The discourse on the relationship between mind and matter and between human being and nature has been a pervasive theme throughout the history of Western philosophy. The philosophical views of Thomas Aquinas and Rene Descartes represent diametrically opposed aspects of this problem.
From Aristotle, Aquinas derived the concept of matter, not as an inert subject but having the potential to attain form. Aquinas does recognize the distinction between form and matter and stated that all physical creations have these two aspects. However, matter is not something separate and distinct but has the potentiality for actualization. In his commentary on Aristotle's De Anima he stated that, "Matter is that which is not as such a 'particular thing,' but is in mere potency to become a 'particular thing. " (K. Foster et al. 215)
In order to understand the often complex issue of Aquinas and the relationship between humanity and nature and the inclination towards the "good," one has to unravel the relationship between form and matter in Aquinas' philosophy. Speaking simplistically, Aquinas sees life and existence holistically and all living entities as interrelated according to certain foundational principles. This relates to his doctrine of form and matter, in which there is a conceptual connectivity between form and matter that suggests that all matter, including human, vegetative and animal are interconnected. This conceptual analysis is in direct contrast to the philosophy of Descartes who saw a severe and radical division between the various types of matter and between mind and body. In Cartesian philosophy the emphasis is on the separation of living forms and the division between different aspects of creation; whereas for Aquinas the emphasis is on interaction and interpenetration of the various elements within human beings and between man and nature.
While Aquinas was influenced by the works of Aristotle he deviated from these views to a certain extent when it came to the relationship between the soul and the body. Aristotle states a central thesis that informed the thoughts of Aquinas that "people are not two things - mind and body - but a complex that unites both the mental and the physical." (Burrell D.B.) For both Aquinas and Aristotle people are complex entities of form and matter or "ensouled bodies." (ibid)
One way to think of the relationship between form and matter is to see it conceptually in terms of potentiality and actuality; where matter is the potential which is actualized through form. The Scholastic concepts that Aquinas uses are intricate and complex. However, in essence Aquinas continually returns to the fact that the higher manifestations of human existence, such as the soul, are co-existent with and even in some cases dependent on the body and the senses. For Aquinas form cannot be thought of without matter and vice versa. The soul is essentially the form, in the sense of a shaping life force, of matter.
Aquinas' position is this. The human soul is able to exercise some activities which transcend the power of matter, and this shows that the soul itself is not material. And that which is not material does not depend intrinsically on the body for its existence. At the same time the soul is naturally the form of the human body, and it is natural for it to gain its knowledge in dependence on sense-experience.
This means that there is interdependence between form and matter. But this does not exclude the possibility of form being in some cases independent of matter.
The understanding of form and matter depends on the concepts of substance and accident in Aquinas. For purposes of this discussion substance refers to the forms and accidents are the shapes and attributes that matter assumes as predicates of these substances. Similarly, substance is the foundational element of being -- what something is -- while accident refers to the shapes and manifestations of that substance. These concepts are of Aristotelian origin and are expressed as follows: "Accidentis esse est inesse" and "Accidens non-est ens sed entis." The former quotation means "For an accident to be is of" and the latter translates as "An accident is not what is but is of what is." (Kenny A. 36) In other words, any predicate or "accident " must be an accident of something. For Aquinas, God created substances and not accidents. (ibid) A more detailed explication of these concepts is however outside the range of this paper. They illuminate the essential point being made; namely that form and matter are inextricably interwoven and that all of nature and humanity are linked through the way form shapes and interacts with matter. The Prime Substance for Aquinas does not change as such. "For a change of shape is an accidental change. Not a substantial change ... One way of explaining the concept of matter is to say that matter is what is common to the two termini of a substantial change. (Kenny A. 39) The idea of potentiality and actuality linking all existent things is expressed further in a passage from Aquinas.
In every change there must be a subject to change which is first in potentiality and then in actuality ... The forms of that into which something is turned begins to exist afresh in the matter of that which is turned into it ... If food is turned into a previously non-existent human being, then a form of the human being begins to exist in the matter of the food. (Summa Theologiae 111) (Kenny A. 39)
As is evident in the above extract, the concepts of form and matter have implications for the meaning of being human. As Copleston states,
In other words, the highest activities of the soul, and so the soul itself, are intrinsically independent of the body, in the sense that they can be exercised in the state of separation from the body; but at the same time they are extrinsically dependent on the body, in the sense that while the soul is united with the body it is dependent for its natural knowledge on sense-experience. (Copleston 162 )
For Aquinas the soul is the "form" or the Aristotelian 'entelecheia' of the body.
The above short overview in turn relates to the ethical and religious dimension of his thought, which refers to the purpose of all life. From the holistic concept of the interrelationship between all things it becomes evident that the central trajectory for all life is towards the realization of the highest good; which is the greatest potential. The idea of the good is related to the concept of form and substance in that it is a continuum which is motivated by the drive towards the understanding of God. " ... all things exist for the sake of God; God is their end or goal." (Kenny A. 11)
The philosophy of form and matter implies that the movement towards the good is intrinsically part of the process of life itself. For Aquinas this refers to "Intelligent and non-intelligent creatures alike, in so far as they develop in accordance with their natures, mirror divine goodness." (ibid) In this same sense human happiness lies not in success or moral virtue but in the knowledge of God. (ibid) All mutability is directed towards the revelation of God and the good.
The concepts discussed above differ radically for the view propounded by Descartes. The idea of substance generated from a union of form and matter differs fundamentally from Cartesian thought. In summary, Cartesian duality views the human being as composed of two separate substances; namely the soul or mind and the physical body. The essence or central element of the human is the mind or intellect and the body which has no real interaction or affect on this essence. This is the opposite of the view proposed by Aquinas.
Descartes states: "For in my opinion nothing without which a thing can still exist is comprised in its essence, and although mind belongs to the essence of man, to be united to a human body is in the proper sense no part of the essence of mind." (Anscombe E. And Geach P.)
Descartes' entire project in the Meditations on First Philosophy was "to argue that we have a clear and distinct idea of both matter and mind and that the two types of entities are utterly different." (Moreland J. And Wallace S.)
In attempting to explain the origins of this modern and very different view, one has to bear in mind the mileau in which Descartes developed his thoughts. Descartes asked himself the question - what could be known with certainty and through a method that was without any illusion? The strict method that he used was to exercise extreme skepticism about the world and to reduce all sensory and intellectual data so that only that which could be absolutely proven or known with certainty would be accepted. One must bear in mind that Descartes was writing at the beginning of the Enlightenment, at the inception of the emphasis on…