Society for Ancient Greek Philosophy
APA Pacific Division
Los Angeles, California
March 26, 1998

The Receptivity of NouV in De Anima 3. 4

Joseph M. Magee, University of St. Thomas, Houston, Texas

In his essay, "Intentionality and Physiological Processes," Richard Sorabji claims that Aristotle maintains a sharp distinction between the formal and material causes of sensation.(1) To that end, Sorabji interprets a cluster of Aristotelian formulae about sensation as descriptions that exclusively pertain to perception's material cause. This material cause, according to Sorabji, is the process that the sense organ undergoes during an episode of sensation. These Aristotelian formulae fall roughly into three main groups: the claim that what perceives receives form (which I will call the formal reception thesis), the claim that what perceives receives form without matter (which I will call the anahylic reception thesis(2)), and the claim that what perceives becomes actually like or such as its object from being potentially like or such (which I will call the likeness thesis). According to Sorabji, when Aristotle asserts any of these three theses, he is referring to one and the same physiological process by which the organ becomes actually and literally black or white, hot or cold, dry or fluid.

This physiological account, however, is not Aristotle's only explanation of sensation. Sorabji tells us that Aristotle does have another doctrine concerning the sense power becoming aware of its object, but it is expressed in the quite different terms of actual identity. In DA 3.2 (425b26-426a26), Aristotle explains sense perception in terms of his general theory of causation in Physics 3.3, where actual teaching and actual learning are said not to constitute two activities, but one and the same activity that goes on in the learner.

The application to sense perception of this causal theory is that the activity of a sound in working on one's hearing and the activity of hearing are not two activities, but one and the same activity, and located not in the organ but in the sense (en tei kata dunamin).(3)

Sorabji, however, immediately makes the point that "this doctrine about the activity of sense tells us nothing about whether the organ takes on sound."(4)

Sorabji notes that two of these allegedly physiological descriptions, i.e. the formal reception thesis and the likeness thesis, are linked " 429a15-16, where it is said that if thinking is like perceiving, the thinking part of the soul must be able to receive form and be potentially such as its object."(5) Although this passage is part of Book 3, Chapter 4 of the De Anima, a chapter devoted to explaining how the faculty of thought, nouV or mind, is separate from the body, these descriptions nevertheless have no application beyond the physiological sense that Sorabji claims they have. They are merely the beginning of Aristotle's treatment of nouV, "the first tentative comparison"(6) with sensation according to a physiological description, but a comparison he soon abandons. Although Aristotle does say that nouV possesses forms (e.g. in thinking of a stone (431b28-432a1)), according to Sorabji, nouV does not receive such forms, much less are they received without matter.

The stone is not described as 'matter' and its form is not spoken of as 'received,' probably because these words have expressed a doctrine about the sense-organ, and thinking does not in the same way involve an organ, in his view. Instead, the comparison is with the doctrine which does not concern the organ but the sense, that the activity of sound is in the sense and is not merely such as, but identical with, the activity of hearing."(7)

For Sorabji, then, the faculties of sense and of thought, on the one hand, and the organs of sense, on the other, cannot be described in the same terms. The formal reception thesis and the anahylic reception thesis cannot apply to nouV since they only apply to organs, and nouV has no organ. On the other hand, although the faculty of thought, like the sense faculty, does become one with its object, it does not do so, however, by receiving the form of its object. What does receive form, i.e. the sense organ, merely becomes such as, but not identical with its object. At least part of Sorabji's claim that expressions describing the physiological processes of sensation but having no application beyond the physiological, then, requires that Aristotle does not describe nouV in the same terms. If either the formal reception thesis, the anahylic reception thesis or the likeness thesis applies to nouV, then that fact undermines Sorabji's claim that these descriptions apply exclusively to sense organs.

I believe, however, that Sorabji is mistaken about Aristotle's description of nouV. Even after the introductory remarks about the similarity between sensation and thought, Aristotle, in his considered position in DA 3.4, continues to maintain that the faculty of thought receives its objects. While it is not as obviously asserted as the thesis that the objects of thought are without matter, nevertheless, the formal reception thesis clearly applies to the activity of nouV since it provides a key to the first main argument of the chapter. Aristotle's account of nouV, then, incorporates an Aristotelian formula that Sorabji claims applies only to sensation, and only to sensation's material cause. Consequently, because this descriptions applies to a faculty that Sorabji admits has no organ, he cannot maintain his restriction of the formal reception thesis to the sense organs alone.

