Impressions & Ideas
Relations & Reasoning
The Problem of Induction
Method, Knowledge & Human Nature
Bonus Round (Double Jeopardy!)
100

What is the distinction Hume made between impressions and ideas?

Hume distinguishes impressions and ideas based on their force and vivacity (or liveliness).

  • Impressions are the more forceful and lively perceptions that occur when we experience something directly through our senses or have immediate feelings and emotions. They include all our sensations, passions, and emotions as they first appear to the mind.
  • Ideas are the faint copies or images of impressions in thinking and reasoning. They are less forceful and vivid than impressions—they're what we have when we remember, imagine, or think about something that isn't immediately present to our senses.

For example, the difference between actually feeling the warmth of fire (impression) and merely thinking about or remembering that warmth (idea). The impression is vivid and forceful; the idea is a dimmer copy of that original experience.

100

What are the two types of "objects of human reason and enquiry" for Hume? Explain the nature of each.

Hume divides all objects of human reason into two categories:

  1. Relations of Ideas: These are propositions that concern the relations between our ideas or concepts themselves, discoverable by pure thought alone. They include mathematics, geometry, and logic.
    • Nature: These propositions are true by definition or by the relations between the concepts involved. Their denial would involve a contradiction.
    • Examples: "2 + 2 = 4," "All bachelors are unmarried," "The square of the hypotenuse equals the sum of the squares of the other two sides."
    • Certainty: We can be absolutely certain of relations of ideas through demonstration and intuition alone.
  2. Matters of Fact: These are propositions about what actually exists or occurs in the world—empirical claims about reality.
    • Nature: These propositions are based on experience and observation. Their denial does not involve a contradiction—the opposite is always conceivable.
    • Examples: "The sun will rise tomorrow," "Fire causes heat," "Caesar was assassinated."
    • Uncertainty: We cannot be absolutely certain of matters of fact through reason alone; they depend on experience.

This distinction is sometimes called "Hume's Fork" and becomes extremely important for his epistemology.

100

What is the problem of induction? Why does this problem make it impossible to have knowledge concerning any natural laws (if knowledge is true justified belief)?

The Problem of Induction is the problem of justifying inferences from observed cases to unobserved cases—or from past experience to future expectations.

The Problem:

We constantly reason inductively:

  • "The sun has risen every day in the past, so it will rise tomorrow"
  • "Every flame I've touched has been hot, so the next flame will be hot"
  • "All observed emeralds have been green, so the next emerald will be green"

But what justifies this kind of reasoning? Why should past experience be a reliable guide to the future?

The underlying assumption is the Uniformity of Nature principle: nature will continue to operate by the same laws; the future will resemble the past; unobserved cases will resemble observed cases.

But how can we justify this principle?

  1. Not by logic/relations of ideas: It's not a logical truth. There's no contradiction in imagining nature suddenly changing—bread nourishing us yesterday but poisoning us tomorrow.
  2. Not by experience/matters of fact: This would be circular reasoning. We'd be saying "induction has worked in the past, therefore it will work in the future"—but that's itself an inductive argument! We'd be using induction to justify induction.

Why this makes knowledge of natural laws impossible:

Natural laws (like "fire causes heat" or Newton's laws of motion) are generalizations based on observation. We observe some cases and inductively generalize to all cases.

But if induction cannot be rationally justified, then:

  • We have no rational justification for believing these laws hold in unobserved cases
  • We cannot rationally justify that they'll continue to hold in the future
  • Therefore, we cannot have justified beliefs about natural laws

Since knowledge requires justification (in the traditional definition: justified true belief), we cannot have knowledge of natural laws. At best, we have habits of expectation that happen to be useful but lack rational foundation.

100

In what sense is Hume an empirical psychologist? What is his scientific method?

Hume is an empirical psychologist in the sense that he studies the human mind using the methods of natural science, based on observation and experience rather than pure reason or speculation.

What Makes Him Empirical:

  1. Observation-based: Hume's method relies on careful observation of how the mind actually works—how ideas associate, how beliefs form, how people actually reason—rather than speculating about how the mind should work according to some rational ideal.
  2. Experience as foundation: Like other empirical sciences, Hume's psychology starts from experience. He observes mental phenomena (impressions, ideas, associations, emotions) just as a natural scientist observes physical phenomena.
  3. Generalizing from cases: He observes patterns in mental life and generalizes to form psychological laws, just as physicists observe patterns in nature and formulate physical laws.

