Key Philosophical Concepts and Arguments

Posted on Feb 27, 2025 in Philosophy and ethics

Philosophy: Critical reasoning about ultimate questions.

Argument: A set of propositions consisting of premises and a conclusion.

Deduction: Arguments where the conclusion follows necessarily from the premises.

Induction: Arguments where the conclusion follows from the premises with some degree of probability.

Validity: When it is impossible for a deductive argument to have all true premises and a false conclusion.

Soundness: When a deductive argument is valid and all the premises are actually true.

Strength: When the conclusion is probable/likely relative to the premises in an inductive argument.

Reliability: When an inductive argument is strong and all the premises are actually true.

Modus Ponens: If A then B. A. Therefore, B.

Modus Tollens: If A then B. Not B. Therefore, not A.

Analogy: An argument that moves from one specific example to another, reasoning that because the two examples are alike in many ways, they are also alike in one further specific way.

Epistemology: The subfield of philosophy that concentrates on what we can know.

Metaphysics: The subfield of philosophy that concentrates on what is ultimately real.

Relativism: The view that truth and goodness are solely relative to a human individual or culture; that a person or a culture is the sole arbiter of what is true and right.

Asceticism: Abstention from all forms of self-indulgence; highly self-disciplined for the sake of achieving some single goal.

Metempsychosis: The process whereby eternal souls transmigrate from body to body.

Plato’s Republic: The Just Life vs. The Unjust Life

Republic 576b-580c: First Proof

  1. The tyrannical life is a miserable life.
  2. No miserable life can be a model of the good life.
  3. Therefore, the tyrannical life cannot be a model of the good life.
  1. The soul that rules itself like a philosopher king or queen is the best life.
  2. The best life should be accepted as the model of the good life.
  3. Therefore, the soul that rules itself like a philosopher king or queen should be accepted as the model of the good life.

Republic 580d-583b: Second Proof

  1. Whoever experiences the pleasures of all aspects of the soul is best suited to judge which way of life is best.
  2. The philosopher experiences the pleasures of all aspects of the soul.
  3. Therefore, the philosopher is best suited to judge which way of life is best.
  1. Whatever the philosopher uses as her tool for finding truth and supporting her experience is sufficient to tell us which life is best.
  2. Argument is what the philosopher uses as her tool for finding truth and supporting her experience.
  3. Therefore, argument is sufficient to tell us which life is best.

Republic 583b-588a: Third Proof

  1. Being filled with what is unchangeable is always better than being filled with what is changeable.
  2. The goods of the non-philosopher are changeable and never unchangeable.
  3. The goods of the philosopher are unchangeable and never changeable.
  4. Therefore, the goods of the philosopher are always better than the goods of the non-philosopher.
  1. If a person does not follow/pursue philosophical reasoning, then (s)he will not ultimately satisfy the other parts of the soul.
  2. Everyone should want to ultimately satisfy the entire soul.
  3. Therefore, a person should follow/pursue philosophical reasoning.
  1. The happiest life is the best life.
  2. The best life is the philosophical life.
  3. The philosophical life is the just life.
  4. Therefore, the happiest life is the just life.

Republic 611a: Proof for the Immortality of the Soul

  1. Anything that can be destroyed is destroyed by what is bad for it.
  2. The soul is not destroyed by what is bad for it.
  3. Therefore, the soul cannot be destroyed.

Republic 611b: Another Proof for the Immortality of the Soul

  1. Only what can be divided into spatial parts can be destroyed.
  2. Everything that can be divided into spatial parts is material.
  3. No soul is material.
  4. Therefore, no soul can be destroyed.

Aristocracy and Appetites

Aristocracy = rational, Timocracy = spirited, Oligarchy = necessary appetites, Democracy = Unnecessary appetites, Tyranny = Unlawful Unnecessary appetites