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How are souls related to bodies? A study of John Buridan.

MEDIEVAL PHILOSOPHERS HAD NO SINGLE RESPONSE to the difficult question of how souls are related to the bodies they animate. In this respect, the theory of psychological inherence advanced by the noted Parisian philosoppher John Buridan is a case in point. Buridan offers different accounts of the soul-body relation, depending upon which of two main varieties of natural, animate substance he is explaining. In the case of human beings, he defends a version of immanent dualism: the thesis that the soul is an immaterial, everlasting, and created (as opposed to naturally generated) entity, actually inhering in each and every body it animates, and thus numerically many.(1) But when his explanandum is the relation between nonhuman animal or plant souls and their bodies, Buridan is a materialist; that is, he regards the sensitive and vegetative souls of such creatures as no more than collections of material, extended powers exhaustively defined by their biological functions, and hence as corruptible as the particular arrangements of matter they happen to animate.

In the larger context of medieval Aristotelianism, the fact that Buridan has a hybrid approach to the question of psychological inherence is neither remarkable nor especially interesting. Obviously, some combination of materialism and dualism seems called for if the soul-body relation is to be explained in a way that is both naturalistic and consistent with the possibility of personal immortality for some class(es) of corporeal, animate things. What is both remarkable and interesting, however, is the way in which Buridan manages the details of his hybrid account, that is, the particular explanations he gives under its materialistic and dualistic aspects.

My aim in this paper is to examine Buridan's answer to the very basic question of what it means for the soul to inhere in the body. This question is discussed at several junctures in the third and final version of his Questions on Aristotle's De anima (hereafter "QDA"),(2) though as we shall see below, his explanation of how nonhuman souls inhere in their bodies is of a piece with the more general theory of inherence presented in his other writings.


Nonhuman Souls. The question of how the soul inheres in the body is first addressed as such in QDA 2.7. Like virtually all of the questions in this work, QDA 2.7 is based on a lemma from Aristotle's De anima: in this instance, the observation in De anima 2.2 that it is possible for some plants and animals to survive physical division, from which we are to conclude that before division, their souls are actually one but potentially many.(3) For Buridan, this claim raises the question of how we are to understand the presence of the soul's nutritive and sensitive powers in corporeal bodies: in what sense does the whole soul of an organism inhere in its body if a single division of the quantitative parts of that body gives rise to two new whole souls? Since QDA 2, like De anima 2, addresses the nature and function of the sensitive part of the soul, Buridan gives his answer in the context of the psychology of brute or nonhuman animals, creatures whose souls are paradigmatically sensitive.

In the main part of QDA 2.7, Buridan introduces four metaphysical principles which he takes to govern the inherence of nonhuman animal souls, and thus also to explain how the sensitive and vegetative souls of such creatures can be in each part of their bodies. I shall discuss each of these principles in turn, and then examine Buridan's dualistic account of the relation between human souls and their bodies in QDA 3.

A. The Extensionality Principle. The first principle governing the inherence of nonhuman souls in their bodies is attributed to Aristotle and defined as follows: "The vegetative soul, sensitive soul, and so forth in a horse are not distinct in different parts of the body, but the vegetative, sensitive, and appetitive [souls] are extended throughout the whole body of the animal [per totum corpus animalis extensa est]" (QDA 2.7, p. 89). The vegetative and sensitive souls of brute animals, together with their characteristic powers of nutrition, growth, and desire (sometimes called "souls" in their own right, as in "nutritive soul," "appetitive soul," and so on), are said to be "extended throughout the whole body" because they are derived from its matter. The extensionality principle contends that when an animating power has been derived from an extended subject, it must commensurably inhere in that subject.

Buridan elsewhere draws a distinction between two different modes of inherence which helps to clarify how one thing can be said to inhere commensurably in another. A power or capacity, he says, inheres in a subject (1) as a proximate potentiality (potentia propinqua), just in case it can act or be acted upon immediately, without the assistance of a mediating quality disposing it to act or be acted upon; or (2) as a remote potentiality (potentia remota), just in case it can only act or be acted upon with the assistance of a mediating quality so disposing it. In this way, some powers of the soul are said to be proximate, others remote:

Although the soul can exercise some of its operations immediately, it cannot [so exercise] all of them. For example, if we suppose that there is only one substantial form in a human being, namely, the intellective soul, a human body would be informed by each. Nevertheless, it [the intellective soul] has been so abstracted that it is not derived from a subjective potentiality, nor extended by its extension, which is also why it does not need to use a corporeal organ for its principal operations, that is, willing and understanding. And yet it does need a corporeal organ, and certain qualitative dispositions of a [corporeal] organ, to exercise its other operations, for it needs an eye to see, an ear to hear, and so forth.(4)

Thus, the intellective soul is proximately potential to its definitive or essential operations of willing and understanding, since it is possible for intellectual creatures to engage in those activities without needing any specific arrangement of matter in the form of an organ.(5) But the powers characteristic of the vegetative or sensitive souls--such as nutrition, growth, sensation, and desire--are, considered by themselves, only remote potentialities. They become proximate potentialities only when considered together with their determining qualitative dispositions. Thus, we say that the sensitive power together with the eye, an arrangement of matter disposed to register light and color, is immediately capable of seeing; the sensitive power together with the ear, an arrangement of matter disposed to register vibrations in the air, is immediately capable of hearing, and so on.

The distinction between proximate and remote potentialities is important for understanding the precise sense in which Buridan understands the powers of the vegetative or sensitive soul to be extended throughout the body. The extensionality principle is false if those powers are conceived as proximate potentialities, since the sensitive soul is proximately x-ing not throughout the whole body but only locally, that is, where it inheres in physical organs disposed to x-ing. Thus, it is proximately seeing only in the eye, proximately hearing only in the ear, and so on. But the principle is true if those powers are conceived as remote potentialities, since each and every part of the body of a plant or animal is potentially x-ing but for the mediating qualitative disposition required for x-ing. Buridan explains his understanding of this distinction in response to what looks to have been a student query:

But it is reasonable for you to ask whether in the foot of a horse, the soul is capable of seeing. And I say that it is, speaking of a principal and remote potentiality, since taken by itself it is naturally suited to see, and it would see in the foot if God and nature were to form an eye in the foot for it. But it is not in the foot as a proximate potentiality for seeing, because by "proximate potentiality" we must understand either the required dispositions together with the principal agent, or the principal potentiality itself in possession of the dispositions it needs to operate. And when it is without them, it is called a "remote potentiality." Nor is that [remote] potentiality [posited] pointlessly in the foot, since it exercises other operations [besides seeing] there. (QDA 2.5, pp. 66-7)

So even if the sensitive soul's powers are manifested only locally, there remains a sense in which they are present throughout the whole body:

If an eye were in the foot in the same way that it is in the head, [that is,] as far as qualitative dispositions are concerned, we would undoubtedly see with an eye belonging to the foot just as we do with an eye belonging to the head. For the substance of the soul, which is naturally suited to exercise its every operation where the organic dispositions required for this have been present, is everywhere throughout the whole body. (QNE 6.3.119ra; cf. QDA 2.19, pp. 326-7)

Buridan's extensionality principle as applied to the soul, then, is a claim about capacities of the soul conceived as remote potentialities.

