Knowledge is a fact. What is the process of knowledge, and what is the value of knowledge, are the important considerations. What makes a thing knowable, how do we know it, and what is the validity of our knowledge? An answer to these questions gives the psychology and epistemology of knowledge. There is a sentence in one of the works of Aquinas that contains the factors involved in the problem of knowledge. "There are," says he, "but three requisites for knowledge, namely, the active power of the knower by which he judges of things, the thing known, and the union of both."{1} Before we can have knowledge, there must be something knowable, some one capable of knowing, and both the knowable object and the knowing subject must come into some union or relation. Knowledge is only realized when the object and the subject enter into a determined relation. These elements are admitted by all philosophers as necessary for a theory of knowledge. We shall now consider their organic connection in the theory of St. Thomas, and also the objective value of our knowledge as resulting from this theory.
It is a Scholastic axiom that all knowledge or every cognition is in the knower through an assimilation of the knower to the known.{2} The nature of this assimilation and how it is brought about forms the problem of knowledge for the Scholastics. This assimilation runs through all knowledge and is its basis. There are two sorts of knowledge distinct in kind -- sensory and intellectual. From the external senses that receive the forms of material things, without matter indeed, but yet with many material conditions, up through the internal senses which retain and combine the images of these forms, the human intellect, the angelic intellect, the Divine intellect, there is a steady rise and the attainment of more perfect knowledge on the basis of immateriality. The assimilation or likeness that is brought about between the knowing power and the object is not simply according to the nature of the object in itself, but rather according to the nature of the knowing faculty. Hence the object is in the knower not according to its natural form as it exists in its real being, but through a representative form, through a form which the Scholastics called intentional. This representative or intentional form was also known to them as species. The species in itself, as an entity, agrees in nature with the power in which it is, in representing it agrees with the object it stands for. It is sensible or intellectual (species sensibilis, species intelligibilis) according to the knowing faculty -- senses or intellect. "For sensible vision as well as for intellectual, two things are required, viz., the power of vision and the union of the seen with the one who sees. For there is no actual vision except the things seen be in some way in the one seeing."{3} This cognitive assimilation further demands from the object to be known some degree of immateriality, for the concept of knowledge and the concept of materiality are opposites.{4}
This is a brief statement of the question of knowledge as set forth by St. Thomas. It can be reduced to three fundamental principles, that we shall examine in detail, and thus arrive at a clearer view of the psychology of this system and the critical value given it by Aquinas.
These principles are: First, knowledge is the result of the union of the subject and object; second, the object known is in the knowing subject according to the nature of the knower; third, the perfection of knowledge is in proportion to the immateriality of the knowing subject. In other words, the essence of knowledge consists in the intrinsic presence of the object in the knower in such a way that the knower is aware of it, and this recognition is due to an act that contains in itself the object as a known terminus. In knowledge the knowing subject and the known object must be one; this unity is attained by an assimilation based on immateriality. The words unity, assimilation, immateriality, comprise the whole question.
The truth of the first principle is beyond doubt, if we do not seek to determine the nature and origin of this resemblance or assimilation. It is a fact that we possess knowledge, and it is equally clear that we have not the object according to its natural or physical being, for the nature of the knowing power forbids this -- hence there must be some means by which the object is made knowable and the union between the knower and the known takes place. This assimilation or union is of the essence of knowledge; the object must be in the knower in such a way that it makes the subject know the object, and this is what is meant by saying that it is in the knower representatively. There is a two-fold similitude or likeness: there is one according to the nature of things and there is a representative one. This latter "likeness of the knower to the known is required for knowledge."{5} The subject and the object concur in one common action -- the known object must be present to the knowing subject, according to the nature of the knowing subject, and the knowing subject by its activity must respond to the specific determination of the object.{6}
The part of the object in this union is to determine the knowing faculty which of itself is indifferent and indeterminate;{7} and this determination is brought about, as noted above, by some representative presence of the object, which the Scholastics called by the special name of species. This species is synonymous with the words forma and similitudo, and is a special determination coming from the object by which the subject is aroused and directed to know the object itself. When the mind is not engaged in any actual cognition, it is inactive and indetermined; the object acting on the mind determines the mind to know it. The element by which the object is in connection with the subject, which is its substitute, is called by the Scholastics species impressa; excited by this determination the mind acts, and the result is given in the species expressa by which the mind knows the object.