His Scientific Method:

Hume explicitly models his approach on Newtonian physics:

  1. Phenomena identification: Identify the basic mental phenomena (impressions, ideas) through introspection and observation.
  2. Pattern discovery: Look for regular patterns and associations in mental life—how ideas connect, how beliefs form, how expectations arise.
  3. Laws formulation: Formulate simple, general principles that explain these patterns (like the three laws of association: resemblance, contiguity, cause and effect).
  4. Simplicity and unification: Seek the simplest principles that can explain the widest range of mental phenomena—just as Newton's gravity explained diverse physical phenomena with one principle.
  5. Descriptive, not prescriptive: Describe how the mind actually operates, not how it ought to operate according to rational norms.

The "Science of Man":

Hume saw himself as founding a new science—the science of human nature. Just as Newton had uncovered the laws governing physical nature, Hume aimed to uncover the laws governing human mental life. His empirical approach made psychology a scientific enterprise rather than speculative metaphysics, focusing on observable phenomena and their regular patterns rather than on abstract essences or rational principles.

200

According to Hume, what are the sources of our ideas? What were his arguments for this conclusion?

According to Hume, all ideas are ultimately derived from impressions. There is no other source for our ideas—every simple idea must correspond to a prior simple impression.

Hume's Arguments:

  1. The Correspondence Argument: Hume observes that all our simple ideas correspond to simple impressions, and all our simple impressions have corresponding ideas. This one-to-one correlation suggests a connection between them.
  2. The Priority Argument: Impressions always come first in time—we must have the impression before we can have the corresponding idea. We cannot form an idea of a color we've never seen, or a taste we've never experienced.
  3. The Missing Shade of Blue (Counterexample): Hume honestly considers a potential counterexample: Could someone who has seen all shades of blue except one particular shade imagine that missing shade by interpolation? Hume admits this might be possible but dismisses it as too singular and insignificant to overturn his general principle.
  4. Deficiency Argument: People who lack certain sensory capacities (like a blind person or deaf person) cannot form ideas of the corresponding sensations (colors or sounds). This shows that without the impression, the idea cannot arise.

Conclusion: Ideas are copies of impressions, and all meaningful concepts must ultimately trace back to sensory experience.

200

Which type of "objects of human reason" provides us with knowledge (rational justification), and why can't the other type provide such knowledge?

Only Relations of Ideas provide us with genuine knowledge in the strict sense—knowledge that is rationally justified with certainty.

Why Relations of Ideas provide knowledge:

  • They are knowable by reason alone through intuition and demonstration
  • They are certain and cannot be false
  • Their truth is guaranteed by the logical relations between the concepts involved
  • Denying them produces a contradiction

Why Matters of Fact cannot provide knowledge (in the strict sense):

Matters of fact depend on experience, and experience alone cannot provide rational justification:

  1. No Logical Necessity: The opposite of any matter of fact is always conceivable without contradiction. "The sun will not rise tomorrow" is perfectly conceivable, even if we've never experienced it.
  2. Dependence on Induction: All reasoning about matters of fact beyond immediate perception depends on causal reasoning, which in turn depends on inductive inference (reasoning from past experience to future cases).
  3. Induction Cannot Be Justified: Inductive reasoning assumes that the future will resemble the past (the Uniformity Principle), but this assumption itself is a matter of fact that cannot be proven without circular reasoning.

Therefore, while we inevitably and rightly believe many things about matters of fact, these beliefs cannot be rationally justified with certainty. They rest on custom and habit, not reason. This is Hume's radical skeptical conclusion: most of what we take ourselves to know about the world is not, strictly speaking, knowledge at all—at least not if knowledge requires rational justification.

200

Explain Hume's skeptical resolution to the problem of induction. Be sure to include a discussion of the role played by such notions as reason, instinct, custom, habit, and sentiment.