B. The Subject Identity Principle. The second principle advanced by Buridan states that in nonhuman animals, "the sensitive soul is not separate in subject from the vegetative soul," but part of the same identical subject of which the vegetative soul is also a part (QDA 2.7, p. 91). In defense of this principle, Buridan notes only that it raises the question of whether there is a plurality of souls in any living thing; he claims to have answered this question in the negative in a previous discussion. This is a reference to QDA 2.4, where Buridan presents five arguments against the view that the same animal is possessed of vegetative and sensitive souls distinct not only in definition, but also in reality. The first three of these arguments are aimed at reducing the pluralist position to absurdity. If the vegetative and sensitive souls are really distinct, Buridan argues, then:

(1) In a horse, God could separate one soul from the other, making the horse into either an animal or a plant. But then the horse would be composed of both animal and plant, which is absurd. (2) The vegetative soul of a horse would be more noble than its sensitive soul, since the former acts on a substance through nutrition and generation, whereas the latter is merely the passive recipient of external sensible species. But this is absurd.(6)

(3) Since the sensitive souls of a dog and a horse would have the same substantial nature, they must differ in some specific, substantial form added to them. Proof: This added form will be either a soul or else some other kind of form. If the latter, then it would be less noble than the sensitive soul, which is absurd since souls are the most noble natural forms, and specific form is related to general form as act to potentiality, from which it follows that a specific form must be more noble than the general form it perfects. If the former, then that added soul would be either capable or incapable of cognition. If incapable, it would be less noble than the sensitive soul, which is absurd. But if it is capable of cognition, it will cognize as either a sensitive or intellective power. Since a horse or dog cannot understand, however, it must be sensitive--but then it would not be distinct from the sensitive soul it supposedly differentiates, which is absurd.

Buridan's fourth argument proceeds to attack the pluralist claim that though really distinct, the vegetitive or sensitive souls found in different creatures are specifically the same:

(4) If the vegetitive soul had the same nature in human beings, horses, and fish, then it would nourish in the same way, and produce similar flesh and similar limbs in those creatures possessing it, which is plainly false.

In his final argument, Buridan points to what he regards as the main problem with the pluralist position. Although we must argue to the specific diversity of substantial forms on the basis of a diversity in operations, he says, "one does not argue to a diversity of substantial forms on the basis of any specific diversity in operations at all" (QDA 2.4, p. 54). That is so for this reason:

(5) Not every operational diversity is attributable to specific difference. Thus, we do not argue from diverse operations in the intellect (for example understanding, willing, apprehending), in the vegetative souls of plants (for example, nourishment, growth, foliation, bearing fruit), or even from diversity in the natural dispositions of elements (for example, the cooling and moistening capacities of water), to diversity of substantial forms.

On Buridan's view, the pluralists' mistake lies in always inferring substantial from operational diversity, when not every operational diversity is attributable to specific difference. Buridan himself regards operational diversity as an indicator of substantial diversity, but his inferences are constrained by the more fundamental metaphysical principle that forms of a superior degree and greater actuality subsume, in their more noble operations, the operations of lesser forms--in the way that a mixture is said to retain the qualities and capacities of its predominant elements (QDA 2.4, pp. 54-5).(7) The soul-body inherence relation is thus not many-one but one-one, since one soul can have a variety of operations, some of which are more noble than others.

Although Buridan is surely following Aristotle on the question of how many relata are on the soul side of each soul-body relation,(8) he is also motivated by considerations of parsimony. In the corresponding question in his QDA 3 treatment of the intellective soul,(9) he reasserts the subject identity principle on the grounds that "it would be pointless to posit more than one soul if everything could be explained by just one" (QDA 3.17, p. 192),(10) One consequence of this is that language improperly implying the existence of a plurality of souls needs to be reformulated so that "the soul is said to be intellective to the extent that it is naturally suited to understand [anima dicitur intellectiva secundum quod innata est intelligere], sensitive to the extent that it is naturally suited to a sense, vegetative to the extent that it is naturally suited to nourish, and locally motive to the extent that it is naturally suited to move a body locally" (QDA 3.17, pp. 192-3). Likewise, Buridan finds that language used to refer to animate capacities must be carefully interpreted so as to avoid falling into the pluralist trap of assuming that distinct capacities inhere in really distinct essences or natures. Thus,

we say that Brunellus is Brunellus and horse and animal and living thing and body through his same essence and nature. And when we say that sensitive being [esse sensitivum] is in Brunellus through his nature as an animal and not as a living thing, we understand by this that "An animal is sensitive" is true per se and in the first instance, and not "A living thing is sensitive." So that an essential or first predication of terms is understood by "being in something in itself" [inesse secundum quod ipsum], either immediately or of this kind, just as "multiplication" is expounded in many ways. So that [that is, the latter] expression was not about real inherence [non erat de reali inhaerentia]. (QDA 2.4, p. 56)

Buridan accordingly concedes that there is an order of predication between the various natural capacities of the soul and the soul itself conceived as sensitive, moving, living, and so on, but denies that such distinctions are ontologically significant in the sense that they entitle us to posit distinct entities. This is for the straightforwardly nominalistic reason that merely predicational distinctions do not make real distinctions.

What is the basis, though, for this definitional or predicational sense in which the various powers of a single soul may be said to be distinct from each other? The final two principles advanced in QDA 2.7 are intended to answer this question.

C. The Definitional Distinction Principle. Founded upon Aristotle's assertion that the various parts of the soul, though incapable of existing separtely, remain distinct in definition,(11) Buridan's third principle is presented as a claim about how we are to understand the terms "vegetative," "sensitive," and so on: "Aristotle's second conclusion is that the names 'sensitive' and 'vegetative' attributed to a horse are not synonymous, but differ in definition, because there is one definition according to which we understand the soul to be the principle of sensation and according to which it is called sensitive, and another according to which we understand the soul to be the principle of nutrition, and according to which it is called nutritive, and so on for the other [definitions]" (QDA 2.7, p. 91). Buridan argues that although the powers of the soul are not really distinct,(12) we do impose different names (for example, "sense," "intellect," "vegetative soul") to signify them as diverse operations, in accordance with the principle that active and passive potentialities take their proper denomination from their operations (QDA 2.5, pp. 64, 66).(13) Such powers are said to be distinct in reason or distinct in definition, since their names signify the same thing "according to different natures [secundum diversas rationes]" (QDA 2.5, pp. 63-4).(14)

A definition, says Buridan, "must explicate the concept of the defined term" (QNE 6.3.118vb). Still, the concepts of defined terms may differ while still suppositing for, or referring to, the same thing:

I say that the same thing is conceived by exceedingly different concepts, either because of the different properties found in it, or because of [their] diverse connotation (whether extrinsic or inhering in it). For this reason, the same thing is properly signified by names belonging to the ten categories. And so it appears that concepts still possess an original distinction on the part of the things signified, though not always on the part of the things which they signify, or for which they supposit, but more often on the part of [their] connotation.(15)

The possibility of terms such as "vegatative soul" and "sensitive soul" having different supposits or referents is ruled out by the subject identity principle. As Buridan states, "I believe . . . that the soul in a horse is singular, and that there is no vegetative soul in it distinct [that is, really distinct] from the sensitive soul, nor sensitive soul distinct from the vegetative" (QDA 2.4, p. 48). The expressions "vegetative soul" and "sensitive soul" are therefore connotative terms having the same referent (for example, horse), but making that referent known in different ways.(16) Buridan's theory of connotation (often called "appellation" in propositional contexts) is an important device from an ontological standpoint. As L. M. de Rijk has suggested, it functions "to make our different modes of thinking the same thing explicit," while avoiding the danger of Platonism which lies in "hypostasizing accidental features" of substances.(17) In the case of the single-substance soul, the features Buridan wishes to avoid hypostasizing are not accidental but essential, namely, the definitive operations of the soul variously conceived as sensitive, living, and so on. To this end, the theory of connotation grounds the language he uses to refer to different psychological operations without committing him to the view that those operations must inhere in different things. What Buridan avoids multiplying by means of the definitional distinction principle are souls.

D. The Homogeneity Principle The final principle introduced by Buridan in QDA 2.7 concerns the manner rather than the mode of inherence. The homogeneity principle states that the sensitive and vegetative souls of nonhuman animals are composed of quantitative parts having the same nature [composita ex partibus eiusdem rationis], like the form of air. This Buridan offers as the metaphysical basis for claiming that the parts of the soul "receive the predications of the whole to the extent that they are quidditative predicates" (QDA 2.7, p. 93; cf. QDA 3.17, pp. 192-3): it is because substantial predicates apply to each quantitative part of homogenous entities that we can say that each part of air is air, each part of water is water, each part of an animal is an animal, and each part of a horse is a horse.

But in the case of the sensitive and vegetative souls, what is it, exactly, that is homogenous? The answer may be found in Buridan's discussion of the extensionality principle. The animate capacities of plants and nonhuman animals conceived as remote potentialities must be homogenously extended throughout their entire bodies, since, as we saw above, even the foot of a horse would see but for the mediating qualitative disposition necessary for seeing. Notice, however, that the homogeneity thesis would be false if "animal" or "horse" were taken as signifying those dispositions or physical organs through which the soul happens to operate, since these organs are composed of heterogenous and dissimilar quantitative parts. Thus, Buridan argues that if we say that an animal "is substantially constituted by prime matter and a single substantial form not having parts substantially dissimilar and belonging to diverse natures," then the term "animal" is truly a substance term which does not signify or connote arrangements of organic matter such as we find in the eyes and ears of living things (QDA 2.7, p. 94).

Buridan offers two arguments on behalf of the view that the terms "animal" and "horse" are nonconnotative substantial terms by which we conceive of an animal or a horse as a composite of matter together with a single soul having homogenous parts. First, if God were to separate, per potentiam divinam, a matter-soul composite from the organic dispositions through which it happens to operate, and preserve it separately, only on the substantial term view could "animal" be truly predicated of the remaining composite; whereas if it were a term connotative of the qualitative dispositions through which the soul happens to operate, or of the soul conceived as an entirety, it would not be true to say of the remaining composite that it is an animal (QDA 2.7, p. 95). Second, in an argument originating from Aristotle's remarks about animals that can survive physical division,(18) it might look as if such animals are really two or more animals: for (1) once divided, the names used to signify their parts will stand for something living, sensing, and subsisting per se--and everything of that sort is an animal; and (2) if the parts of an animal will be animals tomorrow, surely they are animals now (QDA 2.7, p. 96).(19) But Buridan observes that construing "animal" as a substantial term provides an innocuous way of conceding the truth of the second consequence; for "animal" may be truly predicated both of distinct substances and distinct quantitative parts of the same substance in the primary sense that each is a body-soul composite, though not in the secondary and connotative sense that each is a whole substance having distinct quantitative parts (QDA 2.7, pp. 96-7).

By way of contrast, Buridan also discusses how the terms "animal," "horse," and so forth function when construed as connotative rather than substantial terms. Here the homogeneity principle no longer applies, because if "animal" is connotative of the animal taken as a whole, it cannot be predicated of each of its quantitative parts prior to their actual physical division: by "whole being" Buridan understands "that which is a being and not part of another being," and by "whole substance," "that which is a substance and not part of another substance" (QDA 2.7, pp. 97-8). On this view, says Buridan, if we call the foot of a horse A and the rest B, "it is obvious that B is not a horse," although it immediately becomes a horse once A has been cut off (QDA 2.7, p. 98).(20) The reason is that being "whole" or "part" signifies not only some thing, but also that thing's being somehow related to something else. Thus, if the term "animal" connotes totality, Buridan concludes that one would be committing the fallacy of figure of speech by arguing, "Whatever B is now, it was that before," or "B is now an animal; therefore, it was an animal before." This is because B has changed not in what it is, but in how it is related to another thing, in this case to (what was) another integral part of the whole animal (QDA 2.7, pp. 98-9).

The change in truth-value of the proposition, B is now an animal, is rooted in an important feature of Buridan's ontology. What kind of change would make that proposition false at one time, but true at another? There is no change in the supposition or reference of its constituent terms, since on both occasions of its utterance, the subject B refers to the horse minus a foot (the latter being designated as A), and the predicate "animal" to mobile, animate things. But there does appear to be change in what is signified secondarily or connoted by the term "animal" (recall Buridan's assumption that "animal" is being used here as a connotative and nonsubstantial term). This is because "animal" connotes a mobile, animate thing taken as a whole, and that connotation fails in the first instance, that is, when A is still joined to B. One must be careful, though, since no thing either comes into or passes out of existence as a result of this change: "B is now an animal" is true in the second instance only because of a change in the way B is related to something external to it. The question this raises for nominalists such as Buridan is how to explain changes in truth value that do not arise from the generation or corruption of anything, but merely from relational changes. If we assume that the world is austerely furnished to begin with, how are we best to describe subsequent rearrangements of the furniture?

