Aristotle’s Cosmology

Aristotle’s Cosmology Dr. Paolo Biondi, Associate Professor Dept. of Philosophy, University of Sudbury

Order of Presentation • 1. The geocentric, spherical, and finite universe • 2. The division of the spherical cosmos into two distinct regions, the sublunary and superlunary • 3. The two corresponding kinds of fundamental matter, corruptible and incorruptible, each found within its respective region • 4. The natural motions and natural places of rest (for every entity) • 5. The soul as the source of life and principle of living beings • 6. The celestial bodies and spheres moved by ‘divine’ intellects • 7. The impossibility of any void • Concluding Remarks

1. The geocentric, spherical, and finite universe • Entire universe is a sphere of finite size • Earth sits immobile at the center • Celestial bodies orbit Earth: the moon, Mercury, Venus, the sun, Mars Jupiter, Saturn, the fixed stars (constellations of Greek zodiac) • Universe as a whole is eternal

2. Spherical cosmos divided into two distinct regions • The moon’s orbit as boundary line • 1) Sublunary region: below the moon’s sphere; includes Earth • 2) Superlunary region: above the moon’s sphere; includes the moon and all other celestial bodies

Main differences between the two regions: Sublunary Superlunary realm of eternal and everlasting being things exist in infinite time living beings are immortal • realm of generation and corruption • things exist in finite time • living beings are mortal

3. Two kinds of matter, each found within its respective region Corruptible and incorruptible matter

3.1 Corruptible matter in sublunary region • 4 simple natural bodies (elements): earth, water, air, fire • 4 basic sensible qualities in two opposed pairs: (i) the hot and the cold; (ii) the dry and the moist • The hot and the cold: active qualities • The dry and the moist: passive qualities • earth is cold and dry; water is cold and moist; air is hot and moist; fire is hot and dry • Prime matter: substrate and subject of 4 elements and 4 sensible qualities • Transformation among 4 natural bodies; hence corruptibility

3.2 Incorruptible matter in superlunary region • 1 simple natural body: aether • Has none of the 4 primary sensible qualities • Exempt from increase and decrease in size • Un-aging and unmodified • Not generated and indestructible, so incorruptible

4. The natural motions and natural places of rest (for every entity)

4.1 Nature • Nature is “a principle or source of being moved and of being at rest in that to which it belongs primarily, in virtue of itself and not accidentally” (Physics II.1, 192b21-23). • Nature contrasted with the artificial: internal source of motion versus external source of motion • Nature is not ‘Nature’ (i.e. the entire realm of natural things taken as one entity having a nature) • Nature usually signifies specific nature of each natural entity (like the species of a thing)

4.2 Natural motions • 1) In sublunary region: the four simple natural bodies have natural motion in straight line going in one direction • Direction determined relative to center of universe: upward motion is away from center; downward motion is toward center • Earth and water: downward motion is natural • Air and fire: upward motion is natural • Any other direction than natural one is unnatural, forced, violent • All other bodies composed of any of four elements: natural motion in straight line based on those of simple bodies composing them

4.2 Natural motions • 2) In superlunary region: the simple natural body aether has natural motion of going in a circle • Direction determined relative to center of universe: a revolution about the center, i.e. a line that maintains the same distance from the center by turning back upon itself • Circular motion is continuous, i.e. natural body moves though same space (place) infinitely through time

4.2 Natural motions • Linear and circular motion are the only two simple motions (possible for simple natural bodies) • Since circular motion is continuous, it is everlasting (infinite time) • Linear motion is not continuous; it is finite (has starting point and end point) and in finite time • Result is circular motion considered perfect in comparison to linear

4.3 Natural places of rest • 1) In sublunary region: natural places of rest for the primary simple natural bodies: • Earth: at the center of the universe • Water: against the earth and top of it • Air: above the water and surrounding Earth • Fire: above the air in uppermost section of sublunary region

4.3 Natural places of rest • 2) In superlunary region: natural place of rest for aether • No natural resting place, strictly speaking, but moves continuously through same circular orbit

5. Soul as the source of life and principle of living beings

5. Soul as the source of life etc. • Aristotle’s conception of soul is not Judeo-Christian view • Aristotle scholars still debating Aristotle’s conception of soul and its relationship to body • My position is that Aristotle’s conception of soul is not materialist and is not reductionist