Hume's skeptical resolution accepts that induction cannot be rationally justified, but argues this doesn't matter for practical life. The resolution has two parts:

Part 1: The Skeptical Conclusion (What Reason Cannot Do)

  • Reason alone cannot justify our inductive inferences or causal reasoning
  • Reason cannot prove that nature is uniform or that the future will resemble the past
  • Therefore, our beliefs about matters of fact beyond immediate observation lack rational justification

Part 2: The Positive Solution (What Nature Does Instead)

Even though reason cannot justify induction, we inevitably make inductive inferences anyway. Why?

  1. Custom and Habit: Through repeated experience of constant conjunction (A followed by B, repeatedly), we develop a habit or custom of expecting B when we observe A. After touching many hot flames, we automatically expect the next flame to be hot. This is a psychological mechanism, not a rational inference.
  2. Natural Instinct: This habitual expectation is not something we choose or reason our way into—it's an instinctive part of human nature. Just as we instinctively pull our hand away from fire, we instinctively form expectations based on past experience. Nature has built this mechanism into us.
  3. Sentiment/Feeling: When we observe a cause, custom produces a feeling of expectation about the effect. This is a "determination of the mind" or sentiment, not a rational inference. We feel that the effect will follow; we don't reason it out.

Why This Is a "Skeptical" Resolution:

  • It's skeptical because it admits reason cannot justify our beliefs
  • But it resolves the problem by showing we don't need rational justification to continue believing and acting
  • Our inductive practices rest on non-rational psychological foundations

The Upshot:

We should abandon the pretense that our causal reasoning is rationally justified. Instead, we should recognize that:

  • Nature has equipped us with mechanisms (custom, habit, instinct) that produce reliable beliefs
  • These mechanisms work independently of reason
  • They're sufficient for practical life, science, and survival
  • Reason plays a much smaller role in human life than rationalists supposed

Hume thus replaces justification (a rational, normative notion) with explanation (a psychological, descriptive notion). He doesn't justify our inductive practices; he explains why we inevitably engage in them.

200

Why might Hume think that his theory of human nature will be believed by the reader?

This question has a delightfully ironic answer that shows Hume's self-awareness about his own philosophy.

The Answer:

Hume can be confident that readers will come to believe his theory because of the very psychological mechanisms his theory describes!

The Mechanisms:

  1. Constant Conjunction and Custom: As readers repeatedly encounter Hume's explanations alongside their own mental experiences, they observe a constant conjunction between his descriptions and their introspections. This repeated association creates a custom or habit—they come to expect that Hume's principles will continue to explain their mental life accurately.
  2. Natural Instinct: The mechanisms Hume describes (association by resemblance, contiguity, and cause-effect) are operating in the reader's mind right now as they read and evaluate his theory. The theory appeals to our natural psychological processes.
  3. Explanatory Power: When Hume explains that we form expectations through custom rather than reason, readers recognize this pattern in their own experience. This recognition itself reinforces belief in the theory through the very mechanisms of habit and association Hume describes.
  4. Self-Evidence Through Introspection: Readers can observe in their own minds the phenomena Hume describes—they can notice how their ideas associate, how impressions differ from ideas in vivacity, how repeated experiences create expectations.

The Self-Referential Twist:

The reader's belief in Hume's theory is not based on rational proof (which would be impossible given his skepticism about induction). Instead, the reader believes the theory because:

  • It's repeatedly confirmed by introspection (constant conjunction)
  • This creates a habit of expecting the theory to be accurate (custom)
  • This habit produces a feeling of conviction (sentiment)

In other words, we believe Hume's theory through the very mechanisms the theory describes, not through rational demonstration. The theory is self-validating in a psychological (though not logical) sense.

The Irony:

Hume can thus be confident readers will believe him—not because he's provided rational justification, but because human nature is such that we inevitably form beliefs based on repeated experience and custom. We can't help but believe theories that repeatedly prove explanatorily useful, even if we can't rationally justify them.

This shows Hume's radical break with rationalism: he's not trying to convince readers through logical argument alone. He's relying on the natural, inevitable psychological processes that govern all human belief-formation.

200

What might Hume ultimately say to the persistent skeptic? What do you think of this reply?