As Calvin Normore has argued, Buridan resolves this problem by embracing realism about modes, which are qualities or accidents that define not what a thing is, but how it is.(21) Such relational changes are regarded as sufficient to ground changes in connotation. Buridan notes, for example, that relational terms may connote "another thing" either inherent in, or extrinsic to, the things for which they supposit:

Sometimes it happens that a relative concrete term not only signifies or connotes the thing for which it supposits, and the thing to which the comparison is being made, but also connotes another thing either inhering in some [one] of them, or perhaps sometimes extrinsic to them. For example, if I say, "Socrates is similar to Plato," the term "similar" not only signifies and connotes Socrates and Plato, but also connotes the quality according to which he is similar to him. And so if I say, "Socrates is equal to Plato," the term "equal" connotes, besides Socrates and Plato, their magnitude. And if I say, "Whiteness inheres in a stone" or "Form inheres in matter," then the word "inheres" connotes the disposition added apart from the form and the matter, namely, the inseparability [of this disposition], as was stated in another [that is, the immediately previous] question. Likewise, if I say, "Socrates is at a distance from Plato," the term "is at a distance" connotes another thing apart from Socrates and Plato and extrinsic to Socrates and Plato, namely, the intermediate dimension by which Socrates is at a distance from Plato.(22)

Although the proposition "B is now an animal" contains no relational terms, Buridan's assumption that "animal" functions in it connotatively suggests that we have in the above discussion the right model for understanding its change in truth-value. Thus, the term "animal" may be said to signify an animate, mobile thing, but also to connote it in some way, namely, as a whole. What it connotes is the spatial continuity of its integral parts, something which Buridan, oddly enough, takes to be extrinsic to the thing possessing it.

Buridan's unusual conception of spatial continuity is best explained, I think, by another passage in which he says that there are three ways in which "something, while remaining the same, is able to be differently disposed, such that contradictory predicates are verified at different times of it, that is, of the term suppositing for it, or such that the same predicate would be affirmed and denied at different times of that term."(23) Only one of these three ways could apply to "B is now an animal," however, and that is the first, which Buridan describes as follows:

The first way is, if the predicate is connotative of something extrinsic to it [sit connotativum alicuius extrinseci], then it is possible for that to happen on account of the existence or nonexistence, or on account of another change, of the extrinsic thing. For example, a man is a father if his son exists, and without him existing, he is not a father. And a man is rich if riches are joined to him [si sunt divitiae sibi applicatae], and poor if they are lost or joined to another. And body A is next to body B if there is no other body or space between them, and it is remote or more remote if there is a lesser or greater body between them. And to be differently disposed on account of another in this way does not require any change in it or in its parts.(24)

The spatial continuity of the integral parts of an animal, that is, the fact that there is no other body between them, is the extrinsic how or mode connoted by the term "animal." That connotation fails for "B is now an animal" as long as B remains spatially continuous with A, because the term "animal" connotes the spatial continuity of the integral parts of its referent. Once A has been physically separated from B, however--that is, once there is some "body or space between them"--the connotation holds, since A is no longer one of the spatially continuous parts of the animal. The conclusion Buridan reaches in QDA 2.7 is that although B "is not different than it was before, it is differently disposed, for being 'whole' or 'partial' not only signifies being something, but also being disposed or not disposed in some way to another thing" (QDA 2.7, p. 98).

E. Summary. Buridan's account of how nonhuman souls inhere in their bodies is given in terms of four metaphysical principles: (1) the extensionality principle, which states that material souls, be they vegetative, sensitive, or appetitive, are extended throughout the entire body of animals and plants; (2) the subject identity principle, which states that the various 'souls' we attribute to the same animal are actually just different powers belonging to a single soul inhering in a single body; (3) the definitional distinction principle, which contends that the terms which are supposed to reflect such differences in psychological operations (for example, "sensitive soul," "living thing") must be understood connotatively, that is, as making the same referent known in different ways; and (4) the homogeneity principle, which states that material souls are composed of quantitative parts having the same nature and existing continuously with the body, though not identical with its particular material arrangements. We may call the conjunction of (1)-(4) Buridan's materialist theory of psychological inherence.(25)


Human Souls. In QDA 3.17, Buridan likens the metaphysical proximity of human souls to their bodies to the way in which God is said to be present to the world:

I imagine that just as God is present to the whole world [assistit toti mundo] and to each of its parts principally and immediately, so in a certain way is the human soul immediately present to the whole human body. And yet there would be a difference, since God is not a form inhering in the world, but the human soul informs the human body and inheres in it. (QDA 3.17, p. 192)(26)

At the risk of explaining the obscure by the more obscure, Buridan does make the point here that the human soul-body relation presents a special problem. Besides being "immediately present" to it, how is it that an immaterial and indivisible whole actually inheres in a material and divisible whole?

Buridan's broad strategy for solving this problem is to appeal to the medieval distinction between being definitively in a place and circumscriptively in a place.(27) According to this distinction, the intellective soul of a human being would be said to inhere definitively but not circumscriptively in its body, that is, such that it is present to its body whole in whole and whole in part, rather than whole in whole and part in part.(28) The latter is the mode of inherence exhibited by material forms such as the sensitive souls of nonhuman animals and the vegetative souls of plants.

But positing a distinct mode of being in a place offers only a starting point for Buridan's dualist account of psychological inherence, because he also wishes to assert the subject identity and definitional distinction principles with respect to the intellectual soul, and he obviously cannot do this by presenting them in a package along with the extensionality and homogeneity principles.(29) The more specific aim of his dualist theory is therefore to explain how it is possible for a single immaterial substance possessing different powers to inhere in a single physical body.

Buridan outlines his view in reply to Averroes' argument that it is impossible for indivisibles, such as the human intellect, to inhere in divisible subjects, such as the human body. This argument "can be set out deductively," he says, in three steps:(30) (1) If an indivisible existing intellect inheres in a divisible body, then it must inhere either (a) in each part of that body, or (b) in some part of that body and not another. (2) It cannot inhere in one part and not in another, because then "it could not be consistently attributed to each part and quantity" of that body (not[1b]). (3) Likewise, it cannot inhere in each part of that body, since as an indivisible, it will have to be taken as a whole (not[1a]). Because it is inconsistent with the requirement that the intellective soul be predicable of each part of its material subject, (1b) is rejected.(31) Buridan is more interested in (1a), however, since it was the rejection of that premise that led Averroes to conclude that the immaterial part of the intellect is transcendent.

Why does Averroes resist the idea that an immaterial soul could inhere as a whole in each part of its body? Buridan suggests that the immanent dualist conception of inherence gives rise to a number of seeming absurdities:(32)

(A1) The same thing would as a whole be moved and at rest simultaneously. Proof: if your foot is at rest and your hand is moving, your soul would be moved as a whole with the motion of your hand, and at rest as a whole with your resting foot.

(A2) The same thing would as an entirety be moved by contrary motions simultaneously. Proof: if you move one hand to the left and the other to the right, your soul would be at a distance from itself, which is impossible.

(A3) Your foot would understand, because the intellect would be present in it as a whole. Proof: the principal operation of the intellect is to understand, and your intellect as a whole is present in your foot.

(A4) Your foot would be a human being, because the human substantial form would be present in it as a whole. Proof: the intellect is the substantial form of the whole human being, and your intellect as a whole is present in your foot.

