Philosophical roots

Plato vs Aritstotle

Plato – The immortal soul and knowledge as reminiscence: 

Dualism: immortal soul, body as a prison.

Knowledge = reminiscence of what the soul already knew.

Psychology focused on the rational soul.

Aristotle – The soul as the form of the body

Hylomorphism: matter + form.

Soul = the vital principle of the body.

Functions: vegetative, sensitive, and rational.

Differences between Plato & Aristotle

Aspect	Plato	Aristotle
Conception of the soul	The soul is immortal and exists prior to the body.	The soul is the form of the body, an inseparable vital principle.
Soul-Body relationship	Dualism: The body is the soul’s “prison”	Substantial unity: soul and body from a single being.
Knowledge	Knowledge = recollection/reminiscence of what the soul knew before birth	Knowledge = the result of experience and reasoning in the world.
Faculties of the soul	Rational soul (superior), spirited (irascible), and appetitive (concupiscible)	Vegetative, sensitive, and rational souls.
Psychology	Metaphysical approach, focused on the immaterial.	Biological approach, focused on vital functions.

Plato

Plato saw the soul as an immortal, separate entity, with knowledge coming from innate ideas.

Aristotle

Aristotle viewed the soul as the life principle of the body, with knowledge arising from experience.

Soul and truth

Topic	Plato	Aristotle
Soul	Immaterial, eternal	Principle of life
Soul–body relationship	Soul separate from body	Soul inseparable from body
Knowledge	Innate knowledge; recollection of ideas	Knowledge from experience
Source of truth	World of Ideas	Natural world
Psychology	Study of the immortal soul	Study of living beings
View of humans	Soul temporarily trapped in body	Soul gives form to body

Saint Augustine – Interiority and memory

Synthesis of Plato and Christianity.

Interiority: the path toward God.

Memory = the place (or location) of truth and the divine.

Thomas Aquinas – Rational Soul and Form of the Body

Influence of Aristotle + Christianity.

Rational soul as a spiritual principle.

Faculties: vegetative, sensitive, rational.

Saint Augustine vs Thomas Aquinas

Aspect	Saint Augustine	Thomas Aquinas
Influences	Plato and early Christianity	Aristotle and medieval Scholasticism
Conception of the soul	Immortal soul created by God, oriented towards the divine truth.	Rational soul as the form of the body, a vital and spiritual principle.
Soul-body relationship	Moderate dualism: the soul dominates the body and transcends it.	Substantial unit: soul and body from a single human being.
Knowledge	Inferiority: knowing God through introspection and memory	Knowledge through the senses and reason, illuminated by faith.
Psychology	Emphasis on inner life and memory as the “space of God”	Emphasis on the faculties of the soul (vegetative, sensitive, rational) and their harmony.

Descartes – Mind-Body Dualism

Cogito ergo sum. (“I think, therefore I am”) 

Dualism: res cogitans vs. res extensa.

Believed that the mind and the body interact in the pineal gland

Descartes: Knowledge is grounded in reason and innate ideas.

Locke – Empiricism and the Tabula Rasa

Rejects innate ideas.

Mind at birth = blank slate.

Knowledge through sensation and reflection.

Locke: The mind is a blank slate shaped by experience.

Hume – Association of Ideas

Knowledge = perceptions (impressions + ideas).

Principles: similarity, contiguity, causality.

Psychology as a network of associations.

Hume: All knowledge comes from experience, and certainty is an illusion.

Kant – Limits and possibilities of psychology

Psychology cannot be an empirical science like physics.

It can be descriptive and systematic.

It delineates the conditions of knowledge.

Critical Voices – Hobbes and Spinoza

Hobbes: materialism, thought as the movement of matter.

• Spinoza: monism, mind and body = attributes of substance.

• Naturalistic and deterministic points of view.

Rationalism vs Empiricism

Rationalism → knowledge comes from reason

Empiricism → knowledge comes from experience

Descartes, Locke, and Hume

Topic	Descartes	Locke	Hume
Tradition	Rationalism	Empiricism	Empiricism (radical)
Source of knowledge	Reason	Experience	Experience only
Innate ideas	Yes	No	No
Mind at birth	Structured	Blank slate	Bundle of perceptions
Certainty	Possible	Limited	Impossible
Psychology Impact	Mind-first Mind-body problem	Learning-based Psychology as the study of experience and learning	Habit-based Learning through associations

Kant (Critique) to Descartes, Locke, and Hume

Knowledge arises from the synthesis between experience and a priori categories.

Not innate, but rather transcendental structures of the mind.

Critique: to delimit what we can know and under what conditions.

The mind organises experience with categories (space, time, causality).

Psychology as a discipline with epistemological limits.

Timeframe

4th c. BC

• Plato → Immortal soul; knowledge as recollection

• Aristotle → Soul as form of the body; functions
  
  4th c. AD

• Saint Augustine → Interiority; memory
  
  13th c.

• Thomas Aquinas → Synthesis of Aristotle & Christianity
  
  17th c.

• Descartes → Mind–body dualism

• Hobbes → Materialism

• Spinoza → Monism

• Locke → Tabula rasa (blank slate)
  18th c.

• Hume → Association of ideas
  Kant → Transcendental conditions of knowledge

Rationalism (authors & impact)

Authors & ideas

• Plato → Innate ideas; immortal soul
  

• Augustine → Interiority; memory
  

• Aquinas → Rational soul; faculties
  

• Descartes → Mind–body dualism; innate ideas
  
  Impact

• Reason over senses
  

• Introspection
  

• Mind–body problem

Empiricism (authors & impact)

Authors & ideas

• Locke → Tabula rasa; experience
  

• Hume → Perceptions; association
  

Impact

• Learning psychology

• Associationism

• Precursor to behaviourism