Two-part response:

  1. Theoretical agreement: "You're right—reason can't justify our fundamental beliefs. Skepticism is theoretically irrefutable."
  2. Practical impossibility: "But you can't actually live as a skeptic. Nature forces you to believe in causation, external objects, and induction the moment you engage with ordinary life. Custom and habit override philosophical doubt."

His advice: Don't fight nature. Pursue philosophy in moderation as entertainment, not as a life guide. Skeptical doubts dissolve naturally through dinner with friends and ordinary activities.

Assessment: Psychologically astute and honest, but philosophically unsatisfying—Hume changes the subject from justification to psychology. It's wisdom if philosophy should describe human nature, evasion if it should provide rational justifications.

300

What are Hume's three laws of mental association? Explain each. In what sense does Hume take his project to be analogous to Newton's?

Hume identifies three principles by which ideas naturally connect with one another in the mind:

  1. Resemblance: Ideas that resemble each other tend to associate. For example, seeing a portrait of someone naturally leads our mind to think of the person themselves. Similar things remind us of each other.
  2. Contiguity (in time or place): Ideas of things that are near each other in space or time tend to associate. Thinking of one room in a house makes us think of adjacent rooms; mentioning an event makes us think of what happened right before or after it.
  3. Cause and Effect: Ideas of causes naturally lead to ideas of their effects and vice versa. Thinking of a wound makes us think of pain; thinking of fire makes us think of heat and smoke.

Analogy to Newton:

Hume explicitly models his project on Newton's physics. Just as Newton discovered the law of universal gravitation that explains the movements and attractions of physical bodies throughout the universe using a simple principle, Hume aims to discover the fundamental laws that govern the movements and associations of ideas in the mind.

Newton showed that diverse physical phenomena (falling apples, planetary orbits, tides) could be explained by one gravitational force. Similarly, Hume believes that the seemingly chaotic flow of thoughts can be explained by these three simple principles of association. Hume wants to be the "Newton of the mind"—reducing complex mental phenomena to a few fundamental psychological laws that operate with regularity.

300

Why, according to Hume, must all knowledge concerning matters of fact be grounded in the relation of cause and effect?

Hume argues that there are only two ways we can know matters of fact:

  1. Direct observation: What we immediately perceive through our senses right now
  2. Inference beyond observation: What we conclude about things we're not currently perceiving

For all matters of fact beyond immediate observation, we must rely on the relation of cause and effect.

Hume's Reasoning:

When we want to know about matters of fact that go beyond present perception—whether about the past, the future, or what exists elsewhere—we must make inferences. But on what basis can we make these inferences?

  • Not from relations of ideas: Logical and mathematical reasoning alone cannot tell us what actually exists or what will happen. From the idea of bread alone, I cannot deduce that it will nourish me.
  • Not from resemblance or contiguity alone: These relations of association explain how ideas connect in our minds, but they don't justify inferences about what actually exists in reality.
  • Only through cause and effect: When I see smoke, I infer fire (cause and effect). When I see footprints, I infer someone walked there (cause and effect). When I observe the sun rising every day, I predict it will rise tomorrow (cause and effect).

The Crucial Point:

All reasoning concerning matters of fact beyond immediate perception assumes causal connections. We observe one thing and infer something else about reality only when we believe the two are causally related. Without causal reasoning, we would be trapped in the immediate present moment, unable to draw any conclusions about anything we're not directly perceiving.

As Hume says, remove cause and effect, and "all commerce would cease, and conversation would be at an end, and action would be impossible." Our entire understanding of the world beyond immediate perception rests on causal inference.

300

How did the rat trap discussion in class illustrate Hume's skeptical solution to the problem of induction?

The rat trap example vividly illustrates the difference between human reasoning and the natural, instinctive basis of inductive inference.

The Scenario:

Imagine a rat that gets caught in a trap. If the rat somehow escapes or is released, what happens when it encounters similar traps in the future?

The Rat's Response:

The rat will avoid similar traps. After one experience of trap → pain/danger, the rat develops an expectation: similar-looking situations will have similar outcomes. The rat doesn't need multiple experiences or reflection—one traumatic encounter is enough to establish the habit of avoidance.

