Plato’s Arguments for Soul Immortality: An Analysis

Posted on Aug 14, 2025 in Philosophy and ethics

Plato’s Phaedo: First Argument for Soul Immortality

This argument posits that opposites arise from opposites.

Part I: Theory of Opposites (Contra Heraclitus)

  • Introduction 1: Opposites are produced from their contraries.
  • Introduction 2: Life and death are contraries.
  • Introduction 3: From life, death is produced.

Conclusion:

From death, life will occur.

Plato’s Phaedo: Second Argument, Theory of Reminiscence

This argument recalls the theory of recollection as presented in Plato’s Meno, including the proof from the passage of the slave.

New Formulation of the Reminiscence Argument:

Humans must possess knowledge of absolute rules and models. This implicit knowledge is evident in their comparisons and value judgments. In the absence of these absolutes in the sensible world, the soul must have encountered them in a state of pre-existence.

Critiques of the First and Second Arguments:

  1. Critique of the First Argument: The analogy drawn by Plato remains inconclusive. The first part of the argument is based on rules governing the physical world, while the second does not account for the distinct nature of the soul.
  2. Critique of the Second Argument: It assumes the existence of absolute realities (e.g., the Equal, the Beautiful, the Just) that are perceived by the soul and then forgotten before joining the body. These forgotten absolutes supposedly allow us to make comparisons and judgments about the similarity of sentient beings or their involvement with these Forms. Plato does not question, not for a single moment, the possibility of attaining absolute knowledge—universal and necessary—from a reality that necessarily has to be immutable. Otherwise, one would have to recognize that these universal concepts or ideas are formed by the “abstraction” of perceived similarities between different sentient beings or their various actions. But then human knowledge would be particular, not universal; factual, not necessary.

Plato’s Phaedo: Third Argument, Soul as Life-Principle

Starting Point:

The existence of the Good, the Beautiful, the Large-in-itself, and other such Forms.

Development:

  • Opposites are mutually exclusive.
  • Things that essentially embody an opposite are also mutually exclusive.
  • The soul is the principle of life for bodies.
  • When death, instead of life, approaches, the soul cannot admit it.

Critiques of the Third Argument:

  1. The starting point (Theory of Forms) has already been widely criticized.
  2. It cannot definitively establish the essential character of a concrete being; for example, snow can be considered cold or hot depending on the context.
  3. Plato begs the question by considering the soul as the principle of life, which is then a priori considered immortal.
  4. It commits a fallacy by assuming that the soul, as the principle of life, inherently excludes its opposite: death. The conclusion should only be that the soul, while it exists, can only ever be living, not dead.

Plato’s Phaedrus: Soul Immortality as Self-Mover

The soul is the principle of self-motion. That which moves itself is eternal, having no beginning or end. If the principle of motion had an origin, then nothing would move. What has not occurred in infinite time is impossible to occur.

Critiques of the Phaedrus Argument:

  1. It has not been proven that the soul is the principle of self-movement.
  2. It contradicts the principle of causality: everything that moves is moved by another.