Acquinas and Metaphysics

 

Aquinas, explains the nature of metaphysics by distinguishing between two types of intellectual operations: speculative and practical. In speculative sciences, the intellect contemplates truth but does not apply it for practical purposes, leading to two distinct classes of science: speculative science and practical science.

The subject-matter of speculative sciences is that which can be understood to some extent. Aquinas believes that understanding something is dependent on its separation from matter and motion. This leads to three divisions of speculative objects: those dependent on matter and motion both for their being and understanding; those dependent on matter and motion for their being but not for their being understood; and those that depend on matter and motion neither for their being nor for their being understood.

Physical science considers these objects, while mathematics considers them but not for their being; and metaphysics or theology deals with those that depend on matter and motion neither for their being nor for their being. Aquinassees this division of the speculative sciences as exhaustive, as there could be no fourth speculative science since the subject-matter of such a science would have to be those things that depend on matter and motion for their being understood but not for their being.

Aquinas' metaphysics focuses on the third class of speculative objects, which includes things that depend on matter and motion. These objects are called positively immaterial, while neutrally immaterial are those that do not depend on matter and motion but can be found there. The neutrally immaterial can apply to both material and immaterial things.

Aquinas argues that unaided human reason cannot directly know the positively immaterial, as they outstrip human intellect's capacity to know. However, direct knowledge of the positively immaterial requires revelation. Metaphysics is a purely rational science, not dependent on revelations, and is a study of the neutrally immaterial aspects of things.

The proper subject-matter of metaphysics is ens commune (common being), which is the common aspects of being without which a thing could not be. Metaphysics primarily investigates the nature of essence and existence, which are generally applicable to all beings. After investigating essence and existence, the metaphysician must investigate the composition of substance and accident, and matter and form. The format of Thomistic metaphysics takes a dyadic structure of descending generality, focusing on essence and existence, substance and accident, and matter and form.

Aquinas's concept of essence is the definable nature of a thing that exists, signified by its definition. In finite entities, essence is that which has existence but is not existence. This is a fundamental metaphysical teaching that essence and existence are distinct in finite entities. Thomas's most famous and controversial instance is in De Ente et Essentia [On Being and Essence] Chapter Four, where he argues for a distinction between a thing's essence and its existence.

Aquinas takes the notion of universal hylemorphism as absurd, as it contradicts common philosophers' beliefs and contradicts the potency of immaterial substances. Instead, Aquinas argues that immaterial substances are composed of essence and existence, and it is the essence of the thing that accounts for the potentiality of creatures and distinguishes them from God.

Acquinas's argumentation for the distinction between essence and existence unfolds on three stages, with some commentators arguing that he intended and established the real distinction therein. Some argue that it is merely a logical distinction, while others focus on the distinction between the act of understanding a thing's essence and the act of knowing its existence.

Aquinas argues that a being whose essence is its existence would be unique and exist in a single absolute reality. This is evident from the way things can be multiplied, which can be in three ways: as a genus multiplied into its species, as a species multiplied into its individuals through being composed with matter, or as a thing is absolute and shared in by many particular things. Aquinasargues that a being whose essence is its existence cannot be multiplied in either of these ways, as it would not be subsistent but would be subsistent if it exists in virtue of what it is.

John Wippel argues that this is the decisive stage in establishing that essence and existence are really distinct. He argues that there cannot be more than one being whose essence is its existence, so there could not be many such beings in reality. Joseph Owens, on the other hand, argues that we cannot establish the real distinction until we have established that there is something whose essence is its existence. He argues that Aquinasestablishes the real distinction by comparing the existence of a being whose essence is its existence with the existence of finite entities, demonstrating that essence and existence are really distinct.

Aquinas’ metaphysical teachings on essence and existence are based on the idea that essence and existence are distinct concepts. He concludes that in immaterial substances, essence is related to existence as potency to act, which means that what receives existence stands in potency to the existence it receives. All things receive existence from the being whose essence is its existence, and the existence that any one finite thing possesses is an act of existence that actuates a corresponding potency: the essence.

Aquinas’ fundamental metaphysical teachings emphasize the importance of existence being efficiently caused in the essence/existence composite. He defines participation as taking part in something, which can happen in three ways: receiving universally relevant information, participating in accidents, or participating in its cause. Participation limits the nature of the thing in which it participates, as the participant will not possess the nature of the thing in which it participates in any total fashion but only in partial fashion.

Essences exist, but they do not exist essentially, participating in their acts of existence. Insofar as an essence participates in its act of existence, the essence limits that act of existence to the nature of the essence whose act it is. The act of existence is thus limited and individuated to the essence whose act it is, as the essence merely participates in and thereby limits the act of existence that it possesses.

Aquinas's metaphysical category of substance is primarily comprised of substances, which are essence/existence composites. Substances are basic entities that exist per se but are not identical with existence. The paradigm instances of substances are medium-sized objects like horses, cats, trees, and humans.

Accidents are incidental to substances and can only exist as part of some substance. In Aquinas's metaphysical framework, substances can be both material (cats, dogs, humans) and immaterial (angels). Material substances are composites of matter and form, and their parts cannot exist independently.

While parts of a substance are parts of a substance, they cannot themselves be substances. However, the elements out of which a substance is made can subsist beyond the dissolution of the substance. When the substance dissolves, the elements remain as independent substances in their own right.

In contemporary terms, atoms are substances in themselves before they form bodily substances, but when united in a certain form, they become substances in themselves. When the cat or dog or human perishes, its flesh and bones perish, but its atoms regain their substantial nature and remain as substances in themselves.

In conclusion, Aquinas's metaphysical framework focuses on the existence of substances and their relationships with their constituent parts. While parts of a substance cannot exist independently, they can be considered as substances in themselves when the substance decomposes.

Matter and form are fundamental concepts in physics, with matter being the substance from which a thing is made and form signified by its organization. A common example is a marble statue, where the marble is the material and the shape signifies the form. Form is the principle of potency in a thing, meaning it can be potentially an indefinite number of forms.

There are certain levels of matter/form composition, with the marble being the form and the marble being the matter. Prime matter, on the other hand, is the ultimate subject of form and indefinable. It is neither a substance nor any other categories of being, as it does not exist except as potency.

Matter can be considered in two senses: designated and undesignated. Designated matter is the type of matter to which one can point and make use, while undesignated matter is the abstracted notion of matter. Designated matter individuates some form, ensuring individuals of the same form (man).

Form can be substantial or accidental, with substantial form always informing prime matter and bringing a new substance into existence. Accidental form informs an already existing substance, modifying some substance. There can only be one substantial form of a thing, as any other form that may accrue to a thing is posterior to it and informs an already constituted substance.