Although he does not engage in an extended exegesis of DA 3.4, an analysis of this chapter, from which Sorabji draws his example of the coupling of the formal reception principle and the likeness principle, shows that nouV is indeed receptive. While many translations of this chapter do not make the receptive nature of nouV obvious, other translators and commentators clearly do consider this fact to be so obvious as to be unremarkable. Charles Kahn, for instance, simply translates a key passage of this chapter as follows: "hence nous has no nature other than this: the capacity (to receive noetic form)...."(8) However, since there is disagreement among scholars as to whether nouV receives forms, the point deserves some analysis and justification.

In analyzing this chapter, one first finds Aristotle arguing throughout that nouV is in some significant way non-bodily, which he describes as unmixed (429a18), not mixed with the body (429a24), separable (429b6), and separable from the body (429b23). Aristotle in this chapter seems to give three main arguments for this thesis. First, however, he proposes the comparison between thinking and perceiving, the comparison which Sorabji calls "tentative" and one that Aristotle later abandons. Aristotle tells us that "if thinking is analogous to perceiving, it will consist in a being acted upon by the object of thought..."(429a12)(9) and goes on to say that the part of the soul by which it thinks "...then, must be impassive, but receptive of the form..."(429a15). As a consequence of being like perceiving, thought is a "being acted upon" by its objects in some sense, and this implies that it, like sense, is still impassive and "receptive of form." Aristotle can maintain that nouV, like sense, is both a "being acted upon" and "impassive," since, as he explained in 2.5, the "being acted upon" that characterizes sense, is a special kind that should receive a special name (417b12-17). It is this distinct aspect of sense that merits the label "impassive," and this distinct aspect applies to nouV as well. If the comparison with sensation as receptive of form is merely tentative, as it is on Sorabji's interpretation, the point of the comparison, then, seems only to show that nouV is impassive in a manner similar to the sense faculty.

What follows this comparison is the first of the three argument that nouV enjoys a special kind of separateness from the body. Aristotle argues that nouV is "unmixed" based on the fact that its range is limitless. For this argument to succeed, however, it is necessary that nouV receive its objects.

The intellect, then, since it thinks all things, must needs ... be unmixed with any.... For the presence of what is foreign to its nature hinders and obstructs it...(429a18-20).

Aristotle apparently believes that, given that the intellect has all things for its objects, it is necessarily unmixed with any of them. However, if one supposes, as Sorabji does, that being an object of the intellect has nothing to do with the intellect receiving it as an object, then Aristotle's support for this claim seems baffling. Aristotle's added premise apparently makes the counter-factual claim that, if the intellect had a foreign nature present, it would be hindered and obstructed, which apparently we are to believe is not the case (429a20). Hence, the sense of "hinder" and "obstruct" here conveyed is that of short-circuiting, i.e. the simple non-functioning of the intellect. The principle seems to say that if the intellect had a foreign nature present, then it would just not work at all.

Reading 429a20 this way, it seems to be a rather perplexing statement. What makes it so perplexing is the phrase "the presence of what is foreign to its nature." One could understand more easily how the presence of something foreign could be a hindrance if Aristotle were talking about an organ of a knowing power, e.g. the eye. A mote of dust could be in the eye, and this could hinder its performance. However, Aristotle evidently is talking about a power that has no organ (429a26). The intellect, precisely because it has no organ, cannot have something foreign present, in the sense of intruding from an extrinsic source, and yet be hindered. For if something is present to this non-bodily power, then either it is constitutive of itself (in which case it is not foreign), or it is the intellect's object (in which case the intellect is not hindered). However, one and the same thing cannot be both foreign to the intellect and a hindrance to its operation. If the presence of something foreign that hinders the intellect is an impossible situation, then it is utterly mysterious why Aristotle should say that it is the reason why the intellect, which knows all, is unmixed.

