cartesian philosophy. Thus we can see that it is really Descartes’s commitment to the thoroughgoing intelligibility of nature—and in particular to the idea that all states of substances can be explicated through their natures, which can be grasped by the pure intellect—is a central plank of his argument for mechanism, and is in fact the place where at least some Medieval Aristotelians want to get off the boat.

(Cross-posted at blog.kennypearce.net)


  1. Although I won’t go into the evidence for this here, it seems to me that the overt agenda of the Meditations—securing our knowledge of the existence of God and the natural immortality of the soul—conceals a hidden agenda—selling mechanistic physics to the Catholic Church. Further, it seems to me that Descartes cares a great deal more about this hidden agenda than he does about the overt agenda. That’s not necessarily to say he’s insincere in his religious/theological assertions, but I don’t think these are among his core interests or motivations the way they are for some other early modern philosophers.
  2. I am not an expert on Medieval philosophy in general or Medieval Islamic philosophy in particular and am reading this work for the first time, in translation. Metaphysica appears to be a title given by the translator to the first (metaphysical) part of work called Dānish Nāma-i’alā’ī, a summary of Ibn Sīnā’s philosophy written in the vernacular Persian language rather than the scholarly Arabic of his other works.
  3. I think these parentheticals are the translator’s additions.

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As Elisabeth of Bohemia famously pointed out, Descartes appears to be committed to the following inconsistent triad:

  1. In every instance of causation, there is an a priori conceptual connection between cause and effect.
  2. There are no conceptual connections between mind and body.
  3. Mind and body interact causally.

The most common response to this problem among Descartes’s 17th century followers was occasionalism, the view that bodily phenomena do not genuinely cause mental phenomena but are merely reliably correlated with them, and vice versa, so that bodily phenomena may be called occasions of mental phenomena and mental phenomena may be called occasions of bodily phenomena.

The best-known advocate of this strategy (and, indeed, the best-known Cartesian after Descartes) was Nicolas Malebranche. Malebranche famously adopted full-strength occasionalism that had been popular among Medieval Islamic philosophers and theologians. On this view, there are no ‘secondary causes’ at all. God is the only true cause and created things can only serve as occasions for God to exercise God’s power. Malebranche has many arguments for this view, but one of them derives directly from the Cartesian doctrine of the a priori intelligibility of causation:

We have only two sorts of ideas, ideas of minds and ideas of bodies … since the idea we have of all bodies makes us aware that they cannot move themselves, it must be concluded that it is minds which move them. But when we examine our idea of all finite minds, we do not see any necessary connection between their will and the motion of any body whatsoever … But when one thinks about the idea of God, i.e., of an infinitely perfect and consequently all-powerful being, one knows that there is such a connection between His will and the motion of all bodies, that it is impossible to conceive that he wills a body to be moved and that this body not be moved. We must therefore say that only His will can move bodies (The Search After Truth, tr. Lennon and Olscamp, 448)

Malebranche’s view here is a much more substantive revision of Descartes than is required to escape the inconsistency above. There is a general tendency in Cartesian thought to contrast body as passive with mind as active, but Malebranche’s view appears to make created mind every bit as passive as body.

An alternative view would maintain divine occasionalism with respect to mind-body interaction, but attribute genuine activity to the mind in internal actions like imagining and willing. Indeed, Malebranche himself sometimes seems tempted by such a view, although his arguments for occasionalism appear to rule it out.

An even smaller tweak to respond to the problem of the causation of mental states by bodily states is possible, and is suggested by remarks Descartes makes in “Comments on a Certain Broadsheet”:

there is nothing in our ideas which is not innate to the mind or the faculty of thinking, with the sole exception of those circumstances which relate to experience, such as the fact that we judge that this or that idea which we now have immediately before our mind refers to a certain thing situated outside us. We make such a judgement not because these things transmit the ideas to our mind through the sense organs, but because they transmit something which, at exactly that moment, gives the mind occasion to form these ideas by means of the faculty innate to it (CSM 1:304, emphasis added).

This passage suggests, not divine occasionalism, but a sort of finite occasionalism, whereby the states of material systems give occasion for the (genuinely causal) activity of the finite mind in forming ideas of the things around it.

This hint is picked up by Arnauld and Nicole in the Port-Royal Logic:

It is thus false that all our ideas originate in the senses. On the contrary, one can say that no idea in the mind originates in the senses, although motions in the brain, which is all the senses can bring about, may provide the occasion for the soul to form various ideas that might not have been formed without this occasion (Logic, tr. Buroker, 30, emphasis added)

Here note again that it is the finite mind itself that forms the ideas and not God.