(A5) Substantial forms would travel from subject to subject as the parts of a body change. Proof: the intellect as substantial form is present in each part of the body, but some of these parts can come to be or pass away without the corruption of their original subject.

Buridan rejects, however, Averroes' conclusion that the human intellective soul can only be a transcendent substance, firmly asserting the contrary thesis that "your intellect, by which you understand, inheres in your body or your matter" (QDA 3.4, p. 31). This obligates him to reply to (A1)-(A5).(33)

In response to (A1), Buridan points out that although the intellect is moved in the hand and at rest in the foot simultaneously, "this is not a contradiction," because "those motions do not inhere in it, nor are they commensurably related to it" (QDA 3.4, pp. 35-6). As a model for the way in which human intellects are related to their bodies, Buridan appeals to the doctrine of real presence in the Eucharist:

When it is said that it [the intellect] is moved by contrary motions, we can speak of this just as we speak of the body of Christ in the consecrated host when one priest carries the body of Christ to the right and another to the left. For the body of Christ is neither moved in itself, nor by a motion inhering in it, just as the size of the host does not inhere in it. (QDA 3.4, p. 35)

Buridan assumes here that there are two kinds of inherence relation: "real" inherence or inherence proper, the relata of which are commensurably related to each other;(34) and definitive inherence, the relata of which are noncommensurably related. The commensurability of properly inherent relata follows from their mutual, finite extension: one thing commensurably inheres in another just in case both are extended; otherwise, their mode of inherence is noncommensurable. Immaterial substances such as the intellectual soul would therefore be present in extended bodies in accordance with the second, noncommensurable, mode of inherence.

The notion of noncommensurable or definitive inherence is further discussed in Buridan's reply to (A2). The Real Presence again provides the explanatory model, this time for understanding how a noncommensurably inherent substance could be in two places at once:

To the second counter-instance, it is said that [the intellect] is not at a distance from itself [non distat a se] because it is not in the hand or foot commensurably [commensurabiliter], since it is not extended by the extension of the hand or foot. And it is not absurd for the same thing to be noncommensurably and wholly in different places at a distance from each other, although this would be by supernatural means, as the body of Christ is simultaneously in paradise and on the altar (for the body of Christ in the host on the altar is not commensurate with the magnitude of the host, but [as a whole] in each part of the host, even if the parts are at a distance from each other--and it is not on that account at a distance from itself). And so in the same way, the intellect is somehow in the hand and foot, and in neither commensurably, since it is not extended in any of those members. (QDA 3.4, p. 36)

Following his reply to (A1), Buridan's reply to (A2) makes use of the fact that noncommensurably inherent forms cannot be moved in conjunction with the motions of any commensurable part(s) of their material subjects. Inherent forms can be moved only if they are part in part present in their subjects.

Buridan replies to the worries in (A3) about a foot becoming an understanding thing, or even becoming a human being (in [A4]), by examining the logic of the terms "total" (totale) and "partial" (partiale). If the phrase, "total understanding" (totale intelligens), is properly expounded as "that which is not part of another understanding," he says, a foot cannot be called a total understanding because it is part of another whole understanding, namely, the human being (QDA 3.4, p. 36). Likewise, nothing is called a human being "in familiar and ordinary speech except the whole substance, that is, that which is not part of another substance" (QDA 3.4, p. 36). The Averroists' mistake in (A3)-(A4) is to multiply substances by the (infinite) number of divisible parts belonging to their material subjects, rather than by each of those subjects taken as a whole. But it does not follow from the assumption that the intellect is whole in each part of the human body that each part of the human body is a whole intellect. That would be the fallacy of division.

The final Averroist argument, (A5), claims that substantial forms wholly present in each part of their material subjects would migrate from subject to subject as the extended parts of their bodies change (the souls of blood donors, for example, would come to exist in the bodies of their recipients). Buridan replies by pursuing the suggestion in his reply to (A2) that noncommensurable inherence has a supernatural cause:

It will be said that the way in which the intellect inheres in the human body is not natural but supernatural. And it is certain that God could supernaturally not only form something not derived from a material potentiality, but also separate what has been so derived from its matter, conserve it separately, and place it in some other matter. Why, then, would this not be possible as regards the human intellect? (QDA 3.4, p. 37)

In other words, because supernaturally inherent forms such as the human intellect are not subject to material change, they are not themselves divided when the extended parts of their bodies are divided. Rhetorical questions aside (Why wouldn't this be possible as regards the human intellect?), it is puzzling to find Buridan pinning such a crucial metaphysical doctrine on divine omnipotence.(35) But the picture is more complex than first appears.

Buridan's reply to (A5) actually contains two claims: first, non-commensurable inherence is not a natural state of affairs, meaning that it cannot be explained by appealing to the same principles which govern the inherence of material forms; and second, there is nothing contradictory in supposing that God could create an indivisible, unextended substance and put it in matter. Buridan is making the subtle but important point here that although no naturalistic model can explain how human souls inhere in their bodies, we have no a priori reason for supposing that only naturalistic models need apply. This is really a claim about where a theory of noncommensurable or definitive inherence should begin, rather than some ad hoc appeal to the miraculous. In the case of human souls and their bodies, Buridan is very clear about the explanandum:

[There is] the truth of our faith, which we must firmly believe: namely, that the human intellect is the substantial form of a body inhering in the human body, but not derived from a material potentiality, nor materially extended, and so not naturally produced or corrupted; and yet it is not absolutely everlasting, since it was created in time. Nevertheless, it is sempiternal hereafter [sempiterna a parte post] in such a way that it will never be corrupted or annihilated, although God could annihilate it by his absolute power. (QDA 3.3, pp. 22-3)

Again, since the human soul is not an extended or material thing, neither the extensionality principle nor the homogeneity principle can explain its mode of inherence in the human body. Some other principle or principles must be found to support the view that the various powers of the human soul are one in subject and yet distinct in definition.

Now that we know where to begin, what about the explanans of noncommensurable inherence? Here Buridan is less forthcoming, for two, not unrelated, reasons. First, he is generally wary of encroaching on territory outside the traditional domain of an Arts Master, often mentioning his reluctance to treat a question because it would be more properly addressed by theologians.(36) Given Buridan's belief that noncommensurable inherence should be understood on the model of real presence in the Eucharist, it is not easy to see how any philosophical discussion of the former could avoid becoming embroiled in the theological controversy surrounding the latter.(37) Second, perhaps also because he was an Arts Master, Buridan sees natural philosophy (including psychology) as committed to naturalistic explanation, which for him requires the construction of demonstrative arguments based on evident premises. Where such arguments are lacking, he is inclined to indicate their absence and leave it at that, rather than to engage in a priori metaphysical speculation.