The fact that 429a20 does not seem to make much sense in itself is our first indication that something is wrong. D. W. Hamlyn interprets this argument of DA 3.4 (almost) exclusively in terms of the identity thesis whereby the intellect becomes its object. He, like Sorabji, sees Aristotle's formula about receiving form without matter as intelligible only with regard to sense organs(10). Noting that 429a16 identifies two formulae as points of similarity between sense and intellect (i.e. the formal reception thesis and the likeness thesis), he believes that the first is so tied to Aristotle's account of a physiological process in the sense organ, that it is unintelligible when applied to nouV. Thus, he reads this argument for the intellect being unmixed as follows:

The intellect must be unmixed with anything, since it thinks everything, and is thus, according to the formula, potentially like all things without being actually such. It must therefore be solely potential, if it is to think all things, and is before thinking nothing actual. If it contained anything actual it could not become this, as it must do according to the formula if it is to think it.(11)

Hence, for Hamlyn, the claim that the intellect is unmixed means that it is nothing actual. This conclusion follows from the two premises: "whatever knows is potentially, but not actually like its object" and "the intellect knows all things."

This interpretation has a certain plausibility since it captures part of Aristotle's thought on knowing powers. However, two points speak against it being Aristotle's whole intent. First, it does not really take into account 429a20 which I have tried to show is troubling and needs explaining. According to Hamlyn, the line merely asserts that the intellect, in order to become like its object, cannot already be actually like its object. Second, Hamlyn's construal makes Aristotle's point that the intellect is nothing actual before it thinks to be just a repetition of the claim that the intellect is unmixed. For Hamlyn, this is not surprising since he reads the separation and unmixed character of the intellect in the weakest way possible.(12) However, for Aristotle, the fact that the intellect is nothing actual until it thinks is some further point beyond the point that it is unmixed.(13)

An examination of the overall structure of Aristotle's argument shows the inadequacy of this reading of the text, especially of Smith's translation of 429a20. The argument consists of two universal premises and a universal conclusion. The first premise is as follows:

1. Whatever foreign nature that is present to a power, hinders (i.e. prevents the operation of) that power.
The conclusion claims:
3. The intellect is unmixed.

If we assume that "unmixed" is equivalent to "does not have a foreign nature present," it is clear that the only hope Aristotle has for making a valid syllogism is to claim as the minor premise:

2. No intellect is hindered.(14)

However, there are still two problems with the argument as thus presented. First, what is the justification for the major premise; why should "the presence of something foreign" entail being hindered? Second, although all he would have to assert as evidence for the claim that nouV is not hindered is that the intellect actually knows anything at all, Aristotle's actual minor premise is "nouV knows all things." The argument, then, seems to require a stronger connection between something not being present when the intellect knows all things and the implication that the intellect is unmixed.

Only if we posit that nouV is receptive of its objects can we make sense of the connection Aristotle sees between the universal capacity of nouV and its status as unmixed. Aristotle's logic requires that he connect the intellect with being unmixed by a denial that it is hindered, which he seems to think he accomplishes by claiming that nouV knows all things. Only on the supposition that knowledge is a kind of reception would it be necessary for Aristotle to claim that nouV knows all things in order to deny that it is hindered. Given this supposition, however, if the intellect were to know less than all things, it would be hindered from receiving some objects, and so be restricted in some way. Any other sense of knowledge, e.g. as simply becoming identical with the object (without receiving it), could take place without necessarily being a knowledge of all things, and still the knowing power would not be hindered. Thus, the only way Aristotle's actual words could measure up to the demands of his argument is if knowing is a kind of receiving. Consequently, the claim that "nouV knows all" has to be equivalent to "nouV receives all." This is also equivalent to the claim that there is nothing that nouV does not receive, i.e. nouV is not hindered. "To hinder," then, as Aristotle is using the term, does not mean "fails to function" as Smith's translation would lead one to believe, but rather means "impedes or blocks the reception of something."