This line of response to the inconsistency with which we began makes good sense with basic Cartesian commitments, commitments which Arnauld emphasizes (against Malebranche) in On True and False Ideas. Cartesian metaphysics begins from two (alleged) clear and distinct ideas: the idea of body as extended substance and the idea of mind as thinking substance. Extension is the principal attribute of body and thought is the principal attribute of mind. Every property of a substance must be an intelligible modification of its principal attribute. A modification of an attribute is a way of possessing that attribute, i.e., a way of being extended or a way of thinking. Thus every property of a mind must be a way of thinking. But thinking is an activity, while being extended is a state. Hence every mode of mind is active and every mode of body is passive. Now from the fact that every mode of mind is active, it follows that the state of the mind in sensory perception is active, that is, when the mind perceives by means of the senses the mind acts. Insofar as the mind is in perception active and not passive, the mind’s act may be said to be occasioned by the state of the brain. (Note that this approach also would likely have seemed like the obvious one in the context due to its similarity to the Scholastic notion of the ‘agent intellect’ that ‘spiritualizes’ the material species.)

An additional reason why this looks good for Arnauld is that Arnauld is a primitivist about representation: in his view, just as it is the nature of the mind to think, so it is the nature of thought to have an object, and no account of this relation is needed. Hence for Arnauld, there is no problem about how the mind could respond to the state of the brain, since knowing about (perceiving) things like that is just what the mind does.

Arnauld does, however, have another, related problem (and concerns like this are pressed by Malebranche in various places). According to Arnauld, “our thought or perception is essentially reflective upon itself … For I do not think without knowing that I think” (On True and False Ideas, tr. Gaukroger, 71). However, we are not reflectively aware of knowing any state of the brain. It thus remains mysterious how any state of the brain could enter into the explanatory story of thought, whether as an occasional cause or a true one.

(Cross-posted at blog.kennypearce.net)

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I also find that the senses show me that the soul moves the body, but they teach me nothing (no more than do the understanding and the imagination) of the way in which it does so. For this reason, I think that there are some properties of the soul, which are unknown to us, which could perhaps overturn what your Metaphysical Meditations persuaded me of by such good reasoning: the nonextendedness of the soul. This doubt seems to be founded on the rule that you give there, in speaking of the true and the false, that all error comes to us in forming judgments about that which we do not perceive well enough. Though extension is not necessary to thought, neither is it at all repugnant to it, and so it could be suited to some other function of the soul which is no less essential to it.

Elisabeth to Descartes, 1 July 1643 (tr. Shapiro)

When Elisabeth’s correspondence with Descartes is mentioned, it is often merely to credit her with being (among) the first to raise the interaction problem for substance dualism. But this radically understates what she’s doing here, and the depth of understanding of Descartes’s system she demonstrates. The brief quotation above is one of the most decisive refutations in the history of Western philosophy. Very probably, Descartes knows it and this is why he completely changes the subject in the next letter. As Leibniz observed, “Descartes had given up the game at this point” (“New System of Nature” (1695), tr. Ariew and Garber, p. 142).

The problem is this: the fundamental starting point of Descartes’s system is the claim that by the pure intellect we grasp the essence of body (extension) and the essence of mind (thought), and we can see that these two natures have nothing in common. Further, he claims, every feature of an entity must be a modification of its essence. Thus every feature of a body must be some particular manner of being extended, and every feature of a mind must be some particular manner of thinking. Further, Descartes is committed to the a priori intelligibility of causal relations. However, since extension and thought are utterly conceptually independent no a priori causal connection between any mode of extension and any mode of thought is possible. Thus if, as Descartes claims, we know by experience that the soul moves the body (i.e., causes the body to move), then mind, body, and causation are not thoroughly intelligible as Descartes supposes. Not only does this undermine Descartes’s argument for the real distinction of mind and body; it undermines most of his philosophical system. Game over, turn the lights out, it’s time to go home.

(Cross-posted at blog.kennypearce.net)

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Interested in self-consciousness and personal identity? This week the Descartes Research Group at Western University, lead by Benjamin Hill, is holding a virtual masters seminar on Udo Thiel’s The Early Modern Subject (2011). Event details:

Friday April 29
9:00-11:00 am EDT
Western University
Arts & Humanities Building, Room 2R07

For virtual attendance, join here. The portal will open 30 minutes before the session begins.

Benjamin Hill writes:

“The session will involve Prof. Thiel answering questions and responding to critical reflections that the research group as well as a number of external experts have formulated. Philosophers interested in personal identity, consciousness, and their relationship will be especially interested in Prof Thiel’s thoughts.”

A great opportunity to dive into early modern identity questions (if you weren’t sucked into those already).

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Image from: Giovanni Aldini, Essai théorique et expérimental sur le galvanisme (Paris, 1804)

The conference program for Life and Death in Early Modern Philosophy, to be held in London on April 14–16 this year, has been announced. And it’s looking good.


