1/8. Leibniz on Force

Transcription

1 1/8 Leibniz on Force Last time we looked at the ways in which Leibniz provided a critical response to Descartes Principles of Philosophy and this week we are going to see two of the principal consequences of this response. One of the responses will concern the nature of Leibniz s conception of body and force and the other will concern the relationship between body and mind. The two papers we are going to be looking at both date from the 1690 s and are written within a few years of each other. The first paper, A New System of the Nature and Communication of Substances begins by referring to the way in which the medieval conception of nature was overturned by the modern system of mechanism which expelled any consideration of forms from nature and relied on deriving laws of nature from a consideration of extended mass. This latter view is clearly that of Descartes and Leibniz makes clear his initial problem with the Cartesian conception of nature when he refers to the need for a concept of force in order to understand bodies even though this concept of force is derived from metaphysics. The first reason for his departure from the Cartesian picture that is given however concerns the question of understanding what enables us to say that there is a true unity in nature. Leibniz denies that we could arrive at such a concept from matter alone and gives as his reason the point that matter is infinitely divisible and that in being so it is only a collection and not a true unity. In stating that matter is only a collection Leibniz is suggesting that a series of mathematical

2 2/8 points only happen to have come together in the order that they have and that there is nothing about the points that intrinsically requires them to hold together in the way that they do. This being so there has to be a basis for the unity of the elements of body in something other than the mathematical points that are at issue in extension. In response Leibniz points to what he calls formal atoms as the basis of the unity of bodies, atoms that have a true unity and he relates these atoms to the capacity of bodies to exercise force. The basis of force in bodies is then argued to be that there is something primitive in them that is the ground of the force they possess and which at certain points Leibniz refers to as the soul of the body. This central atomic element of the body is something that Leibniz takes to be as indivisible as the mind is generally argued to be. However not only does he take this basic element of body to be indivisible he also suggests that since it is this that has true unity that it is the substantial ground of body which shows that the essential nature of a body cannot begin or end but must subsist always. This postulation leads Leibniz to naturally next address the question of what becomes of the soul or form of the body at the death of the animal it belongs to. In response Leibniz argues that the only reasonable view is that the soul of the body and with it the machinery that constitutes the nature of its body must be conserved through all the changes of material it goes through. So in a strict metaphysical sense it follows that no body dies but rather is transformed.

3 3/8 We should be clear however that whilst we have been speaking of the soul of the body that this is something that Leibniz takes to be distinct from a rational soul or mind. The latter type of soul is what has moral qualities and these qualities are not affected by what happens to the body. What is analogous between the rational soul and the soul of the body however is that both possess a centre such that the latter has a unity similar to that expressed by the rational soul s ability to name itself I. The reason why Leibniz views the body as requiring a centre that is so closely analogous to that which is given to the personality of the mind is that without this it would follow that there was nothing substantial in body and hence that bodies were fundamentally illusory. Rather than think that bodies have material atoms that are their centre Leibniz reaches for a notion of a formal atom in order to avoid the consequence that the apparent centre of the body would still be divisible like the other parts of it. So it is an atomic substance that is being argued to provide unity to bodies or, as Leibniz also calls it, a metaphysical rather than mathematical point. This substance has in it the nature of what is living and the mathematical points of the Cartesians are only expressions of this living centre. The metaphysical point of the body is what is truly real in it and without this there would be no real unities but only collections of points arbitrarily brought together. This is the first part of Leibniz s view which establishes his departure from the Cartesian conception of body as based only on extension. Next however Leibniz turns to another difficult problem which concerns the

4 4/8 relationship between bodies and minds. In responding to this problem Leibniz argues not just with Descartes but also with the occasionalist position of Malebranche. The occasionalist position arises due to the difficulty with showing how the movement of body can be related to the mind on Leibniz s view although in fact this view is really based on a general difficulty with causal interaction of any kind. Prior to outlining Leibniz s departure from the occasionalist position it should first be pointed out that he agrees with the occasionalists that there is no real influence of one created substance on another. However rather than take the consequence of this lack of interaction between substances to be that God must be at work in the laws that govern the operation of the substances Leibniz adopts a different view. What Leibniz argues is that the creation of substances provides two qualities to them: firstly, their ability to produce everything from themselves spontaneously and secondly that the substances all are acting in conformity with each other. The suggestion is that the mind perceives things not from the effect on it of the body but rather through its own constitution and that this constitution is so governed that what the mind perceives accords with what the body it is related to is contiguous with. The rational soul operates as if there were only itself and God in the world as it is not affected by the body but it operates in complete agreement with the body and this complete agreement which is regulated by God at the origin of the mind s existence is what is the basis of the apparent unity of mind and body. From this