This word species is of constant occurrence in the Scholastic theory of knowledge, so an understanding of it will obviate misinterpretations, and will likewise simplify the problem as presented in these terms. It is hardly necessary to say that the word species has no community of doctrine with the floating images of Democritus and Epicurus which Aristotle rejected, and which is not to be found in the best Scholastic writings.{8} The true meaning is simply this: the mind is affected or modified by objects acting on the knowing power, sense-organ or intellect. The mind is in a peculiar attitude or modified to perceive an object, The species has no independent existence, but is bound up with the state or condition of the mind viewed at the time of cognition; it is due to the action of objects on sense-organs or intellect. There are no pre-existing species, for the "knowing soul is in potentia to the species which are the principles of sensation, as well as to the species which are the principles of intellection . . . In the beginning, it is in potentia to all the species by which it understands."{9} It is the condition by which activity-sensory and intellectual, is actualized. The intellect is actually intelligent through the intelligible species, as the sense is actual through the sensible species.{10} "The intelligible species is the formal principle of intellectual operation, as the form of any agent is the form of its specific operation." Through it the object becomes known. The mind does not perceive it primarily, but it is the means of perception -- "that which is understood is the very concept of things existing outside the mind."{11} It is the object that is understood, but by means of the species. "The intelligible species is not that which is understood but that by which the intellect understands."{12} The object is not inferred from the species, as though it were an intermediate representation, but the species is simply the means that brings about the union of subject and object resulting in knowledge. The species expressa was sometimes called intentio. Very often this word was made an adjective -- intentionalis -- in conjunction with species. This intentio in us is "neither the thing itself which is understood, nor is it the very substance of the intellect, but it is a certain likeness conceived in the intellect of the thing that is understood."{13} It was also known in intellectual knowledge as verbum mentale. It is the terminus of the intellectual activity aroused by the intelligible species. This word intentional was used to show in what way the object was present to the knowing subject, to show the nature of the resemblance between the knower and the known. It offsets the view that the object is present in knowledge in its real and physical being; it is present really, but not according to the condition in which it is found in nature. This leads us to our second principle: The object known is in the knower according to the nature of the knower.
We have now seen the meaning of the word species, and its fundamental importance in the Scholastic system. The first principle gives the nature of the species from the point of view of the object, as representative of the object; the second principle views the nature of the species from the standpoint of the subject, as it exists in the knower. It exists in the knower according to the nature of the knower.
The second principle strictly taken is but a corollary of the first rightly understood, for if knowledge is but the union of the subject and the object, both must be of the same nature or reduced to it before the union can be effected. "All knowledge is according to some form, which is the principle of knowledge in the knower. This form or species can be viewed in a twofold light: in its relation to the knowing subject, and also in its relation to the object whose likeness it is, In the former it arouses the knowing faculty to cognitive activity, and in the latter it points out a definite object of knowledge. Hence the manner of knowing a thing is according to the condition of the knower, in whom the form is received according to his nature. But it is not necessary that the thing known exist according to the nature of the knower or according to that manner by which the form, which is the principle of knowing, has existence in the knower."{14} The manner of knowing must be that of the knower, but the thing itself in rerum natura need not be one with this mode, for knowledge is not "by means of identity, but by means of a certain representation; whence it is not necessary that the nature of the knower and the known be the same."{15} This conformity of the subject and object is "not a likeness of conformity in nature but a likeness of representation only, as we are reminded of some man through a golden statue."{16} In fact, "the perfection of knowledge consists in this, that the thing be known to exist in that nature in which it is, and not that the nature of the thing known be in the knower.{17}
The truth of this principle is emphasized indirectly or negatively by St. Thomas when he criticises the views of those who went astray on this point. Some of the ancient philosophers misapplied the axiom -- 'like is known by like" -and landed in a position the extreme opposite of that held by Plato. They understood this principle to mean that the "soul which knows all things is naturally made up of all: earth that it may know earth, fire to know fire, and so of the rest."{18} This of course would make the soul corporeal, since it knows corporeal things; in fact, it would make it a compound of all things since it can know all things, and not only made up of the elements these philosophers considered as contained in their first matter. If their interpretation of this principle were true, then the possibility and diversity of knowledge would be at an end.
St. Thomas likewise sets aside the theory of Plato regarding this principle. "Plato," he says, "seems to deviate from the truth in this matter, for since he considered all knowledge to take place by means of likeness, he believed that the form of the known is of necessity in the knower in that manner in which it is in the known."{19} This led Plato to conceive the independent reality of general concepts to bring about the requisite conditions for knowledge as they appeared to him; ideas and not corporeal things would be the object of our intellectual representations, according to Plato. This theory results in an arbitrary knowledge, neglecting things as they are and failing to account for our knowledge of corporeal things.
