Key Concepts in Aristotle's Major Works

Why This Matters

Aristotle's works form the backbone of Western philosophical inquiry, and understanding them means grasping how he systematically approached everything—from what makes a good life to what makes an argument valid. You're not just learning about ancient texts here; you're learning the foundational frameworks for ethics, logic, metaphysics, and political theory that philosophers still engage with today. These concepts appear repeatedly in exam questions because they represent Aristotle's attempt to create a unified system of knowledge.

The key to mastering this material is recognizing how Aristotle's works interconnect. His ethics depends on his psychology (De Anima), his politics builds on his ethics, and his metaphysics underlies everything. Don't just memorize titles and definitions—know what type of inquiry each work represents and how its central concepts relate to his broader philosophical project.

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Works on Human Flourishing and Society

Aristotle believed philosophy should guide practical life. These works explore what it means to live well, both individually and collectively, grounding ethics in human nature and purpose.

Nicomachean Ethics

• Eudaimonia (flourishing)—the ultimate goal of human life, achieved through virtuous activity over a complete lifetime, not mere pleasure or wealth
• Virtue as the mean—moral virtues like courage exist as a balance between excess and deficiency, developed through habituation and practice
• Phronesis (practical wisdom)—the intellectual virtue that enables correct ethical judgment in particular situations; connects knowing the good to doing the good

Politics

• The state as natural—humans are political animals by nature; the polis exists to promote the good life, not just survival
• Forms of government—analyzes monarchy, aristocracy, and polity alongside their corrupted forms (tyranny, oligarchy, democracy)
• Ethics and politics intertwined—a good society produces virtuous citizens; individual flourishing requires a well-ordered community

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Works on Being and Reality

Aristotle's theoretical philosophy asks the deepest questions: What exists? What is the nature of reality? These works establish the conceptual vocabulary that dominated philosophy for centuries.

Metaphysics

• Being qua being—investigates existence itself, asking what it means for anything to be, beyond particular sciences
• Substance and essence—substance is the primary category of being; essence (to ti ên einai) defines what something fundamentally is
• The four causes—material, formal, efficient, and final causes explain why anything exists or changes; the final cause (telos) reveals purpose

Physics

• Nature and change—examines the principles governing motion and transformation in the natural world
• Potentiality and actuality—things move from potential states to actual states; this framework explains all natural change
• The unmoved mover—a necessary first cause of all motion that itself remains unchanging; connects physics to theology

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Works on Logic and Knowledge

Aristotle essentially invented formal logic. These works, later called the Organon ("instrument"), provide the tools for rigorous thinking and scientific demonstration.

Categories

• Ten categories of being—substance, quantity, quality, relation, place, time, position, state, action, and passion classify everything that can be said about reality
• Primary vs. secondary substance—individual things (this horse) are primary; species and genera (horse, animal) are secondary
• Foundation for logic—establishes the basic terms that propositions and arguments will employ

Prior Analytics

• The syllogism—a form of deductive argument with two premises and a conclusion; the first systematic account of valid inference
• Figures and moods—syllogisms are classified by the arrangement of terms; only certain combinations yield valid conclusions
• Formal logic established—reasoning can be analyzed by structure alone, independent of content

Posterior Analytics

• Scientific demonstration—true knowledge (episteme) comes from demonstrating conclusions from necessary first principles
• Knowledge vs. opinion—demonstration produces certainty; mere experience produces only familiarity with particulars
• Role of universals—science explains why things are as they are by appealing to universal truths, not just observing that they are

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Works on Soul and Life

For Aristotle, psychology (study of the soul) is part of natural philosophy. Understanding the soul means understanding what makes living things alive and capable of their characteristic activities.

On the Soul (De Anima)

• Soul as form of the body—the soul is not a separate substance but the organizing principle that makes a body alive; hylomorphism applied to living things
• Hierarchy of souls—nutritive (plants), sensitive (animals), and rational (humans) souls correspond to increasing capacities
• Nous (intellect)—the rational soul's capacity for abstract thought; controversially, Aristotle suggests it may be separable from the body

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Works on Art and Persuasion

These works apply Aristotle's systematic method to creative and communicative practices, revealing the principles underlying effective storytelling and speech.

Poetics

• Mimesis (imitation)—art imitates human action; tragedy specifically imitates serious, complete actions of a certain magnitude
• Plot as soul of tragedy—the arrangement of incidents matters most; a well-constructed plot produces the proper emotional effect
• Catharsis—tragedy purifies emotions of pity and fear through the audience's experience of the drama

Rhetoric

• Three modes of persuasion—ethos (speaker's credibility), pathos (audience's emotions), and logos (logical argument) work together in effective speech
• Rhetoric as counterpart to dialectic—both deal with probable matters where certainty is impossible; rhetoric applies to public persuasion
• Connection to ethics—persuasion should serve truth and justice; rhetoric is a tool that can be used well or badly

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Quick Reference Table

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Self-Check Questions

1. Which two works both address human flourishing but from different perspectives (individual vs. social)? What connects them?

2. If an exam question asks about Aristotle's theory of causation, which work provides the fullest account, and what are the four causes?

3. Compare and contrast Prior Analytics and Posterior Analytics—what is the key difference between valid reasoning and scientific demonstration?

4. How does Aristotle's concept of the soul in De Anima relate to his broader metaphysical framework of form and matter?

5. An FRQ asks you to explain how Aristotle's practical philosophy differs from his theoretical philosophy. Which works would you draw from for each category, and what distinguishes them?