The Crucial Point:

The rat is not reasoning logically about the situation. The rat is not thinking:

  • "That trap caused me pain"
  • "The future will resemble the past"
  • "Therefore, similar traps will cause similar pain"
  • "Therefore, I should avoid them"

Instead, the rat has an instinctive, automatic response based on custom and habit. The past experience has created a psychological association and an emotional response that guides future behavior.

The Illustration of Hume's Solution:

This shows that:

  1. Inductive inference doesn't require reason: The rat makes perfectly good inductive inferences (avoid future traps based on past experience) without any capacity for abstract reasoning or justification. The rat can't rationally justify its behavior, but that doesn't matter.
  2. Custom and habit work independently: The habit mechanism operates automatically, below the level of conscious reasoning. Experience creates expectations directly.
  3. Humans are like sophisticated rats: We're not fundamentally different. When we expect fire to be hot or bread to nourish us, we're operating on the same basic mechanism as the rat—custom and habit built by experience. We may add verbal justifications afterwards, but the underlying mechanism is the same instinctive expectation.
  4. Rational justification is unnecessary: The rat's inferences work perfectly well for survival despite lacking rational justification. Similarly, humans don't need to rationally justify induction for it to serve us well in life.
  5. Nature is sufficient: Nature has equipped both rats and humans with psychological mechanisms that produce reliable expectations about the world. This is enough for practical success—philosophical justification is superfluous.

The rat trap example thus demonstrates Hume's radical thesis: Our most sophisticated scientific reasoning rests on the same non-rational, instinctive foundations as a rat's simple learned avoidance. Reason is not the foundation of empirical knowledge; habit is.

300

Why is the distinction between justification and explanation particularly important in understanding Hume's theory of knowledge? Which does he provide for beliefs concerning matters of fact?

This distinction is absolutely central to understanding Hume's revolutionary approach to epistemology.

Justification vs. Explanation:

  • Justification (normative/rational): Providing reasons that show a belief is rationally warranted, legitimate, or that we ought to hold it. This is about rational entitlement—showing that a belief meets epistemic standards.
  • Explanation (descriptive/psychological): Describing the causal processes or mechanisms that produce a belief—showing why we in fact hold it. This is about psychological causation—showing what makes us believe.

The Traditional View (Pre-Hume):

Philosophers traditionally focused on justification. They asked: "Are our beliefs rationally justified?" "What reasons do we have for them?" "How can we show they're legitimate?" Epistemology was about normative standards for knowledge.

Hume's Revolutionary Move:

Hume separates these two questions and argues that for matters of fact beyond immediate perception:

  1. Justification is impossible: Our beliefs about matters of fact (causal connections, future events, unobserved objects) cannot be rationally justified. The problem of induction shows that inductive reasoning lacks rational foundation.
  2. But explanation is possible: We can still explain why we have these beliefs—through custom, habit, instinct, and natural psychological mechanisms. These explanations don't justify the beliefs, but they show why we inevitably hold them.

What Hume Provides:

For beliefs concerning matters of fact, Hume provides explanation, not justification:

  • He explains that we believe fire will be hot because of repeated past experience creating a habit of expectation
  • He explains that we believe in cause and effect because constant conjunction produces a feeling of necessary connection
  • He explains that we believe objects continue existing unperceived because imagination creates a fiction of continued identity

But he does not justify these beliefs—he explicitly denies they can be rationally justified.

Why This Distinction Matters:

  1. Changes the project of epistemology: Hume shifts philosophy from asking "Are our beliefs justified?" to asking "Why do we believe what we believe?" He replaces normative epistemology with descriptive psychology.
  2. Resolves apparent contradictions: Hume can simultaneously hold that (a) causal reasoning is unjustified, and (b) causal reasoning is inevitable and practically indispensable. There's no contradiction because he's making claims at different levels—justification vs. explanation.
  3. Avoids paralysis: If beliefs about matters of fact can't be justified, we might think we should abandon them. But Hume shows we can't—psychological mechanisms make them inevitable. Understanding the psychological explanation allows us to accept our limitations without falling into paralysis.
  4. Naturalistic turn: This moves philosophy away from rationalist ideals toward a naturalistic, scientific understanding of human cognition. We're natural creatures with natural belief-forming mechanisms, not pure rational agents.
  5. Undermines pretensions: Traditional metaphysics and theology often claimed to have justified beliefs about reality through pure reason. Hume's distinction exposes these claims as confused—what passes for rational justification is often just the operation of psychological habits.

