Hume

Central Problem

Hume confronts the ultimate epistemological challenge: can empiricism, when pursued with rigorous consistency, provide any foundation for knowledge at all? While Locke accepted the validity of knowledge within the limits of experience, and Berkeley preserved spiritual substance while denying material substance, Hume asks whether experience can justify even our most basic beliefs—in causation, the external world, and personal identity.

The problem has both theoretical and practical dimensions. Theoretically, if all our ideas derive from impressions (sensory experiences), what justifies our belief that the future will resemble the past, that causes necessarily produce effects, or that there exists a unified self persisting through time? Practically, given that our lives depend entirely on such beliefs, what is their actual foundation if not reason?

Hume’s investigation represents the culmination and crisis of modern empiricism. By rigorously applying the principle that every legitimate idea must trace back to a corresponding impression, he exposes the lack of rational foundation for beliefs that humans cannot help holding. This creates a profound tension between philosophical skepticism and natural belief.

Main Thesis

Hume’s central thesis is that human knowledge, when rigorously examined, proves to be founded not on reason but on habit, custom, and natural instinct. The necessity we attribute to causal connections is merely subjective—a product of psychological habit rather than objective rational insight. This leads to a “mitigated skepticism” that limits knowledge to relations of ideas (mathematics) and matters of fact (probable empirical generalizations).

Impressions and Ideas: All mental contents (“perceptions”) divide into impressions (vivid, forceful sensations, passions, emotions) and ideas (faint copies of impressions in memory and imagination). Every legitimate idea must derive from a corresponding impression—this is Hume’s fundamental principle and criterion for evaluating concepts.

Relations of Ideas vs. Matters of Fact: Hume distinguishes:

• Relations of ideas: Propositions true by definition, discoverable by pure thought, whose denial is contradictory (mathematics, logic). These are certain but tell us nothing about existence.
• Matters of fact: Propositions about existence, based on experience, whose denial is always conceivable. These tell us about the world but lack certainty.

Critique of Causation: The causal relation cannot be known a priori—we cannot deduce effects from causes by pure reason. Experience shows only constant conjunction (A regularly followed by B), never necessary connection. The “necessity” we feel is merely subjective—a product of habit. After repeatedly observing A followed by B, we form the expectation that B will follow A, but this expectation has no rational justification.

The Role of Habit: Habit (custom) is the “great guide of human life.” It produces in us the disposition to expect the future to resemble the past, to believe in causal connections, to act as if our beliefs were certain. Habit explains why we believe, but cannot justify our beliefs.

Belief in External World and Personal Identity: We have no impression of “substance” underlying our perceptions, nor of a unified, persisting “self.” The mind is merely “a bundle of perceptions” succeeding one another. Yet we naturally believe in external objects and personal identity—beliefs produced by imagination and habit, not reason.

Moral Sentiment: Morality is founded on sentiment, not reason. Reason alone cannot motivate action—only passion can. Moral judgments express feelings of approval or disapproval based on the perceived utility of actions for human happiness. The “moral sense” is grounded in natural sympathy with others.

Historical Context

Hume (1711-1776) lived during the Scottish Enlightenment, a remarkable period of intellectual flourishing in Edinburgh that produced major figures in philosophy, economics, and science. Scotland, though recently united with England (1707), developed its own distinctive intellectual culture, less ecclesiastical and more cosmopolitan than English thought.

Born in Edinburgh, Hume came to philosophy young, composing his Treatise of Human Nature (1739-40) before age 30 while living in France. The work’s initial failure (“It fell dead-born from the press”) led him to recast its ideas in more accessible form in the Enquiries (1748, 1751). His celebrity came through his Essays and History of England, making him the most famous British man of letters of his time.

The intellectual context included Newton’s triumph in natural philosophy, which inspired Hume’s ambition to become “the Newton of the moral sciences”—applying empirical, experimental method to human nature itself. Hume admired Newton’s achievement while questioning whether similar certainty was attainable for knowledge of human affairs.

Hume’s religious skepticism, expressed in Dialogues Concerning Natural Religion (published posthumously, 1779) and Natural History of Religion (1757), made him controversial. He was twice denied university positions on grounds of alleged atheism. Yet he was personally admired for his good humor, sociability, and moral character—demonstrating that philosophical skepticism need not undermine practical virtue.

Hume’s influence was decisive for Kant, who acknowledged that Hume “awakened me from my dogmatic slumber” and stimulated the critical philosophy that sought to overcome Humean skepticism.