5 5/8 hypothesis it follows that whilst we appear to be determined in our choices that this is in fact only an appearance as nothing that emerges from body can have any effect upon it. Each mind is, as he puts it, a world apart and sufficient unto itself and this isolation of the substance of the mind enables it to always be understood in a moral way. Leibniz s acceptance of the claim that substances do not truly interact always requires him however to view material substances as governed all by their own internal laws and not by their relations with other bodies. The relationship of mind and body is also explained in terms of two clocks set simultaneously by God at their origin. Shortly after publishing The New System of Nature Leibniz published Nature Itself and the latter work is more directly aimed at responding to occasionalism. The two questions which this later work is concerned with are stated early as being to show what the nature of things consists in and whether there is any power of action in created things. In response to the first question Leibniz denies that there is a world-soul or principle animating the whole of nature but also again rejects equally the mechanistic view. In this piece Leibniz argues that the foundation of the laws of nature is not found in the Cartesian principle of the conservation of the quantity of motion stating instead that the correct principle would assert that there is always the same quantity of active power in the world. Rather than go on to focus directly on this contrast between motion and force however Leibniz first responds to the basic hypothesis of

6 6/8 occasionalism that laws of nature are grounded on divine laws. In response to this claim Leibniz asks whether what is meant by it is that the divine law is related to the things it governs intrinsically or extrinsically. If the divine law is extrinsic to the things it acts upon then it follows that there is no internal principle of these things at all. On this view God s will is operative initially but then despite having no effect on the internal operation of the things they continue to be governed by his will and this Leibniz claims is to turn all of nature into a perpetual miracle. The only alternative to this is to say that the extrinsic operation of the divine law is one that requires perpetual renewal which however ensures that God must constantly be acting just for anything to be at all. It seems then preferable to view the occasionalist claim as being that God s will is not merely extrinsic to the things it operates on but intrinsic to their mode of operation. For this to be the case however it follows that there must be something internal to the things that is capable of being operated upon or, to put this otherwise, that they have themselves a nature. Unless they do have a nature of their own it also follows that the occasionalist position collapses into Spinozism. This leads naturally to the second question of whether created substances act. Now we have just reached the point that these substances require a nature of their own and surely part of such a nature is to act and suffer. This is the thesis adopted by Leibniz that basically for something to be a substance is for it to be capable of acting although he in fact even goes further than this and claims that substances never cease acting. If we take

7 7/8 the substances to act however then we are no longer presenting any form of occasionalism as occasionalism is founded on the denial that material substances can act and who likewise seem unable to provide any account even for the actions of minds. On this basis Leibniz denies that freedom can be preserved as a property of ours on the occasionalist view. If we look at bodies then the basic claim is that bodies are inert in the sense that once moving they do not naturally come to rest and once resting do not of themselves come to move. On the grounds of geometrical or mathematical properties Leibniz has no basis to dispute this characterization of bodies and indeed he refers to the primary matter of bodies as involving this property of inertia. However to this Leibniz adds the claim that bodies contain a primitive motive force which he also terms the conatus of bodies. It is this which he, in The New System, he termed the soul of the body or the basis of its true unity. In explanation of this claim Leibniz speaks of two ways of discussing matter, in terms of secondary or primary considerations. Primary matter is what he has termed passive but to this there corresponds no soul whereas secondary matter does include soul and is no longer completely passive. A ground for claiming that bodies contain this element of soul or force is subsequently presented by Leibniz when he speaks of what is occurring when a body is in motion. When a body is in motion it is not, he states, merely in a given place but also possessed of a tendency to change its place and this tendency is what ensures that its future state will grow out of

8 8/8 its present one. This tendency within the body is what differentiates the body that is moving from the one that is at rest. The point about this tendency is that it also explains why it is that different bodies are distinguishable from each other as each body has distinct tendencies from each other one in terms of their intrinsic qualities and not merely by reference to extrinsic denominations. Hence bodies are intrinsically different to each other on the grounds of their distinct internal tendencies. This even leads Leibniz to his striking claim that there is no perfect similarity in nature or, in other terms, that nature is a regulated system of differences. So the consequence of recognition of the claim that bodies have their own natures is that each body is an individual, that is, intrinsically distinct from every other. Force is what makes each body move and this force is internal to the bodies in question to such a degree that once they have begun to move it is unclear how they could come to stop.