---
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name: humanities-philosophy
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description: >
  Philosophy — ethics, logic, epistemology, metaphysics, political philosophy,
  philosophy of mind, and major philosophical traditions. Activate for questions
  about philosophical concepts, ethical frameworks, logical reasoning, theories of
  knowledge, or major philosophers and their ideas.
  Sources: Project Gutenberg (public domain), MIT OCW 24.00, Stanford Encyclopedia.
---

# Philosophy

## Major branches

**Metaphysics:** What exists? Nature of reality, existence, time, space, causality, free will.
**Epistemology:** What is knowledge? How do we know what we know? Justified belief, truth, skepticism.
**Ethics/Moral philosophy:** What is right and wrong? How should we live? What has moral value?
**Logic:** Valid reasoning, formal inference, fallacies.
**Political philosophy:** Justice, rights, authority, liberty, equality.
**Philosophy of mind:** Consciousness, mental states, personal identity.
**Aesthetics:** Beauty, art, taste, judgment.

## Major ethical theories

### Consequentialism / Utilitarianism

Actions judged by their outcomes. Right action = maximizes well-being/happiness.
**Bentham:** Felicific calculus — sum pleasure, subtract pain. "Greatest happiness for greatest number."
**Mill:** Quality of pleasures matters, not just quantity. Higher and lower pleasures.
**Objections:** Demandingness. Allows monstrous outcomes if consequences justify. Calculation problem. Ignores individual rights.

### Deontology (Kant)

Actions judged by whether they follow moral duties/rules, regardless of outcomes.
**Categorical Imperative (Kant):**
Formulation 1 (Universalizability): Act only according to maxims you could will to be universal laws.
Formulation 2 (Humanity): Act so you treat humanity always as an end, never merely as a means.
**Objections:** Conflicts between duties. Rigidity in extreme cases. Ignores consequences.

### Virtue Ethics (Aristotle)

Focus on character rather than rules or consequences.
Right action = what a virtuous person would do.
Virtues: Courage (mean between cowardice and recklessness), Justice, Temperance, Wisdom, Honesty.
**Eudaimonia:** Flourishing/happiness through exercise of virtues. The good life.
**Objections:** How to identify the virtuous person? Cultural relativism of virtues.

### Care Ethics (Gilligan, Noddings)

Emphasizes relationships, context, caring. Developed as critique of abstract principle-based ethics.
Moral decisions embedded in particular relationships and contexts.

### Contractarianism (Hobbes, Rawls)

Moral and political rules derive from social contract.
**Hobbes:** Without social contract, life would be "solitary, poor, nasty, brutish, short." We agree to give up some freedom for security.
**Rawls (A Theory of Justice):** Veil of ignorance thought experiment. Choose principles of justice without knowing your position in society. Leads to: Equal basic liberties + fair equality of opportunity + difference principle (inequalities acceptable only if they benefit the least advantaged).

## Major epistemological positions

**Rationalism (Descartes, Leibniz, Spinoza):** Knowledge primarily through reason and innate ideas. "I think therefore I am" (Cogito ergo sum).
**Empiricism (Locke, Hume, Berkeley):** Knowledge primarily through sensory experience. Mind as tabula rasa (blank slate).
**Kantian synthesis:** Combines both. Sensory experience necessary but mind structures it through a priori categories (space, time, causality).
**Pragmatism (Peirce, James, Dewey):** Truth = what works. Beliefs are tools.

## Logic fundamentals

### Deductive arguments

**Valid:** If premises true, conclusion must be true (structure guarantees).
**Sound:** Valid + actually true premises → true conclusion.
Classic valid form (modus ponens): If P then Q. P. Therefore Q.
Modus tollens: If P then Q. Not Q. Therefore not P.
**Fallacies:**
Ad hominem: Attack the person, not the argument.
Straw man: Misrepresent then attack.
False dichotomy: Only two options when others exist.
Appeal to authority: Citing authority as proof.
Circular reasoning: Conclusion in premise.

### Inductive arguments

Premises make conclusion probable, not certain.
Strong: Evidence genuinely supports conclusion.
Weak: Evidence doesn't support.
Cogent: Strong + true premises.

## Key philosophers (brief)

**Plato:** Theory of Forms (ideal realities), Republic (justice and ideal state), Allegory of the Cave (illusion vs. reality), Socratic method.
**Aristotle:** Logic (syllogism), ethics (virtue), politics, scientific method basis, four causes.
**Descartes:** Methodological doubt, mind-body dualism, innate ideas.
**Hume:** Causation is habit, not logical necessity. Problem of induction. Is-ought gap.
**Kant:** Critique of Pure Reason (categories of understanding), categorical imperative, practical reason.
**Nietzsche:** Will to power, übermensch, eternal recurrence, "God is dead," master/slave morality.
**Wittgenstein:** Early: limits of language (Tractatus). Late: meaning as use (Philosophical Investigations).
**Sartre:** Existence precedes essence. Radical freedom and responsibility. Bad faith.
**Rawls:** Political liberalism, theory of justice, veil of ignorance.
**Singer:** Effective altruism, animal rights utilitarian argument, drowning child argument.

Sources: Project Gutenberg (free public domain classics), MIT OCW 24.00 Problems in Philosophy (CC-BY-NC-SA), Stanford Encyclopedia of Philosophy (free, plato.stanford.edu), Oxford Dictionary of Philosophy (principles)