St. Thomas rejected these two views because they did not accord with what he conceived to be the basis of conformity between object and subject. His critical spirit is shown by his putting aside the Naturphilosophen and Plato, and embracing a principle contained in the book De Causis: That everything received is received according to the nature of the receiver.{20} This principle is important for the theory of knowledge, embracing as it does our second principle. We know the object directly, as noted before, and the object also has the prior activity in knowledge, yet it must adapt itself to the conditions of the knowing power. Subject and object must be so intimately connected as to form one sole principle of knowledge according to the axiom: Ab utroque notitia pantur a cognoscente et cognito. In this union the object comes under the conditions of the knowing power, for the object is knowable only when it has entered the field of consciousness by being assimilated by the subject.{21} This assimilation makes it an integral part of the knowing power, and thus a partaker of its nature. The subject also is modified by the object to the extent, that it is knowing under this condition and for this object. From the psychological point of view this principle presents no great difficulties, but it is important in the question of the objectivity of knowledge.
The third principle flows easily from the two preceding. If knowledge depends on the assimilative union of object and subject, and if the object is known according to the nature of the knower, it follows readily that the knowableness of the object depends on its immateriality. "The concept of knowledge and the concept of materiality are opposites"; "the more immaterial things are, the more knowable they are."{22} "This principle or axiom is very important; in a way, it underlies the whole question of knowledge, it is the condition that makes a thing knowable, and makes knowledge the possession of a particular class of beings. Immateriality, in general, is the capacity a thing has to be itself and to become something else. In knowledge, the object must be immaterial in itself or else immaterialized, and the subject must be immaterial -- the object is assimilated and the subject assimilates. This double aspect is brought out clearly by St. Thomas' immateriality on the part of object and subject. The distinction between a knowing being and one that does not know is based on immateriality. The non-knowing has simply the one form of its own being, whereas the knowing is capable of receiving the form of another thing, for the species or form of the known is in the one knowing. The non-knowing can be assimilated but cannot assimilate; the knowing has the power to assimilate and thus become more and more. Hence the nature of the non-knowing is more restricted and limited, whereas the knowing has greater amplitude and extension. It is for this reason Aristotle said the soul is quodammodo omnia. It is because of the universality of the knowing power, that matter, which is the principle of individuation and restricts the form to one condition or result, cannot be admitted into it; rather in proportion to the absence of materiality will the knowledge be the freer and more perfect.{23} If the soul were naturally determined in one direction, to one set of activities, all its operations would be influenced by this specific bent, just as all things taste bitter to an unhealthy tongue. The soul must then be capable of adjusting itself to receive the various cognitions we know it actually possesses, it must have in its nature none of those things it seeks to know and can know.{24}
St. Thomas has knowledge graded on the scale of immateriality -- the knowableness of the object and the knowing capacity of the subject rest on the same basis. A thing is knowable in proportion to its immateriality, and a subject knows in proportion to the extent of the immateriality of its nature. There is a passage in the Summa Theologica, Part I, q. 84, a. 2, that brings out this fact clearly. Knowledge is per formam, and its concept is the opposite of the concept of materiality. When forms exist materially only -- immersed in matter -- there is no power of knowledge, as is the case in plants; but in proportion as the form of the thing is possessed more immaterially, the more perfect is the knowledge. Thus the intellect which has the form of the object freed from matter and all individuating conditions is more cognoscitive than the senses which possess the fonn, without matter it is true, yet with material conditions. Even among the senses themselves this principle is verified, for vision is the most cognoscitive because it is the least material; likewise among concepts the degree of immateriality regulates the degree of perfection. There is no break in the application of this axiom, it leads straight up to the highest knowable and the most perfectly knowing -- God Himself. The idea of immateriality as here understood, contains the idea of activity; potentia and matter are pratically one and are the opposites of immateriality and actuality.{25} In God there is an utter absence of potentia and matter. He is characterized by the possession of their contraries, and thus he is especially knowable and knowing. "Since God, therefore, is the opposite extreme of matter, since He is entirely immune from all potentiality, it follows that He is especially knowable and especially knowing."{26} There are objects that are immaterial in themselves and are knowable so far as they are concerned, and there are objects that do not possess this quality but must be brought to this condition before they are propria of the mind. God, the spirit world -- including Angels and the souls of men, our own thoughts and the thoughts of others as thoughts, come under the first class; the second class embraces what we ordinarily understand by material objects. We shall take up the question of God shortly. That Angels come under this term is evident to all who accept the doctrine about Angels -- "some essences are sine materia as separated substances which we call Angels."{27} The mind knows itself, and the content of the mind together with the mind itself is immaterial. From the fact that we perceive ourselves to understand we know that we have an intellectual soul, but to understand the nature of this soul there is need of a careful consideration -- a subtilis inquisitio. In this latter quest many have erred through a misunderstanding of the principle -- like is known by like. They perceived that they had a knowledge of material things and at once concluded that these objects were present to the soul materially, not recognizing that the concepts of knowledge and immateriality are opposites. Plato, as St. Thomas notes, rightly conceived the soul to be immaterial and its knowledge to be likewise immaterial, but his explanation of this truth was not satisfactory. He introduced unnecessary elements to account for this doctrine; he did not give the intellect the power to render a material object immaterial, but held there were immaterial ideas independent of the object, and that it was these ideas or forms the mind knew. This theory is unlike that of St. Thomas, who says, "everything intelligible is immune from matter in se, or is abstracted from matter by the operation of the intellect,"{28} yet it is the actual recognition of immateriality as a requisite for knowableness.
