a. The Opinion of Others and the Weighing and Putting Together of it

55. It is said of the first [by Aquinas] that it is known by natural reason.

56. This is shown in two ways: in one way by authorities from the Philosophers who asserted this, and only as something known to natural reason; in another way by adducing the natural reasons from which it follows.

α. Proof by Authorities from Philosophers

57. As to the first point [n.56]: Aristotle On the Soul 2.1.412a19-b6 defines the soul as ‘the act of an organic physical body’ etc. And at 3.4.429a10-11 he says, “About the part of the soul by which it knows and is wise,” where he seems to posit the intellective soul as at least a kind or species of soul previously defined in general terms.

58. Again, all philosophers have commonly put ‘rational’ in the definition of man as his proper difference, meaning by ‘rational’ that the intellective soul is an essential part of man.

59. Nor, in short, is any noteworthy philosopher found who denies this, although the accursed Averroes in his fiction in On the Soul III com. 5, 36 - a fiction that is nevertheless intelligible neither to him nor to anyone else - posits a certain separate intellective substance that is conjoined [to man] by the medium of phantasms. This conjunction neither he nor any of his followers has been able to explain, or to save by means of it, the fact that ‘man understands’. For, according to him, a man would formally be only a sort of excelling irrational animal, though because of an irrational and sensitive soul more excellent than the other animals.

β. Proof by Natural Reasons

60. On the second point [n.56]. No a priori or a posteriori reason can easily be found for the intended conclusion save one taken from man’s proper operation, since form is made known by proper operation as matter is made known by change. So, argument for the intended conclusion is taken from the operation of understanding as follows: understanding is the proper operation of man; therefore it comes from man’s proper form; therefore the intellective soul is the proper form of man.

61. But this reason has an objection against it, that the intellect, according to them, is related only passively and not actively to the act of understanding. Therefore the proposition ‘proper operation comes from proper form’ does not prove that the intellective soul is the proper form of man, since this operation, according to them, does not come from the intellective soul but from the intelligible object or, according to others, from the phantasm.

62. Therefore I form the argument from that operation in another way as follows: man understands formally and properly; therefore, the intellective soul is the proper form of man.

63. The antecedent here seems sufficiently clear according to the authorities from Aristotle On the Soul 3.4.429a21-24 and Ethics 1.6.1098a3-4, 1.7: that ‘to understand’ is the proper operation of man; but operation, as it is distinct from action or making, exists formally in the one operating and does not proceed therefrom to something else. Likewise, Ethics 10.7.1177a12-b1, 8.1158b7-32, 9.1179a22-32, places man’s happiness in an act of understanding, and it is manifest that happiness is in man formally; therefore the operation in which happiness consists is in man formally.

64. But it is necessary to prove the antecedent by reason (against him who impudently denies it), and this by taking in the antecedent ‘understanding properly speaking’, by which I mean ‘an act of knowing that transcends the whole genus of sense knowledge’.

65. This antecedent, therefore, is proved in one way as follows: man understands by a non-organic act of knowing; therefore, he understands properly.

The consequence is plain from the reason already set down [n.63-64], that a proper act of understanding is knowing that transcends the whole genus of sensation; but all sensation is organic knowing, from On the Soul 2.1.412a21-b9, 2.11.423b31-42a7. The proof of the antecedent of this enthymemeThe antecedent is “man understands by a non-organic act of knowing” and the argument it is the antecedent of is an enthymeme because the premise that a non-organic act is an act of understanding properly is left unexpressed. This premise itself is proved by the statements that understanding properly is knowing that transcends the whole genus of sensation, and that sensation does not so transcend because it is the act of an organ and an organ is tied to a determinate class of sensibles. The inadequacy of this argument is shown in what follows. ² is that an organ is determined to a definite genus of sensibles, from On the Soul 3.426b8-23, and this for the reason that it consists in a proportion between the extremes of the genus. But we experience some knowledge in ourselves that does not belong to us according to such organ, because then it would be determined precisely to the sensibles of a determinate genus, the opposite of which we experience; for we know by such act the difference between any genus of sensibles and something else that is not anything of the genus; therefore we know each extreme (the consequence is plain according to the Philosopher when he argues about the common sense in On the Soul 2.11.423b31-4a7).

66. But objection is made here:

First, that organic knowledge is that which is present according to a determinate part of the body; but the knowledge about which it is argued that we distinguish by it sensibles from non-sensibles is present first in the whole body, and so it does not come through any organ properly speaking. However, it does not transcend in perfection the whole genus of sensitive knowledge, because it is present first in the whole body, and consequently it is as material as that which is in the whole part by part; for thus is a property of the whole as material as that which is in the whole part by part.

67. Second, the assumption is denied, namely that the act is not present according to any organ; for it is present according to the organ of imagination. The proof of this is that when this organ is damaged knowledge is impeded. Nor is the proof sound [n.65] about the determination of the organ to a certain genus, because imagination extends itself to all sensibles.

68. However, the first objection [n.66] is excluded by something touched on there [n.65], because we discriminate by the act [sc. of understanding] between the whole genus of sensibles and something that is outside that whole genus.

69. Nor is the proof sound [n.67] that when the organ of imagination is damaged knowledge is impeded; for this happens because of the order of these powers in their operation, and not because understanding is exercised through the medium of this organ.

70. The principal antecedent [nn.65, 62], that there is some immaterial knowledge in us, is proved in another way: no sensitive knowledge can be immaterial,     therefore etc     .

71. This term ‘immaterial’ is frequently used by the Philosopher in the issue at hand, but it seems ambiguous. For it can be understood in three ways relative to the issue at hand:

Cognition is immaterial either because it is incorporeal in the following way, that it does not come through a bodily part and organ; and then it is the same as the proposition already set down about non-organic knowledge.