The Bottom Line:

Hume is not in the business of justifying our beliefs about matters of fact—he thinks this is impossible. Instead, he explains why we inevitably hold them despite their lack of justification. This is a fundamental reorientation of philosophy from normative epistemology to descriptive psychology, and it's one of Hume's most important and radical contributions.

400

How does Hume explain ideas of imaginary things, e.g. unicorns and gold mountains?

Hume explains imaginary ideas through combination and recombination of simple impressions.

The mechanism:

  • We never have an impression of a unicorn or gold mountain
  • But we have impressions of: horses, horns, gold, mountains
  • The imagination can combine these simple ideas from real impressions into novel combinations
  • Unicorn = horse + horn
  • Gold mountain = gold + mountain

Key principles:

  1. All simple ideas derive from impressions: Every basic component (horse, horn, gold, mountain) comes from experience
  2. The imagination is creative but bounded: It can combine and rearrange simple ideas freely, but cannot create genuinely new simple ideas from nothing
  3. Complex ideas can be fictional: While every simple component must come from experience, the combinations themselves need not correspond to anything real

The limit: We cannot imagine something composed of elements we've never experienced. Someone born blind cannot imagine colors; someone who's never tasted pineapple cannot imagine that specific taste.

Significance: This preserves Hume's empiricist principle that all ideas trace back to impressions, even for fictional and imaginary concepts. The imagination is powerful but not magical—it can only rearrange and recombine what experience has provided.

400

Did Hume think we could have deductive knowledge of cause and effect? Why or why not? Can we have any rational justification whatsoever for our inferences concerning this relation? What does this mean for the possibility of knowledge concerning matters of fact and real existence?

No, Hume argues we cannot have deductive knowledge of cause and effect.

Why Not:

  1. Effects are not logically contained in causes: When we examine a cause (like fire), we cannot deduce its effect (heat) through reason alone. There is no logical contradiction in imagining fire without heat, or bread that doesn't nourish. The connection between cause and effect is not a matter of logical necessity.
  2. The opposite is always conceivable: For any causal relationship, we can conceive of the cause occurring without the effect, or with a different effect entirely. We can imagine billiard ball A hitting ball B, and ball B staying still, or flying upward, or disappearing. None of these scenarios involve logical contradictions.
  3. Experience is necessary: We only learn about causal connections through repeated observation—not through reasoning about concepts. Before experiencing fire, no amount of rational analysis of fire could tell us it produces heat.

Can we have ANY rational justification?

No—and this is Hume's radical conclusion.

Here's why: All causal reasoning depends on the principle that "the future will resemble the past" (Uniformity of Nature). But how can we justify this principle?

  • Not by relations of ideas: It's not a logical truth. There's no contradiction in imagining nature suddenly changing its course.
  • Not by experience/matters of fact: That would be circular—we'd be using past experience to justify the assumption that past experience is a reliable guide to the future.

This is the Problem of Induction, and Hume concludes it's insoluble. We cannot rationally justify inductive reasoning at all.

What this means for knowledge concerning matters of fact:

This is devastating for the possibility of knowledge (if knowledge requires rational justification):

  1. No knowledge beyond immediate perception: We cannot know anything about the past, future, or unobserved present with rational certainty.
  2. Science rests on unjustified assumptions: All scientific laws and predictions rest on inductive reasoning, which cannot be rationally justified.
  3. Radical skepticism about the external world: Even our belief in continuing objects and causal powers cannot be rationally justified.

However, Hume doesn't counsel despair. Instead, he offers a skeptical solution: Our causal inferences aren't justified by reason but by custom, habit, and natural instinct. We cannot help but make these inferences—they're part of our psychological nature. While not rationally justified, they are naturally inevitable and practically indispensable.

So knowledge in the strict sense (true, justified belief) concerning matters of fact is impossible. But belief, explanation, and practical success are still possible through our natural psychological mechanisms.

400

Given his skeptical solution to the problem of induction, what is the final status of Hume's own psychological theory of human nature? Is it rationally justified?

This question raises a fascinating self-referential problem for Hume's philosophy.