The knowledge the soul has of itself emphasizes further this requisite of immateriality. St. Thomas holds that we have a two-fold knowledge of the soul -- an actual and habitual one. We can simply know of its existence, and we can also know of its nature -- two distinct points, "for many know they have a soul who do not know what the soul is,"{29} do not know its nature. The soul becomes aware of itself through its acts -- "one perceives that, he has a soul, and lives, and is, because he perceives himself to feel and understand and to exercise the other functions of a life of this nature."{30} This reveals its existence; "what the nature of the mind itself is, the mind can only perceive from a consideration of its object."{31} From a knowledge of its object, the soul comes to know its own nature. "Our mind can not so understand itself that it can immediately apprehend itself, but from apprehending other things it comes to a knowledge of itself . . . From the fact that the human soul knows the universal natures of things, it perceives that the species by which we understand is immaterial; otherwise it would be individualized and thus never lead to a knowledge of the universal."{32} The soul knows the universal, the proper object of the intellect is the essence of material things, this essence is immaterial, and the soul perceiving this immaterial essence recognizes its own immaterial nature, for operation follows being, the act is in accord with its source.
The idea running through these principles is -- knowledge is a vital act, an assimilation of subject and object. The degree of activity regulates the degree of knowledge, of perfection; this goes on without a break until we reach the most perfect knowledge in God. Before we consider the knowableness of God, we must outline the factors involved in the activity of intellectual knowledge in man. "There is, therefore, a perfect and supreme grade of life, that of the intellect, for the intellect reflects upon itself and knows itself."{33} The human intellect though it can know itself, begins its knowledge with external things; it is inferior to the Angelic and Divine Intellects, but leads to a knowledge of them.
{1} De Veri., q. 2, a. 1, praeterea.
{2} Omnis cognitio fit per assimilationem cognoscentis et cogniti. C.G., l. 1., c. 65.
{3} Ad visionem tam sensibilem quam intellectualem duo requiruntur; Scilicet, virtus visiva, et unio rei visae cum visu. Non enim fit visio in actu, nisi per hoc quod res visa quodammodo est in vidente. Sum. Theol., I, q. 12, a. 2.
{4} Ratio cognitionis ex opposito se habet ad rationem materialitatis. De Veri., q. 2.
{5} This representative likeness is the same as image, for it implies some imitative reproduction of another thing, of the object to be known.
{6} The unity of action in knowledge is due to two co-principles. On the side of the subject, there is no complete act without the co-operation of the object, and the object is incapable of effecting a complete act without the work of the subject.
{7} Sic etiam intellectus, si haberet aliquam naturam determinatam, illa natura connaturalis sibi prohibet eum a cognitione aliarum naturarum. De Anima, 1. 3, lect. 7. The soul is quodammodo omnia.
{8} Though so recent an article as that of Dr. Lindsay, already referred to, has the following misconception of species: "Both Thomas and Duns Scotus held, each in his own way, to the doctrine of intelligible species, by which a copy of the object was supposed, in the process of knowledge, to arise and be seen by the soul." "In their doctrine of the "species intelligibiles" the two "Realists," Thomas and Duns Scotus, had alike followed, through some variations, the old Greek idea, that in the knowing process, by means of the cooperation of the soul and the external object, a copy of the latter arises, which is then apprehended and beheld by the soul." Windeband, A Hist. of Phil. p. 325. This thought is quoted by Ladd in a note of his Phil. of Knowledge, p. 53.
{9} Anima cognoscitiva sit in potentia tam ad similitudines quae sunt principia sentiendi, quam ad similitudines quae sunt principia intelligendi . . . Est in principio in potentia ad hujusmodi species omnes. Sum, Theol., I. q. 84, a 3.