Or it is immaterial in another way, that it is in no way extended, and then it states more than ‘non-organic’ does; for although all organic cognition is extended because it is received in something extended, yet not only so; because if it were received in the whole composite first, then since the whole composite is extended the operation would still be extended.

In a third way its immateriality can be understood in relation to the object, namely that it regards the object under immaterial ideas, that is, to the extent it abstracts from the here and now and the like, which are said to be material conditions.

72. Now if immateriality in the second way were proved, the proposed conclusion would be obtained more than from a proof of it in the first way. But it does not seem it can thus be proved (save from the conditions of the object that the act regards), unless perhaps by reflection, because, as much as the act of this knowing is not reflexive on itself, we experience ourselves reflecting back on it. And     therefore , it is from the object of the act that a proof of the antecedent is finally reached.

73. In this way: we have in ourselves some knowledge of the object under the idea under which there cannot be any sense knowledge of it; therefore etc     .

74. The proof of the antecedent [n.73] is that we experience in ourselves that we know the universal actually.

75. And we experience that we know being or quantity under an idea more common than is the idea of the first sense object, even as regards the highest sense soul.

76. We also experience that we know the relations consequent to the natures of things, even non-sensible things.

77. We experience too that we distinguish the whole genus of sensible things from anything that is not of that genus.

78. We even experience that we know relations of reason (which are second intentions), namely the relation of universal, of genus and species, of opposition and other logical intentions.

79. We experience too that we know the act by which we know these intentions and know that by which the act is present in us, which is by an act that reflects back on the direct act and is receptive of it.

80. We experience too that we assent to certain propositions, as the first principles, without possibility of contradiction or error.

81. We experience too that we come to know the unknown from the known by a discursive process, such that we cannot dissent from the evidence of the discursive process or from the knowledge inferred.

82. Each of these ‘knowings’ is impossible for any sense power;     therefore etc     .

83. But if someone stubbornly deny that these acts are present in man, and deny that he experiences them in himself, one should not dispute with him further but should say to him that he is a brute thing. Just as one should not dispute with someone who says ‘I do not see color there’, but should say to him ‘you need senses because you are blind’. So we we experience these acts in us by a certain sense, that is, by an interior perception. And therefore, if someone denies them, one must say that he is not a man because he does not have the vision that others experience.

84. The proof of the assumption, namely that ‘none of these acts can be present according to any sense power’ [nn.82, 73], is because the universal in act is known with as much indifference [to any particular] as the thing thus known can be asserted of every singular in which it is found to be preserved. Sense does not know in this way [n.74].

85. But this is more evident from the second point [n.76], because no power can know anything under an idea more universal than its proper object (as sight does not know anything under an idea that is indifferent as to color and sound); therefore the knowledge that is of something under an idea more common than any posited object, even of the highest sense, cannot be any sensation.

86. The third point [n.77] proves the same, because no sensation can distinguish its first sense object, that is, its most common object, from what is not of that sort, because neither can it distinguish both the extremes.

87. About relations consequent to things not mutually sensed by each other, or are non-sensible in relation to things sensible [n.78], the answer is plain from the same point [n.86], that the senses have no power for them. And this is much plainer about those relations that are called relations of reason, because a sense cannot be moved to know something that is [not?]There is no ‘not’ in the Latin but it seems to be necessary, unless ‘sensible qua sensible’ means ‘sensible under the idea of sensible’, for sense perceives the sensible thing and not the idea of what it is to be a sensible thing. ³ included in a sensible object as sensible. The relation of reason is not included in anything as it is existent; but sense is of the existent as it is existent. And hereby can also be proved the principle too about a universal act, because to be an existent as it is existent is repugnant to a universal in act.

88. The other point, about reflection back upon act and power [n.79], is proved by the fact that a quantum is not reflexive on itself.

89. The other two points, about composition and assent to composition, and about discursive reasoning and assenting to the evidence of discursive reasoning [nn.80-81], are proved from relation of reason, because they are not without relation of reason.

90. The consequence of the first enthymeme [n.65] is proved as follows: if such an act is in us formally (since it is not our substance because sometimes it is present and sometimes not present), then one must grant there something properly receptive of it; but not anything extended, whether it is an organic part or a whole composite, because then the operation would be extended, and it could not be such as it is said to be about objects such as they are said to be; therefore it must be present according to something nonextended and that is formally present in us; but that cannot be without the intellective soul, because any other form is extended.

91. Or the consequence can be proved in another way, by going to the condition of the object of the act; because any form lower than the intellective form, if it has an operation, has it precisely in respect of an object under ideas opposite to those that have been stated. Therefore, if we have an operation about an object under those ideas, it will not be in us according to any form other than an intellective one; therefore it is in us according to an intellective one. Therefore an intellective form is in us formally, otherwise we would not be operative formally according to that operation.

92. The same thing can be proved from the second human operation, namely the will, because man is lord of his acts such that it is in his power to determine himself by his will to this thing or its opposite, as was said in Lectura II d.25 n.94. And this fact is known not only from the faith but also by natural reason. Now this indetermination cannot be in any sense appetite, either organic or extended, because any organic or material appetite is determined to a certain genus of desirables that is agreeable to it, such that when the genus is apprehended it cannot not be agreeable nor can the appetite not desire it. Therefore the will by which we thus indeterminately will is an appetite that is not of any such form, namely material form, and consequently it is an appetite of something that surpasses every such form. We set down the intellective form as of this sort, and then, if that appetite is formally in us, because desiring is so as well, it follows that that form is our form.