He takes a similar approach to the question of the human soul's status as an immaterial form:

Although this thesis [that the human intellect is not a material form] is absolutely true, and must be firmly maintained by faith, and although the arguments adduced for it are readily believable [probabiles], nevertheless, it is not apparent to me that they are demonstrative, [drawn] from principles having evidentness [evidentiam habentibus] (leaving the faith aside), unless God with a grace that is special and outside the usual course of nature could make it evident to us, just as he could make evident to anyone the article of the Trinity or the Incarnation. (QDA 3.4, pp. 25-6)

Buridan's point here is that since the immateriality of the human intellect is not evident to us, or apparent to our senses, we are in no position to construct empirical arguments about it. God could, of course, make such truths evident to us directly and nonempirically, but then our scientia would not be natural, but revealed.(38)

All of this leaves Buridan with little to say when it comes to explaining how the various powers of the human soul are attributable to a single, unitary subject. Though he argues for this thesis, he does so, as we saw above, on the grounds that it would be pointless to imagine a plurality of souls inhering in a human being when operations such as nutrition, sensation, and understanding can all be attributed to just one.(39) Thus, one and the same human soul may be called "sensitive to the extent that it has been naturally suited to sense," although unlike the sensitive souls of nonhuman animals, the human sensitive power is neither extended nor naturally generated. Rather, it is said to "inform" corporeal and extended matter through an act that "coexists" with the material dispositions of sense organs. The human sensitive soul can thereby remain incorruptible, even if "the corporeal dispositions required for sensing naturally are corrupted" (QDA 3.17, p. 193).

If the human sensitive soul cannot be both incorruptible and extended, however, it also follows from Buridan's account that, except for purely material similarities in the organs through which humans and nonhuman animals operate, sensation in human beings will differ specifically from sensation in nonhuman animals. This will give rise to a certain discontinuity between the two accounts, since our understanding of the internal causes of, say, equine vision will not apply to human vision. Buridan acknowledges this problem and reflects on it:

It is certainly true that there is a great difficulty if we posit just one soul in a human being, for it must be intellective and indivisible, not extended in any way by the extension of matter or subject. And then that unextended sould is [also] a sensitive and vegetative soul. How, then--since sensation is supposed to be materially extended in organs--could it be inherent in an indivisible subject and, as it were, derived from its potentiality? This seems to be miraculous [hoc videtur mirabile], since the only extension form has is extension in its subject. And how could a divisible and extended thing inhere in an indivisible and unextended thing? This seems to be miraculous. And I reply with certainty that it is miraculous, because the human sould inheres in the human body in a miraculous and supernatural way, neither extended nor derived from the potentiality of the subject in which it inheres. And yet it also inheres in the whole body and in each part of it. This is truly miraculous and supernatural. (QDA 2.9, p. 138)

To modern ears, this passage has an unfortunate ring. It strikes us as a capitulation: a philosopher giving up the game because he believes that his subject matter is beyond rational comprehension. Seen in the context of his other remarks about psychological inherence, however, Buridan's claim in the above passage is in fact much more limited. Recall his suggestion above that God could, if He wished, make the immateriality of the human intellect evident to us outside the common course of nature. Buridan is not suggesting here that the inherence of the human soul is utterly inexplicable, but only that it cannot be explained naturalistically, that is, with demonstrative arguments based on premises whose truth is apparent to our senses.(40) He is making only a negative claim about the failure of empirical knowledge in a certain field of inquiry. His remarks do not entail that some a priori mode of knowing might not reveal to us the principle governing the human soul's inherence in its body, though, again, he does not speculate about this. His conception of the miraculous is likewise not absolute, but relative to the epistemic situation of human beings. Thus, when he calls the inherence of the human soul in its body miraculous, he has in mind nothing like the Humean conception according to which miracles are violations or transgressions of the laws of nature, but something more in the spirit of Augustine's remark that a miraculous event "does not occur contrary to nature, but contrary to what is known of nature."(41) I suggest that substituting "outside the common course of nature" for each occurrence of "supernatural," and "not empirically evident" for "miraculous" would provide a reading of the above passage which, though a bit awkward, better reflects Buridan's thinking on the question.


Conclusion. Buridan's hybrid solution to the problem of psychological inherence consists, on the one hand, of a materialist explanation of the relation between nonhuman animal or plant souls and their bodies, and, on the other, of an immanent dualist explanation of the human soul-body relation. In both cases he contends that the various animate functions of a living thing belong to one and the same subject (the subject identity principle), and that such functions are distinct from each other not really but only in definition (the definitional distinction principle). The main difference between his two accounts consists in his assertions that nonhuman souls are extended throughout their bodies (the extensionality principle), and have the same physical nature in each part (the homogeneity principle). The latter two principles do not apply to human intellective souls, which lack extension and hence also integral parts. The human soul is, on the contrary, noncommensurably or definitively present in the body in which it inheres.

Buridan sees psychology as a naturalistic endeavor, concerned with the construction of arguments based on empirically evident premises. This approach has its shortcomings, however, as a means of defending the immanent dualistside of his theory. Buridan appeals to the notion of noncommensurable or definitive inherence in order to avoid Averroes' conclusion that indivisible human souls cannot actually inhere in divisible human bodies. But no naturalistic explanation seems possible for a mode of inherence that is, by his own admission, caused outside the common or usual course of nature. The result is that while Buridan is able to block the Averroist reductio argument that an inherent soul would be moved as an entirety by simulatenous contrary motions, he does so at the significant cost of moving part of his theory beyond the scope of his own explanatory methodology. Understanding the precise relation between the human soul and its body turns out to be a matter best left to theologians, who use the notion of noncommensurable inherence to explain the Real Presence of Christ in the consecrated bread and wine of the Eucharist.

Buridan is well aware of the lack of empirical evidence for dualism, though he does not reach what seems to be the consensus view in contemporary philosophy of mind that dualism is empirically false. Rather, he treats what little evidence is available to him concerning the human soul-body relation as insufficient to establish the truth about that relation's nature. His own conclusion about the nature of this relation is hardly agnostic, of course, but he openly admits that it is not founded upon anything observable in the common course of nature. In that sense, at least, Buridan was a naturalist who understood the limits of naturalistic explanation.(42)

(1) The last of these features distinguises Buridan's view from that of Averroes, who defends the transcendent dualist view that the immaterial and everlasting part of the human soul (which he calls the possible intellect) is a singular entity existing separately from individual human beings, but in such a way that it is simultaneously present to each of them. Much of Buridan's own account of psychological inherence is developed in counter-point to Averroes' Long Commentary on De anima, a work with which he was intimately familiar. See John Alexander Zupko, "John Buridan's Philosophy of Mind: An Edition and Translation of Book III of his Questions on Aristotle's De anima (Third Redaction), with Commentary and Critical and Interpretative Essays" (Ph.D. diss., Cornell University, 1989), 457-505.