5. Soul as the source of life etc. Non-living natural bodies Living natural bodies Have a soul Capable of manifesting life functions • Lack a soul • Not capable of manifesting life functions

5. Soul as the source of life etc. • Living being ‘composed’ of a soul and a body; form a unity, one entity possessing bodily integrity and wholeness • General definition of the soul, first formulation: the first level of actuality (actualization) of a natural body having life potentially in it • Second formulation of definition: the first level of actuality (actualization) of a natural organized body • Organized: natural body has organs, i.e. tools or instruments that enable organism to perform vital functions • Organs are functional, not material, parts of body • Actual performance of vital activities is second level of actuality of soul of organism

5. Soul as source of life • Three basic sets of capacities of the soul; thus three major kinds of living beings: • 1) Plants: capable of nutrition, growth (and decay), and reproduction – nutritive or reproductive soul • 2) Animals (non-human): capable of sensation; sensation gives rise to other capacities: appetite, imagination, memory, and moving from place to place (local motion) – sensitive soul • 3) Human beings: capable of reason or intellect or thought – rational or intellective soul • All living beings in sublunary region are a species of plants or a species of (non-human) animals or the human (animal) species

6. The celestial bodies and spheres moved by ‘divine’ intellects

6. The celestial bodies etc. • The living beings in the superlunary region include the sun, moon, (5 known) planets, and stars • Living beings composed of aether and intellective soul (or simply, the intellect) • Qualification: each celestial body is attached to its celestial sphere because body does not move in circle, its sphere does • Qualification: with the exception of the sphere containing all of the fixed stars (the outermost sphere), all celestial bodies actually have more than one sphere to move it • Set of spheres for one body nested within each other explains imperfectly circular orbit of body (as observed)

6. The celestial bodies etc. • There is a single celestial system of concentric spheres • Each sphere (not body) requires its own intellect to animate and move sphere in its continuous circular motion • This requirement based on Aristotle’s physics: a moving body cannot move itself, but requires something else acting as a mover

6. The ‘divine’ intellects • The celestial intellect is capable of causing motion and yet is itself unmoved (by another) • Celestial intellect is an “unmoved mover” and eternal and always active • Intellect’s activity is “an activity of thinking of/on thinking” • Intellect is an object of thought and/or an object of desire; as such, it moves with final causality, i.e. acting as a good that is desired and as an end that is sought (by celestial sphere) • Intellect moves by being loved (by celestial sphere moved by it)

6. The ‘divine’ intellects • Intellect’s activity is life: “for the actuality of thought is life, and God is that actuality. In fact, God’s self-dependent actuality is life most good and eternal; therefore, God is a living being, eternal, most good, so that life and duration continuous and eternal belong to God. For this is God” • Intellect is not natural, i.e. it is a supernatural entity • This entity is the principle upon which “the heavens and [the world of] nature” depend • There are as many intellects as there are spheres

7. The impossibility of any void • The void: an empty interval in which there is no sensible body; or a place with nothing in it • There is no void ‘outside’ or beyond’ universe; there is literally nothing ‘there’ (there is no there, really) • The whole universe contains the entirety of matter • The universe is a plenum, i.e. completely ‘full’ of matter; no void, ‘empty’ spaces or gaps, within matter • [prime] matter is a single matter for the natural contraries; and matter is not separable from the contraries; and a single matter may serve for all of the sensible qualities; and that which exists actually is produced from a potential existent

Concluding Remarks • Which concepts best explain the universe, e.g. finitude or the infinite, plenum or void, natural place of rest or infinite movement from inertia? • What is the nature of matter or the fundamental stuff of the universe? Is it possible to explain all phenomena existing in the universe in terms of this fundamental matter and its properties? Or would different levels of material complexity require different kinds of matter serving as their respective fundamental stuff or building blocks? • Is it possible to explain all phenomena in terms of matter alone? Or is something non-material like a soul required to explain certain phenomena that cannot be explained by matter and its properties (I am especially thinking about psychological and possibly, biological phenomena)?

Concluding Remarks • Does contemporary cosmology, a sub-discipline within physics, miss out on certain aspects of the universe, such as life, the phenomena of biology and psychology, and perhaps even the divine?

Questions? • Paolo Biondi contact: • pbiondi@usudbury.ca • Thank you!

Aristotle’s Cosmology