Types of Knowledge in Philosophy

Why This Matters

When philosophers ask "What can we know?" they're really asking several distinct questions—and the answer depends entirely on what kind of knowledge we're talking about. The distinctions between propositional, procedural, and acquaintance knowledge aren't just academic hair-splitting; they reveal fundamentally different relationships between the knower and what is known. You're being tested on your ability to recognize these distinctions and explain why they matter for epistemological debates about justification, truth, and belief.

These categories also connect to larger questions you'll encounter throughout the course: How do rationalists and empiricists disagree about knowledge sources? What role does experience play in different types of knowing? Can something count as knowledge if you can't put it into words? Don't just memorize definitions—know what epistemological problem each type of knowledge helps us understand and how they relate to the classical analysis of knowledge as justified true belief.

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Knowledge by Object: What Are We Knowing?

The most fundamental distinction in epistemology concerns what kind of thing we claim to know—a fact, a skill, or a person/thing directly. This three-way distinction, developed by Bertrand Russell and Gilbert Ryle, shows that "knowledge" isn't a single phenomenon.

Propositional Knowledge (Knowing That)

• Expressed in declarative statements—claims like "Paris is the capital of France" that can be evaluated as true or false
• Central to the JTB analysis—this is the type of knowledge philosophers mean when debating whether knowledge requires justified true belief
• Requires epistemic standing—you must have reasons or evidence, not just a lucky guess that happens to be correct

Procedural Knowledge (Knowing How)

• Demonstrated through skilled action—riding a bike, speaking a language, or playing chess involves knowledge that isn't reducible to facts
• Ryle's challenge to intellectualism—Gilbert Ryle argued this shows not all knowledge is propositional, sparking ongoing debate
• Acquired through practice—often cannot be learned from instruction alone, suggesting a distinct cognitive category

Acquaintance Knowledge (Knowing Of)

• Direct, unmediated familiarity—knowing a person, a city, or the taste of coffee through firsthand experience
• Russell's foundation for knowledge—Russell argued acquaintance provides the basic building blocks from which other knowledge is constructed
• No propositional structure required—you can know of something without holding any particular beliefs about it

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Knowledge by Source: How Do We Know It?

Epistemologists fiercely debate where knowledge comes from. This distinction—between what we can know through reason alone versus what requires experience—defines the rationalist-empiricist divide that shapes modern philosophy.

A Priori Knowledge

• Independent of experience—truths like "all bachelors are unmarried" or "$2 + 2 = 4$" can be known through reason alone
• Associated with necessity—a priori truths couldn't have been otherwise; they hold in all possible worlds
• Rationalist cornerstone—Descartes, Leibniz, and Kant argued that significant knowledge (mathematics, logic, metaphysics) is a priori

A Posteriori Knowledge

• Dependent on experience—claims like "water boils at 100°C" require observation to verify
• Contingent truths—a posteriori facts could have been different; they depend on how the world actually is
• Empiricist foundation—Locke and Hume argued that all substantive knowledge ultimately traces back to experience

Empirical Knowledge

• Grounded in sensory observation—what we learn through seeing, hearing, touching, and measuring the world
• Scientific method's basis—forms the foundation for hypothesis testing, experimentation, and data collection
• Vulnerable to skeptical challenges—Descartes' dream argument and Hume's problem of induction target this type specifically

Rational Knowledge

• Derived through logical deduction—conclusions reached by applying valid inference rules to premises
• Includes mathematical and logical truths—proofs in geometry or formal logic exemplify purely rational knowledge
• Certainty claim—rationalists argue this type of knowledge is more secure than empirical knowledge because it doesn't depend on fallible senses

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Knowledge by Cognitive Process: How Is It Formed?

Beyond sources, epistemologists distinguish knowledge by the mental processes that produce it. Some knowledge arrives immediately; other knowledge requires chains of reasoning.

Intuitive Knowledge

• Immediate and non-inferential—grasped directly without conscious reasoning, like recognizing a face or sensing danger
• Self-evidence claims—some philosophers argue basic logical axioms or moral truths are known intuitively
• Epistemologically controversial—critics question whether intuition provides genuine justification or merely psychological certainty

Inferential Knowledge

• Derived through reasoning—conclusions reached by drawing logical connections from premises or evidence
• Deductive and inductive forms—includes both necessary conclusions (deduction) and probable conclusions (induction)
• Regress problem trigger—if all inferential knowledge requires prior knowledge, what grounds the chain? This generates the foundationalism vs. coherentism debate

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Knowledge by Articulation: Can It Be Expressed?

Some knowledge resists verbal expression entirely. This distinction matters for understanding expertise, skill transfer, and the limits of propositional analysis.

Tacit Knowledge

• Implicit and unarticulated—the expert's "feel" for a situation, the native speaker's grammatical intuitions, the scientist's sense of a promising hypothesis
• Polanyi's insight—Michael Polanyi argued "we know more than we can tell," challenging the assumption that all knowledge is statable
• Crucial for expertise—explains why masters can't always teach what they know and why some knowledge transfers only through apprenticeship

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Quick Reference Table

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Self-Check Questions

1. A skilled surgeon knows exactly where to cut but struggles to explain her decision-making process to students. Which two types of knowledge best describe what she possesses, and why do they resist verbal instruction?

2. Kant claimed that "$7 + 5 = 12$" is synthetic a priori knowledge. Explain what this means by contrasting a priori with a posteriori knowledge and why this claim was philosophically revolutionary.

3. Compare and contrast acquaintance knowledge and propositional knowledge. Why might Russell have considered acquaintance knowledge more epistemologically basic?

4. If an FRQ asks you to explain the regress problem for justification, which distinction between types of knowledge (intuitive vs. inferential) becomes most relevant, and why?

5. A scientist "just knows" her hypothesis is on the right track before running experiments. Identify which type(s) of knowledge this represents and evaluate whether it could count as genuine knowledge under the JTB analysis.