Philosophical Lineage

flowchart TD
    Ockham --> Locke
    Locke --> Berkeley
    Berkeley --> Hume
    Newton --> Hume
    Locke --> Hume
    Hutcheson --> Hume
    Hume --> Kant
    Hume --> Bentham
    Hume --> Mill
    Hume --> Logical-Positivism
    Hume --> Naturalized-Epistemology

    class Ockham,Locke,Berkeley,Newton,Hume,Hutcheson,Kant,Bentham,Mill,Logical-Positivism,Naturalized-Epistemology internal-link;

Key Thinkers

Thinker	Dates	Movement	Main Work	Core Concept
Hume	1711-1776	British Empiricism	Treatise of Human Nature	Skepticism about causation, habit
Locke	1632-1704	British Empiricism	Essay Concerning Human Understanding	Ideas from experience
Berkeley	1685-1753	British Empiricism	Principles of Human Knowledge	Esse est percipi
Newton	1642-1727	Scientific Revolution	Principia Mathematica	Experimental method
Kant	1724-1804	German Idealism	Critique of Pure Reason	Transcendental idealism

Key Concepts

Concept	Definition	Related to
Impressions	Vivid, forceful perceptions: sensations, passions, emotions as originally experienced	Hume, Empiricism
Ideas	Faint copies or images of impressions in memory and thought	Hume, Epistemology
Relations of ideas	Propositions true by definition, certain but not about existence (mathematics, logic)	Hume, Logic
Matters of fact	Propositions about existence, based on experience, always uncertain	Hume, Epistemology
Constant conjunction	The observed regularity of one event following another; all we perceive of causation	Hume, Causation
Habit/Custom	The psychological disposition, produced by repetition, to expect future to resemble past	Hume, Psychology
Association of ideas	The natural tendency of mind to connect ideas by resemblance, contiguity, or causation	Hume, Psychology
Belief	A vivid idea associated with present impression; natural instinct, not rational judgment	Hume, Epistemology
Bundle theory	The self is nothing but a bundle of perceptions succeeding one another	Hume, Personal Identity
Moral sentiment	Feelings of approval/disapproval based on perceived utility; foundation of ethics	Hume, Ethics

Authors Comparison

Theme	Hume	Locke	Berkeley
Source of knowledge	Impressions only	Experience (sensation and reflection)	Ideas perceived by mind
Causation	Habit, no objective necessity	Real connection in nature	God’s regular action
External world	Belief without rational justification	Exists, known through ideas	Does not exist independently
Personal identity	Bundle of perceptions	Continuous consciousness	Spiritual substance
Substance	Unintelligible fiction	Unknown substratum	Spirit only
Abstract ideas	Particular ideas as signs	General ideas by abstraction	Particular ideas as signs
Role of reason	Limited to relations of ideas	Guide within experience	Instrument of religion
Moral foundation	Sentiment, sympathy	Rational demonstration	Divine command

Influences & Connections

• Predecessors: Hume ← influenced by ← Locke (empiricism), Berkeley (nominalism, critique of abstraction)
• Predecessors: Hume ← influenced by ← Newton (experimental method), Hutcheson (moral sense theory)
• Contemporaries: Hume ↔ dialogue with ↔ Smith (sympathy, economics), Rousseau (brief friendship/quarrel)
• Followers: Hume → influenced → Kant (critical philosophy), Bentham (utilitarianism)
• Followers: Hume → influenced → Mill (empiricism, utilitarianism), Logical Positivism (verification principle)
• Opposing views: Hume ← criticized by ← Reid (common sense philosophy), Kant (transcendental response)

Summary Formulas

• Hume: All ideas derive from impressions; causation is mere constant conjunction plus psychological habit; reason is the slave of the passions; the self is a bundle of perceptions; morality rests on sentiment and sympathy.
• Locke: Experience is the source and limit of knowledge; within those limits, reason can attain certainty about self, God, and present sensations.
• Berkeley: All that exists are minds and their ideas; God guarantees the order and continuity of our perceptions.
• Kant: Hume’s skepticism must be overcome by showing that the mind’s a priori categories make objective experience possible.

Timeline

Year	Event
1711	Hume born in Edinburgh, Scotland
1734-1737	Hume lives in France, composes Treatise of Human Nature
1739-1740	Hume publishes Treatise of Human Nature (unsuccessful)
1741-1742	Hume publishes Essays, Moral and Political (successful)
1748	Hume publishes Enquiry Concerning Human Understanding
1751	Hume publishes Enquiry Concerning the Principles of Morals
1752	Hume becomes librarian in Edinburgh; begins History of England
1757	Hume publishes Natural History of Religion
1763-1766	Hume serves as secretary to British embassy in Paris
1776	Hume dies in Edinburgh
1779	Hume’s Dialogues Concerning Natural Religion published posthumously

Notable Quotes

“When we run over libraries, persuaded of these principles, what havoc must we make? If we take in our hand any volume—of divinity or school metaphysics, for instance—let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames, for it can contain nothing but sophistry and illusion.” — Hume

“Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them.” — Hume

“The mind is a kind of theatre, where several perceptions successively make their appearance; pass, re-pass, glide away, and mingle in an infinite variety of postures and situations.” — Hume

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NOTE

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