{10} Species intelligibilis se habet ad intellectum sicut species sensibilis ad sensum. Ibid., 2. 85, a 2. There is a parallel between both species.
{11 }Id vero quod intelligitur est ipsa ratio rerum existentium extra animam. C. G., 1. 2, c. 75.
{12} Species intelligibilis non est id quod intelligitur, sed id quo intelligit intellectus. Sum. Theol., I. q. 85, a. 2.
{13} Quae quidem in nobis neque est ipsa res quae intelligitur neque est ipsa substantia intellectus, sed est quaedam similitudo concepta intellectu de re intellecta. C. G., 1. 4, c. 11.
{14} Omnis cognitio est secundum aliquam formam, quae est in cognoscente principium cognitionis. Forma autem hujusmodi potest considerari dupliciter: uno modo secundum esse, quod habet in cognoscente, alio modo secundum respectum quem habet ad rem, cujus est similitudo. Secundum quidem primum respectum facit cognoscentem aetu cognoscere; sed secundum secundum respectum determinat cognitionem ad aliquod cognoscibile determinatum. Et ideo modus cognoscendi rem aliquam est secundum conditionem cognoscentis, in quo forma recipitur secundum modum ejus. Non autem oportet ut res cognita sit quae est cognoscendi principium, habet esse in cognoscente. De Yen., q. 10, a. 4.
{15} De Veri., q. 2, a. 5, ad 7.
{16} Ad cognitionem non requiritur similitudo conformitatis in natura. sed similitudo repraesentationis tantum; sicut per statuam auream ducitur in cognitionem hominis. De Veri., q. 2, a. 5, ad 5.
{17} Ibid., ad 6.
{18} Ibid., a. 2. {19} Videtur autem in hoc Plato deviare a veritate, quia eum aestimaret omnem cognitionem per modum alicujus similitudinis esse eredidit, quod forma cogniti ex necessitate sit similitudinis esse modo, quo est in cognito. Sum. Theol., q. 84, a. 1.
{20} Omne quod recipitur in aliquo, est in eo per modum recipientis. De Causis is a work of Proclus the Platonist.
{21} This assimilation is a vital assimilation. In the cognitive life there is exactly the same process of assimilation as in the organic life, the process of nutrition; it is but a special and higher degree of assimilation.
{22} Secundum ordinem immaterialitatis in rebus, secundum hoc in eis natura cognitionis invenitur. De Veri., q. 2, a. 2.
{23} Quanto autem aliquid immaterialius habet formam rei cognitae, tanto perfectius cognoscit. Sum. Theol., I., q. 84, a. 2.
{24} Quod autem potest cognoscere aliqua, oportet ut nihil eorum habeat in sua natura, quia illud quod inesset ei naturaliter, impediret cognitionem aliorum. Ibid., q. 75, a. 2.
{25} St. Thomas uses the phrase, non enim cognoscitur aliquid secundum quod in potentia est, sed secundum quod est in actu, very frequently. He uses this quality of actuality as a proof for the immateriality of the soul. "The species of material things as they are in themselves are not intelligible actu, because they are in matter. But as they are in the intellective human soul they are intelligible actu." Quodlibetum 3, a. 20.
{26} Quia Deus est in fine separationis a materia, cum ab omni potentialitate sit penitus immunis, relinquitur, quod ipse est maxime cognoscitivus et maxime cognoscibilis. De Veri., q. 2, a. 2.
{27} Sum. Theol., I, q. 87, a. 1, ad 3.
{28} De Veri., q. 13, a. 3.
{29} Ibid., q. 10, a. 9.
{30} Aliquis percipit se animam habere et vivere et esse, quod percipit se sentire et intelligere et alia hujusmodi vitae opera exercere. De Veri., q. 10, a. 8.
{31} Ibid., q. 10, a. 8, ad 1. St. Thomas appreciated the difficulty of arriving at a knowledge of the nature of the soul. "Each one experiences in himself that he has a soul and that the acts of the soul take place within him, but to know the nature of the soul is most difficult." De Veri., q. 10, a. 8 ad 8. The same applies to our knowledge of the nature of God.
{32} Unde mens nostra non potest se ipsam intelligere, ita quod se ipsam immediate apprehendat sed ex hoc quod apprehendit alia devenit in suam cognitionem . . . Ex hoc enim quod species qua intelligimus est immaterialis; alias esset individuata, et sic non duceret in cognitionem universalis. De Veri, q.10, a. 8.
{33} Est igitur supremus et perfectus gradus vitae, qui est secundum intellectum; nam intellectus in seipsum reflectitur, et seipsum intelligere potest. C.G., 1. 4, c. 11.