Understanding Aristotle's use of "hinder" in this sense gives the necessary justification for the connection between knowing all things and being unmixed. The universal scope of nouV implies that it lacks the hindrance that it would have if something were present, only because nouV receives what it knows and is thereby united with its object. Thus, because there is in fact no restriction on what nouV receives, Aristotle concludes that nouV does not have the hindrance of something being present and, as it were, displacing its object. For Aristotle, it is in virtue of the intellect's receptivity that there is an implied equation between having nothing present and being unmixed, an equation that does not apply to the senses. For although the senses are relatively unhindered, the fact that they do not receive all forms, i.e. know all things, but only the forms of their proper objects, is to be explained by the fact that they are mixed, i.e. that they have organs.

Aristotle's connection between the intellect's universal receptivity and it having nothing present also makes sense of his other conclusion, i.e. that nouV has no nature other than to be in potency prior to knowing (429a22-24). The intellect has no nature beyond its receptive capacity, since that would prevent the reception of some form (and so it would not receive them all). Instead, it is merely in potency to receiving its objects and to being united with them, since to receive a form is the same as to be united with its object. Both of these points deserve a fuller elaboration which is not possible here. For the present, however, we can conclude that on the force of the logic of the argument, nouV, indeed, is receptive of form.

Given that Sorabji is highly critical of the ancient and medieval commentary tradition on other interpretive points, it is not surprising that we find a member of that tradition, Aquinas, disagreeing with him on his understanding of nouV. Aquinas took 429a20 to mean that the presence of some nature in a knowing faculty hindered that faculty in respect of receiving that nature. As he says in his commentary on the De Anima, "Anything that is in potency with respect to an object, and able to receive it into itself, is, as such, without that object."(15) The intellect, however, is unrestricted with respect to what it can know, for it can know all things, and so in itself it lacks all of the natures which it receives. "...If the intellect were restricted to any particular nature, this connatural restriction would prevent it from knowing other natures".(16) Thus, according to his interpretation, since the intellect receives the forms of all bodies, it must lack the form of any body. Aquinas, therefore, concludes that the intellect is spatially separate, that is, it has an operation in which the body does not share. Even though Aristotle's version of the argument does not claim that the intellect knows all bodies, Aquinas' interpretation nevertheless accords with the overall structure of Aristotle's argument by understanding the intellect to be receptive.

The interpretation of nouV as receptive gains further support if one examines the Greek. In Greek, 429a20 reads: "parempfainomenon gar kwluei to allotrion kai antifrattei." What is essential for Aquinas' interpretation is that to allotrion be translated as the object of kwluei and antifrattei as the translation of William of Moerbeke, from which Aquinas worked, renders the passage: "For what appeared inwardly would prevent and impede what was without."(17) In this translation, "what was without" (extranem) is William's rendering of to allotrion, and in Latin it is clearly the direct object of "prevent and impede" (prohibebit et obstruet), William's rendering of kwluei and antifrattei respectively.(18) It seems that Aquinas' reading, prompted by William's translation, then, fits more with the thrust of Aristotle's argument, since "hinder" in the argument, as noted above, carries with it the notion of blocking the reception of something. For, only if nouV is receptive is Aristotle's claim that nouV knows all things evidence that the intellect is unimpeded with respect to what it receives (to allotrion). The reading that Aquinas and William give the passage highlights the fact that Aristotle has not changed his mind with regard to the claim at 429a15 that thinking, like sensation, involves the reception of form.

In addition to the added coherence that it gives to the argument of DA 3.4, there is other evidence that Aristotle meant antifrattei to convey the sense of impeding the reception of something and to allotrion as its object. Of the six other genuine uses of antifrattein in Aristotle's work, four of them concern something (the earth or some celestial body) blocking the light of the sun or the moon in an eclipse, but all of them require that the word mean "block the passage or reception of something."(19) A typical example can be found at Posterior Analytics II, 2 (90a18) where Aristotle explains that in an eclipse, the earth hinders the light of the moon. "What is an eclipse? The privation of the moon's light by the interposition of the earth."(20) In this passage, Aristotle clearly uses antifrattein to signify that something blocks or stands in the way of moonlight. In this context, the verb does not, nor could it, mean simply "to prevent the operation of something," as Smith's reading of 429a20 would require. Since Aristotle uses the verb antifrattein to describe the obstruction and non-reception of an object of observation elsewhere, it lends further support to the reading of 429a20 given by William and interpreted by Aquinas where to allotrion is the object of antifrattei, and what appears inwardly (paremfainomenon) is not something foreign.