The Problem:

Hume's theory of human nature is itself an empirical theory based on observation and inductive generalization:

  • He observes how ideas associate in his own mind and in others
  • He observes how people form expectations based on experience
  • He generalizes from these observations to universal claims about human psychology

But according to his own skeptical conclusion, inductive inferences cannot be rationally justified. So Hume's theory cannot be rationally justified by his own standards!

The Status of Hume's Theory:

By his own account, Hume's psychological theory is:

  1. Not rationally justified: It's based on inductive generalization from observations, which cannot be rationally justified. He has no logical proof that all humans operate according to the principles he describes.
  2. Not knowledge (in the strict sense): If knowledge requires justified true belief, and his theory lacks justification, it's not knowledge.
  3. A product of custom and habit: Hume's belief in his own theory is itself formed by the same psychological mechanisms he describes—repeated observations have led him to expect that these patterns will continue.
  4. Explanatory rather than justified: The theory explains how we form beliefs but doesn't justify them. Similarly, the theory itself is an explanation of human nature that we adopt out of habit, not a justified body of knowledge.

Is This a Problem?

Not necessarily—in fact, it's consistent with Hume's skeptical resolution:

  1. The theory is self-exemplifying: Hume's theory is itself an example of the kind of belief it describes. Hume believes his theory based on custom and habit, not rational justification—just as the theory predicts!
  2. Practical adequacy: The theory doesn't need rational justification to be useful, predictively successful, or explanatorily powerful. Like the rat's inductive inferences, it can work well without philosophical justification.
  3. Honest skepticism: Hume is remarkably honest about the limitations of his own theorizing. He's not claiming to have discovered certain truths about human nature—he's offering an explanation that our natural habits lead us to accept.

The Broader Implication:

This reveals something profound about Hume's philosophical stance:

  • He's not claiming to have knowledge in the traditional sense
  • He's offering a naturalistic explanation of how humans actually think and form beliefs
  • He's replacing epistemology (theory of justified knowledge) with psychology (descriptive theory of belief-formation)
  • His whole project is descriptive rather than normative—he describes how we actually think, not how we should think according to some rational ideal

So the final status is: Hume's theory is an unjustified but practically useful, explanatorily powerful, and naturally compelling account of human nature. It's not knowledge, but it's the best we can do—and that's enough. This self-awareness about the limitations of his own theorizing is itself a mark of Hume's intellectual honesty and philosophical consistency.

400

Explain Hume's distinction between seeing humans as essentially active beings in contrast to seeing humans as essentially reasonable beings. Why doesn't Hume care much about reason ultimately?

Rationalists saw humans as essentially reasonable—reason distinguishes us from animals, should govern our lives, and can discover truth and determine right action.

Hume saw humans as essentially active—driven by passions, desires, and sentiments, not reason. His key arguments:

  • Reason is inert: It can't motivate action, only passions can ("reason is the slave of the passions")
  • Limited scope: Reason only discovers logical relations and traces cause-and-effect, but can't justify induction, determine values, or ground our fundamental beliefs
  • Most cognition is non-rational: Our crucial beliefs (causation, external objects) come from custom and instinct, not reason

Why Hume doesn't care much about reason: It's practically irrelevant for actual human life. Custom, habit, and passion do the real work. Reason can't justify our most important beliefs, and elevating it causes mischief (false metaphysical systems, dogmatism). Nature has equipped us with non-rational mechanisms that work perfectly well.

400

What does Hume think should be removed from the libraries and burned? Why?


The passage: Books containing neither (1) abstract reasoning about quantity/number nor (2) experimental reasoning about matters of fact should be "committed to the flames."

Target: Traditional metaphysics, scholastic philosophy, and speculative theology.

Why:

  • These works claim knowledge through pure reason about matters of existence—which is impossible
  • Their concepts (substance, essence, infinite being) don't derive from impressions, making them meaningless
  • They're "sophistry and illusion"—verbal tricks, not genuine knowledge
  • They cause dogmatism, intolerance, and waste intellectual energy

What survives: Mathematics/logic, natural sciences, history, and practical wisdom based on experience.

The point: A dramatic call to replace pretentious speculation with modest, empirically-grounded inquiry.