(2) Specifically, in QDA 2.4-2.7 (see Peter Gordon Sobol, "John Buridan on the Soul and Sensation: An Edition of Book II of His Commentary on Aristotle's Book of the Soul, with an Introduction and a Translation of Question 18 on Sensible Species" [Ph.D. diss., Indiana University, 1984], 42-105) and QDA 3.3-3.6, 3.17 (see Zupko, "Buridan's Philosophy of Mind," 20-56, 189-98). In the text, citations of QDA 2 and QDA 3 will be followed by page numbers from the editions of Sobol and Zupko respectively. Unless otherwise indicated, all translations in this paper are my own.

(3) See De anima 413b16-24.

(4) Quaestiones Ioannis Buridani super decem libros ethicorum Aristotelis ad Nicomachum (Paris: 1513; reprint, Frankfurt am Main: Minerva, 1968), 6.3.118vb. Hereafter this work will be cited as "QNE."

(5) Buridan later concedes that the intellective soul does in fact use corporeal organs "ministratively" (ministrative) in carrying out its principal operations (QNE 6.3.119ra). This is based on his view that the intellect of the wayfarer cannot (1) think without phantasms or images provided by the faculty of sense, and specifically by the imagination, a cognitive power realized in physical organs, namely, in the heart and the brain (see also QDA 2.23, pp. 383-4; 2.24. pp. 401-2; 3.15, p. 383; cf. De anima 431a16-17); or (2) exercise its power of volition without objects presented to it sub ratione boni vel mali, that is, appearances that are ultimately founded upon sensory images (see also QDA 3.15, pp. 167-8; 3.18, pp. 199-205; QNE 3.1-3.5). The profound dependence of thinking and willing upon the operations of corporeal organs is not expressed more strongly here because Buridan elsewhere maintains the conceivability of the intellective soul operating without corporeal organs. In such a disembodied state, it is said to understand "by God's power and arrangement [ex dei potentia et ordinatione]; QDA 3.6, p. 54.

(6) The nobility of agency over passivity is likewise invoked in an argument on the negative side of QDA 3.1, which asks, Is the human intellect a passive power as regards what is intelligible? "Again, it follows that the vegetative power would be more noble than the intellect, which is false. The consequence is obvious, because (1) it is active in relation to its object; (2) acting is more noble than being acted upon; and (3) that action must be judged more noble whose act is more noble"; QDA 3.1.

(7) Cf. QDA 3.3, p. 24; Iohannis Buridani Quaestiones super libris quattuor De caelo et mundo, ed. Ernest Addison Moody (Cambridge: Medieval Academy of America, 1942), 1.7, pp. 31-5.

(8) See De anima 414b24-415a14; cf. De anima 3.12-13.

(9) QDA 3.17 asks, Is there a single intellective soul in a human being distinct from the sensitive soul? (p. 189). Buridan's arguments in QDA 3.17 are heavily dependent upon QDA 2.4, referring to the latter question on at least five different occasions.

(10) "Frustra ponerentur plures animae si omnes possent salvari per unicam." Cf. QNE VI.3.118va: "And if this kind of predication [that is, of absolute terms] can be preserved of him [God] without anything added to him, it could also be preserved in other things, because it will be otiose to posit a relation in matter, in the soul, or in any other principle at all, other than a soul added to its foundation."

(11) See De anima 413b29.

(12) Notice, however, that the mediating qualitative dispositions or instrumental potentialities through which the soul exercises its operations (discussed in connection with the extensionality thesis above) are really distinct from each other. The reason is that dispositions of this sort inhere in physical organs, from which it follows that, for example, an animal's eyes must be really and not merely conceptually distinct from its ears or nose (as is obvious). See QDA 2.5, pp. 64-7; QNE 6.3.118vb.

(13) Buridan employs a parallel concept, "denomination by the much more principal part" (denominatio a parte valde principaliori), for substance terms. Thus, he argues that despite the change in Socrates' bodily parts over time, Socrates remains the same in the sense that his most principal part, namely, his soul, persists without material or substantial change; Ioannis Buridani subtilissime quaestiones super acto physicorum libros Aristotelis (Paris: 1509; reprinted as Kommentar zur Aristotelischen Physik [Frankfurt am Main: Minerva, 1964]), 1.10.13vb; QDA 2.7, pp. 100-1. Cf. QDA 3.11, p. 125; 3.20, p. 217.

For the imposition of different names to correspond to the different ways of understanding a thing, cf. Sophismata 4, in T.K. Scott, Jr., Sophisms on Meaning and Truth (New York: Appleton-Century-Crofts, 1966), 126 (the Latin text is in Iohannis Buridani Sophismata, ed. T. K. Scott, Jr. [Stuttgart: Frommann Holzboog, 1977], 73-4): "For since I can understand the same thing in many different ways [secundum multas diversas rationes], and, corresponding to these diverse ways, impose different names on it to signify it, therefore, such verbs cause the terms with which they occur to connote the reasons [appellare rationes] for which their names are imposed to signify them, and not only the external things known [res cognitas ad extra], as happens with other verbs." Hereafter, the Latin and English texts will be cited together.

(14) Cf. QNE 6.3.118vb-199ra.

(15) In Metaphysicam Aristotelis quaestiones argutissimae magistri Joannis Buridani (Paris: 1518; reprinted as Kommentar zur Aristotelischen Metaphysik [Frankfurt am Main: Minerva, 1964]), 4.1.13ra-rb.

(16) Cf. William of Ockham, for whom connotative terms primarily signify what they are truly predicable of, but secondarily signify or connote, for example, the abstract concept contained in their nominal definitions. See William of Ockham, Summa logicae 1.10, in his Opera Philosophica 1, ed. P. Boehner, G. Gal, and S. Brown (St. Bonaventure: The Franciscan Institute, 1974), 35-8.

(17) L. M. de Rijk, "On Buridan's Doctrine of Connotation," in The Logic of John Buridan: Acts of the Third European Symposium on Medieval Logic and Semantics, ed. Jan Pinborg (Copenhagen: Museum Tusculanum, 1976), 98-9. De Rijk adds that for Buridan, connotation and appellation differ in the sense that the former (like signification) is a semantic property of terms, whereas the latter (like supposition) occurs only in propositions.

Buridan's primary discussions of connotation and appellation can be found in parts of two treatises of his Summulae de dialectica: Tractatus de suppositionibus, in Maria Elena Reina, "Giovanni Buridano: Tractatus de suppositionibus," Rivista critica di storia della filosofia 12 (1957): 343-8; and in Sophismata 4, in Scott, Sophisms on Meaning and Truth, 109-44; and Iohannis Buridani Sophismata, 59-89.

(18) See De anima 413b20; and note 3 above.

(19) Cf. Buridan's resolution of the sophism, "You ate raw meat today," in Sophismata 4, in Scott, Sophisms on Meaning and Truth, 118-20; Iohannis Buridani Sophismata, 67-8.