From the foregoing, it should be apparent that, for Aristotle, the faculty of thought is legitimately characterized as being receptive of its objects. To construe Aristotle as holding that it is not renders a significant part of DA 3.4 to be of highly questionable internal coherence, since it makes it seem that he is claiming that something foreign might intrude into a power that has no organ and render that power inoperable. Moreover, failure to acknowledge the intellect's receptivity renders what is clearly supposed to be an explanation (mind is unmixed because it knows all things) otiose and virtually unrelated to the logic of his argument. Finally, the denial of the claim that nouV is receptive forces onto Aristotle's Greek a sense that is totally inconsistent with other uses of the same words. For these reasons, it seems best to hold that, at least through his first argument in DA 3.4, Aristotle did not begin his treatment of nouV with a merely tentative comparison between the faculties of thought and perception according to the formal reception thesis, only to later abandon the claim that this thesis holds for nouV. Rather, throughout this part of the chapter, Aristotle believes that nouV is receptive since its receptivity is essential for the validity of his argument and the consistency of his thought.


1. Richard Sorabji. "Intentionality and Physiological Processes: Aristotle's Theory of Sense Perception." In Essays on Aristotle's De Anima, edited by Martha C. Nussbaum and Amelie Oksenberg Rorty. (Oxford: Clarendon Press, 1992). 211-212

2. I use the term anahylic reception instead of other terms that suggest themselves (e.g. immaterial reception of form) to avoid the connotation of a theory about awareness or intentionality that Sorabji adamantly denies is Aristotle's. See his "From Aristotle to Brentano: the Development of the Concept of Intentionality." In Festschrift fur A. C. Lloyd: on the Aristotelian Tradition, edited by H. Blumenthal and H. Robinson. Oxford Studies in Ancient Philosophy (Oxford: Oxford University Press, 1991).

3. "Intentionality and Physiological Processes," p. 213.

4. Ibid.

5. Ibid., p. 212.

6. Ibid., p. 213.

7. Ibid.

8. Charles Kahn, "Aristotle on Thinking," In Essays on Aristotle's De Anima, edited by Martha C. Nussbaum and Amelie Oksenberg Rorty. (Oxford: Clarendon Press, 1992). 376.

9. Aristotle. De Anima. tr. J. A. Smith in The Basic Works of Aristotle. Ed. Richard McKeon. (New York: Random House, 1941).

10. Aristotle's De Anima. Books II and III. Translated by D. W. Hamlyn. (Oxford: Clarendon Press, 1968). Translation and commentary. p. 136.

11. Ibid.

12. "The intellect is distinct from the body in the way already suggested, that it is a potentiality and has no organ" (137) "...the intellect is dependent for its existence on the senses" (138).

13. "...wste mhd' autou einai fusin mhdemian all' h tauthn, oti dunaton." (429a21). "dio oude memicqai eulogon auton tw swmati." (429a24)

14. Thus the argument is in the second figure, AEE:

(x)(Px => Hx) All that has something present is hindered.

(x)(Ix => ~Hx) No intellect is hindered.

:. (x)(Ix => ~Px) Therefore, no intellect has something present.

15. Aquinas, Thomas. Aristotle's De Anima in the Version of William of Moerbeke and the Commentary of St. Thomas Aquinas. Translated by Kenneth Foster and Sylvester Humphries. (New Haven and London: Yale University Press, 1951). Book III, lecture 7, no. 680.

16. Ibid.

17. Intus apperens enim prohibebit extranem, et obstruet.

18. In Smith's translation, quoted above, to allotrion modifies paremfainomenon; thus the phrase reads in English "the presence of what is foreign to its nature". As far as I can tell, this reading is equally grammatical, but makes less sense given Aristotle's argument.

19. The four dealing with eclipses are APo I, 31 (87b40), APo II, 2 (90a18), De Coelo II, 13 (293b25) and Meteor. I, 8 (345a29) The two others are Meteor. II, 8 (368b10) and De Juvent. 5 (470a13).

20. ti estin ekleyiV; sterhsiV fwtoV apo selhnhV 'upo ghs antifraxewV.