From Plato through Aristotle to Aquinas

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Question: Following on from our previous discussion, in what sense was Aristotle a follower of Plato?

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GPT5.1:

Aristotle was Plato’s man only in the way a bright apprentice is obliged, at least for a time, to nod respectfully at the master’s altar while quietly sharpening his own tools.

Three senses matter.

1. Institutionally.
He spent twenty years in the Academy. He absorbed its habits of mind: ruthless dialectic, the belief that philosophy is a serious craft, not a dilettante’s pastime. The Platonic project — reason as the spine of civilisation — became his own inheritance.

2. Methodologically.
Plato taught him the trick. Start with appearances, ask what they presuppose, follow the argument until you reach something that cannot be otherwise. Aristotle keeps the whole apparatus: definition, form, teleology, essence. Without the Platonic hunt for universals, Aristotle’s conceptual machinery would be empty.

3. Aspirationally.
Both men believed the world is intelligible in its deep structure. The quarrel was never over whether Forms exist but how they exist. Plato externalises them; Aristotle pulls them down into the world, gives them flesh, and declares the experiment complete. It is rebellion, yes, but rebellion within the family.

So Aristotle follows Plato in the way the Reformation “followed” the medieval Church — by overturning half the furniture while trying to keep the building standing. The lineage is unmistakable; the rupture is equally so.

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Question: In more detail, how did the forms become Aristotelian? Would that be substance and essence?

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GPT5.1:

Plato’s Forms descend from their chilly metaphysical Olympus and become Aristotelian by a simple but revolutionary manoeuvre: Aristotle refuses to let universals float free. He drags them bodily into the world, anchors them in things, and calls the result ousia — substance — with essence (to ti ēn einai) as its inner grammar.

Here’s the anatomy of that shift.

1. Plato: the exile of the real.
For Plato, the Form of Horse is not in the horse. It exists in a separate, purified register of being. Particular horses are only dim, defective instantiations. The world is a shadow-play; the real hangs elsewhere.

2. Aristotle’s rebellion: bring the universal home.
Aristotle snaps that tether. Whatever “horseness” is, it had better explain this horse, the sweating, snorting animal before us. Forms cannot live in exile. They must be immanent. If a universal has explanatory power, it must inhabit the world it organises.

3. Substance: the form-and-matter marriage.
Aristotle therefore re-engineers the basic unit of reality. A substance is form + matter:

• matter gives the stuff,

• form gives the organisation, the function, the identity.
  The horse is not a bad imitation of a heavenly Form; it is precisely a composite in which the form (the organising principle of horseness) is realised in the flesh.

4. Essence: the distilled form.
Essence is just form viewed through a conceptual microscope: that without which the thing wouldn’t be what it is. It’s the explanatory core. When Aristotle asks, “What is it to be a horse?” the answer is its essence — a determinate form lodged in matter, not some transcendent blueprint.

5. The metaphysical stakes.
Aristotle’s move solves several Platonic headaches at a stroke:

• it abolishes the need for a separate realm;

• it ends the “Third Man” regress;

• it restores causality to nature instead of shipping it off to heaven.

In effect, Plato gave Aristotle the idea of form, but Aristotle handed it a passport, naturalised it, and made it work for a living in the physical world. The Form becomes essence; the ideal entity becomes the structuring principle of a concrete thing; metaphysics stops being theology and becomes biology with a brain.

So yes — the Platonic Forms survive in Aristotle, but only after being domesticated, house-trained, and put to empirical use. They shed their transcendence and become the intelligible architecture of substances.

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Question: If no other realm, then no immortal soul?

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GPT5.1:

Aristotle leaves you with a soul that is embarrassingly local. If Plato built a celestial embassy for the psyche, Aristotle burns it down and forces the soul to take out a sensible tenancy agreement in the body.

The details matter.

1. Aristotle’s soul is not a ghost in the machine.
It is the form of a living body — the organising principle, the way the parts hang together as a functional unity. If you take away the body, most of what we call “soul” simply cannot stand on its own. Sight needs an eye; digestion needs a stomach; imagination needs a nervous system. The standard faculties die with the organism.

2. The notorious exception: the “active intellect”.
Aristotle hints — maddeningly and cryptically — that one sliver of the psyche, nous poiētikos, might be “separate, impassible, unmixed”. Mediaeval readers seized on this as a passport to immortality. Modern scholars mostly think Aristotle was talking about a universal intellectual function, not your personal consciousness hitching a ride into eternity.

In short: the individual human soul, as Aristotle conceives it, is not built for post-mortem travel. Its job is to animate this body; without the body, it collapses like a blueprint with no building to specify.

3. Why? Because he abolished the upstairs metaphysics.
If Forms live in the world, not in a transcendent realm, then the soul — as the form of a body — has nowhere metaphysically “up there” to go. The system offers no loft conversion for survival beyond death.

4. Christianity knew this and rewired him.
Aquinas has to perform theological surgery:

• He keeps Aristotle’s soul-as-form-of-the-body.

• But he adds the claim — alien to Aristotle — that the rational soul is individually subsistent and survives death.
  It works, but only by violating the Aristotelian rulebook.

So the blunt answer:
Aristotle gives you no personal immortality. His architecture doesn’t support it. If you want a soul that slips the leash and heads for a different realm, you’re back with Plato — or with the Christian synthesis that spliced Plato into Aristotle like a metaphysical chimera.

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