(20) The example presented here may have been inspired by the traditional sophism sentence, Animal est pars animalis, which usually introduced the same problem in terms of the relation between Socrates and Socrates' foot. Neither this sophisma, however, nor the closely related Totus Socrates est minor Socrate, is discussed in Buridan's own Sophismata. See Norman Kretzmann, "Syncategoremata, exponibilia, sophismata," in The Cambridge History of Later Medieval Philosophy, ed. Norman Kretzmann, Anthony Kenny, and Jan Pinborg (New York: Cambridge University Press, 1982), 231, n. 79.

(21) Calvin Normore, "Buridan's Ontology," in How Things Are: Studies in Predication and the History and Philosophy of Science, ed. James Bogen and James E. McGuire (Boston: Reidel, 1985), 198-9.

(22) In Metaphysicam Aristotelis 5.9.32va. Cf. 5.8.31rb-33ra (actually 32ra).

(23) Super octo physicorum libros 2.1.31ra. The proposition "B is now an animal" obviously fits into the latter category, since the predicate "is now an animal" is first denied and later affirmed of B, a subject that is itself unchanging.

(24) Ibid., 2.1.31ra-rb. Neither of the two other ways mentioned by Buridan could apply to the case of "B is now a horse." The second way is intended to cover predicates connoting "the situation [situm] of the parts of the thing in relation to each other," and specifically the differing dispositions which result from the internal local motion of the parts of a thing, such that "there is nothing else afterwards which was not there before, and also nothing before which was not afterwards." But none of the examples Buridan gives in this connection--Socrates first sitting and then standing, a spherical object becoming cubical--involves any gain or loss of integral parts. Likewise, the third way applies to predicates connoting qualities which are actually generated or corrupted at different times in a thing, such as whiteness in Socrates. For further discussion of these ways or modes, see Normore, "Buridan's Ontology."

(25) If we were to put a contemporary label on it, we might say that Buridan's materialism has more in common with functionalism than, say, with mind-brain identity theory. For as we saw in his discussion of the extensionality principle, Buridan identifies the souls of plants and non-human animals with the conjunction of their animate powers, rather than with the particular organs or material dispositions through which those powers happen to operate.

(26) There is an uncanny similarity between this passage and another, much earlier passage in which Buridan is reporting the opinion of Averroes. In fact, the only real difference between them is that Buridan asserts, whereas Averroes denies, the actual inherence of the human soul in the human body: "He [Averroes] imagines that just as God is present without distance to the entire world and to each part of it, and yet not inherent in the world or in any part of it, so the intellect is related to human beings, namely, [in such a way] that it inheres in none of them, but is present without distance to each [cuilibet indistanter assistit], even though it is indivisible"; QDA 3.3, p. 22.

(27) The distinction is also used by both Duns Scotus and Ockham to explain the doctrine of transubstantiation. For discussion of this, see Marilyn McCord Adams, William Ockham (Notre Dame: University of Notre Dame Press, 1987), 186-201.

(28) "Our soul is something that exists indivisibly in the entire body and in each part of it"; QNE 6.6.143rb.

(29) The subject identity and definitional distinction principles are asserted with respect to the human intellect in QDA 3.17, pp. 191-6.

(30) See QDA 3.4, p. 30.

(31) For Buridan, this follows from the assumption that indivisible animate forms such as the intellective soul are definitively rather than circumscriptively present in the bodies in which they inhere. The sensitive and vegetative souls are also predicable of each part of their material subjects, but for a different reason: the homogeneity principle guarantees the equal attribution of divisible animate forms to each part of the bodies in which they inhere, so that the integral parts of material things also "receive the predications of the whole to the extent that they are quidditative predicates"; QDA 2.7, p. 93. Cf. QDA 3.17, pp. 192-3.

(32) See QDA 3.4, pp. 30-1.

(33) Buridan actually begins by offering four "naturalistic" reductio arguments against Averroes, but these tend to gainsay rather than directly refute the Commentator's position (QDA 3.4, pp. 32-4). Briefly, Buridan argues that a transcendent intellect would exist extrinsically to the substance it supposedly informs, and could not be numerically many (contrary to the evidence of experience). Hence he argues that it must be unique (likewise contrary to experience), and finally that it would exist before you do, even though it is in a sense your transcendent intellect.

(34) For the term "real inherence," see QDA 2.4, p. 28, quoted in section I above.

(35) Buridan also appeals to supernatural causes to explain the numerical diversity of human intellects in QDA 3.5, p. 44.

(36) One cannot avoid being struck by the number of times Buridan makes this concession in his writings. In psychology, it figures in his discussions of both the sense in which the human intellect is everlasting, and the possibility of cognition after death and in a disembodied state; QDA 3.6, pp. 53-4; 3.15, p. 173. Still, Buridan's expressions of deference to theologians more often than not accompany, rather than replace, his own treatments of so-called matters of faith. See In Metaphysicam Aristotelis 6.5.37ra (on divine foreknowledge); Quaestiones super libris quattuor De Caelo et mundo 1.20, p. 93 (on the existence of a body beyond the heavens); Super octo physicorum libros 4.8.73vb-74ra (on the possibility of a vacuum); and Super octo physicorum libros 8.12.121ra (on the thesis that God sets each of the celestial bodies in motion directly, with an impressed force or impetus): "I state this not as an assertion [assertive], but in order to seek from divine theologians what they would teach me about these matters [and] how they can occur."

(37) For an illuminating discussion of the theological controversy in relation to Ockham, see Adams, William Ockham, 186-201.

(38) Buridan elsewhere allows that there are theological arguments concerning the nature of the soul (for example, that Christ assumed a "complete and entire humanity," including a sensitive soul), but he says that these produce a "great faith" in him, rather than knowledge; QDA 3.17, p. 192.

(39) See note 10 above.

(40) Cf. In Metaphysicam Aristotelis 12.9, where Buridan explores possible relationships between the number of celestial motions and the number of the intelligences: "And another conclusion is posited: that there are many more separate substances than celestial spheres or celestial motions, namely, great legions of angels. But those [legions] cannot be proved with demonstrative arguments arising from what has been sensed [ista probari non possunt rationibus demonstrativis habentibus ortum ex sensatis]"; 12.9.73ra.

(41) See David Hume, An Enquiry Concerning Human Understanding, 10.1; and Augustine, City of God, 21.8. A useful overview of medieval strategies for explaining mirabilia is provided by Bert Hansen, Nicole Oresme and the Marvels of Nature (Toronto: PIMS, 1985), 50-73. For discussion of the epistemic consequences of Buridan's conception of the miraculous, see my "Buridan and Skepticism," Journal of the History of Philosophy 31 (April 1993): 21-50.

(42) An abridged version of this paper was read a session on cognitive science in the fourteenth century at the Twenty-Seventh International Conference on Medieval Studies, Western Michigan University, May 1992. I would like to thank Marilyn Adams, Jenny Ashworth, and Calvin Normore for their helpful comments and suggestions.
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Author:Zupko, Jack
Publication:The Review of Metaphysics
Date:Mar 1, 1993
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