Thursday 14th April 2016

The Great Hall, King’s College London, Strand, London WC2R 2LS

2.30–4.00 Tea and Registration in the Foyer of the Great Hall
4.00–4.30 Susan James, Welcome and Introduction
4.30–6.00 Michael Moriarty, The thought of death changes all our ideas and condemns our plans


Friday 15th April 2016

Birkbeck College, Clore Management Centre, Torrington Square, London WC1E 7JL

9.30–11.00 Ursula Renz, Our Consciousness of Being Alive as a Source of Knowledge
 11.15–12.45 Session 1 Session 2 Session 3
Meghan Robison

But a Movement of Limbs: On the Movement of life in Hobbes’ Leviathan

Steph Marston

Affects and Effects: Spinoza on Life

John Callanan

The Historical Context of Kant’s Opposition to Suicide

Barnaby Hutchins

Descartes’s ‘Vitalism’

Julie Klein

Life and Death in Spinoza: Power and Reconfiguration

Jonas Jervell Indregard

Kant on Beauty and the Promotion of Life

12.45–2.00 Lunch, coinciding with meeting of agreed and likely contributors to research network
2.00–3.30 Martine Pécharman, The Moral Import of Afterlife Arguments in Pascal and Locke
3.45–5.15 Session 1 Session 2 Session 3
Hannah Laurens

An Eternal Part of the Body? Spinoza on Human Existence Beyond Life and Death

Andreas Scheib

Johannes Clauberg and the Development of Anthropology after Descartes

Sarah Tropper

When the Manner of Death Disagrees with the Status of Life. The Intricate Question of Suicide in Early Modern Philosophy

Filip Buyse

Spinoza on conatus, inertia and the impossibility of self-destruction

Andrea Strazzoni

Particles, Medicaments and Method. The Medical Cartesianism of Henricius Regius

Teresa Tato Lima

Suicide and Hume’s Perspective about Human Life

5.30–7.00 Mariafranca Spallanzani, ‘Tota philosophorum vita commentatio mortis est’. Death of philosophers


Saturday 16th April 2016

Birkbeck College, Clore Management Centre, Torrington Square, London WC1E 7JL

9.30–11.00 Session 1 Session 2 Session 3
Kate Abramson

Living well, well-being and ethical normativity in Hume’s ethics

Dolores Iorizzo

Francis Bacon’s Natural and Experimental History of Life and Death (1623): A Lacuna in Accounts of the Scientific Revolution

Oliver Istvan Toth

Do we really need to die? Spinoza on the Necessity of Death in the Ethics

Giuliana di Biase

Human’s life as a “state of mediocrity” in John Locke’s Essay and in his other works

Gianni Paganini

Life, Mind and Body. Campanella and Descartes’ Connections

Piet Steenbakkers

Living Well, Dying Well: Life and Death in Spinoza’s Philosophy and Biography

11.15–12.45 Charles Wolfe, How I learned to love Vitalism
12.45–2.00 Lunch
2.00–3.30 Session 1 Session 2 Session 3
Sean Winkler

The Persistence of Identity in Spinoza’s Account of Individuals

Piero Schiavo

Controlling Death. Democritus and the myth of a death en philosophe

Matteo Favaretti

Camposampiero, The Ban of Death: Leibniz’s Scandalous Immortalism

  Mogens Laerke

The Living God. On Spinoza’s Hebrew Grammar and Cogitata Metaphysica II,6

Michael Jaworzyn

Clauberg, Geulincx, and philosophy as meditatio mortis after Descartes

Audrey Borowski,

Leibniz’s natural Mechanism. Life and Death Revisited

3.45–4.15 Meetings of learned societies
4.15–5.45 Lisa Shapiro, Learning to Live a Fully Human Life
5.45–6.00 Conclusion and Farewell

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I want to say a little bit about the way Margaret Cavendish thinks about causation.[1] A key aspect of that is an inversion, or set of inversions, of what other modern philosophers were up to. One prominent trend in modern philosophy was what is called mechanism. The central mechanist idea is that many natural phenomena are to be explained as the results of mechanical interactions. The shapes, sizes, and motions of the small parts of things explain, the mechanists argued, more than one might otherwise think. The mechanism of a clock provided a useful example: its apparently non-mechanical ability to tell the time is explained by the shapes, sizes, and motions of the parts inside. The mechanist project, so to speak, was to explain more and more of nature in this sort of way. Descartes provides an obvious example of someone taking this sort of approach. Hobbes provides an even better one, thinking that this sort of mechanical explanation applies to human cognition too.

That Hobbes and Descartes were wrong about things in this general area is one of the themes of the first part of Cavendish’s Philosophical Letters [PL].


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In preparing to talk about Descartes on machines and animals and human beings the other day, I set out looking for information about seventeenth-century automata.

One really interesting thing is Jessica Riskin’s article “Machines in the Garden” in Republics of Letters. This has a lot of information about “lifelike machines” of two sorts: religious ones – “the muttering Christs, the horn-playing angels, the eye-rolling devils, the teeth-chattering heads” – and a great variety of hydraulic machinery in the gardens of the rich and powerful.

There are also multiple online versions of Salomon de Caus’s 1615 book, Les raisons des forces mouvantes, avec diverses machines tant utiles que plaisantes, auxquelles sont adjoints plusieurs dessings de grotes & fontaines. The image below is one example of the machines illustrated, and is described as a machine “Pour faire representer le chant d’un oyseau en son naturel, par le moyen de l’eau”.

Image from de Caus, Les raisons des forces mouvantes

One online version of the book is at http://cnum.cnam.fr/SYN/FDA1.html. For another version, and more description of the book’s contents, see http://architectura.cesr.univ-tours.fr/traite/Notice/Caus1615.asp?param=en. Or alternatively, for just the illustrations, see http://gallica.bnf.fr/ark:/12148/btv1b2100042f/f1.planchecontact.

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