---
name: epistemology
description: "Master epistemology - the theory of knowledge, justification, and belief. Use for: knowledge, justification, skepticism, sources of knowledge, epistemic virtue. Triggers: 'knowledge', 'epistemology', 'justification', 'belief', 'Gettier', 'skepticism', 'certainty', 'evidence', 'testimony', 'perception', 'reason', 'a priori', 'empirical', 'reliability', 'internalism', 'externalism', 'foundationalism', 'coherentism'."
---

# Epistemology Skill

Master the theory of knowledge: What is knowledge? How is belief justified? Can we know anything?

## Core Questions

| Question | Issue | Stakes |
|----------|-------|--------|
| What is knowledge? | Analysis | Definition of knowledge |
| What justifies belief? | Justification | Epistemic norms |
| Can we know anything? | Skepticism | Scope of knowledge |
| What are sources of knowledge? | Sources | Perception, reason, testimony |

---

## The Analysis of Knowledge

### Traditional Analysis

**JTB**: Knowledge = Justified True Belief

```
S knows that P iff:
1. S believes that P (belief condition)
2. P is true (truth condition)
3. S is justified in believing P (justification condition)
```

### Gettier Problem

**Gettier Cases** show JTB is not sufficient:

```
GETTIER CASE #1
═══════════════

Smith has strong evidence that Jones will get the job
(told by company president).

Smith also knows Jones has 10 coins in his pocket.

Smith infers: "The man who will get the job has 10 coins
in his pocket."

Unknown to Smith: HE (Smith) will get the job.
And Smith happens to have 10 coins in his pocket.

Smith's belief is:
✓ Justified (by evidence about Jones)
✓ True (Smith will get job, has 10 coins)
✗ NOT knowledge (too lucky!)
```

### Post-Gettier Theories

**Fourth Condition Approaches**:
- No false lemmas
- Causal connection
- Defeasibility (no truths that would defeat justification)

**Tracking** (Nozick):
- S knows P iff: If P were false, S wouldn't believe P
- Sensitivity condition

**Safety** (Sosa, Pritchard):
- S knows P iff: S couldn't easily have been wrong
- In nearby possible worlds where S believes P, P is true

**Virtue Epistemology**:
- Knowledge = true belief from intellectual virtue
- Success attributable to cognitive ability

---

## Theories of Justification

### Foundationalism

```
FOUNDATIONALIST STRUCTURE
═════════════════════════

DERIVED BELIEFS
├── Justified by inference
├── From more basic beliefs
└── Not self-justifying

         ↑
         │
    BASIC BELIEFS
    ├── Self-justifying
    ├── Need no support from other beliefs
    └── Foundation of knowledge
```

**Basic Beliefs**:
- Classical: self-evident, incorrigible
- Modest: defeasibly justified without inference

### Coherentism

```
COHERENTIST STRUCTURE
═════════════════════

    ┌─────────────────────┐
    │                     │
┌───▼───┐           ┌─────┴───┐
│ Belief ├──────────►│ Belief │
│   A    │◄──────────┤   B    │
└───┬────┘           └────┬───┘
    │                     │
    │    ┌─────────┐      │
    └────► Belief  ◄──────┘
         │   C    │
         └────────┘

No foundations; mutual support
```

**Objection**: Coherent fiction could be well-justified but false (isolation problem)

### Infinitism

- No basic beliefs
- No circular justification
- Infinite regress is not vicious
- We can always provide further reasons

### Internalism vs. Externalism

| Internalism | Externalism |
|-------------|-------------|
| Justifiers must be accessible to subject | Justifiers may be external |
| What I can know by reflection | Reliable processes suffice |
| Epistemic responsibility | Connection to truth matters |
| Examples: evidentialism | Examples: reliabilism |

---

## Skepticism

### Cartesian Skepticism

```
SKEPTICAL ARGUMENT
══════════════════

1. I cannot know I'm not a brain in a vat (BIV)
2. If I know I have hands, I can deduce I'm not a BIV
3. If I can't know the conclusion, I can't know the premise
4. Therefore, I don't know I have hands

CLOSURE PRINCIPLE:
If S knows P, and S knows P→Q, then S can know Q
```

### Responses to Skepticism

**Moorean Shift**:
- I know I have hands
- If I have hands, I'm not a BIV
- Therefore, I know I'm not a BIV
- Common sense trumps skeptical premises

**Contextualism**:
- "Know" has different standards in different contexts
- In everyday contexts, we do know
- In philosophical contexts, standards are higher
- Both claims are true (in their contexts)

**Relevant Alternatives**:
- Knowledge requires ruling out relevant alternatives
- BIV is not a relevant alternative in normal contexts

---

## Sources of Knowledge

### Perception

**Direct Realism**: We perceive external objects directly
**Indirect Realism**: We perceive sense-data caused by objects
**Idealism**: Objects are mind-dependent

**Problems**:
- Perceptual error, illusion
- Skepticism about external world
- Theory-ladenness of observation

### Reason (A Priori Knowledge)

**Rationalism**: Some knowledge is innate or a priori
**Examples**: Mathematics, logic, conceptual truths

**Problems**:
- How do we access a priori truths?
- Are they merely analytic?
- Quine's attack on analytic/synthetic distinction

### Testimony

**Reductionism**: Testimony reducible to other sources
**Anti-Reductionism**: Testimony is fundamental source

**Conditions**: Speaker sincerity, competence, listener's critical uptake

### Memory

**Preservative**: Memory preserves justification
**Generative**: Memory can generate new knowledge
**Problems**: False memories, reliability

---

## Key Concepts

### Epistemic Virtues

| Virtue | Description |
|--------|-------------|
| Intellectual humility | Recognizing limits |
| Open-mindedness | Considering alternatives |
| Intellectual courage | Pursuing truth despite cost |
| Thoroughness | Careful investigation |
| Fair-mindedness | Impartial assessment |

### Evidence

**Evidentialism**: Justification proportional to evidence
**Evidence types**: Perceptual, testimonial, inferential

### Degrees of Belief (Bayesian)

- Credences: Degrees of belief (0-1)
- Conditionalization: Update on evidence
- Bayes' theorem: P(H|E) = P(E|H)·P(H)/P(E)

---

## Key Vocabulary

| Term | Meaning |
|------|---------|
| Justified | Having good reasons |
| A priori | Independent of experience |
| A posteriori | Dependent on experience |
| Analytic | True by meaning |
| Synthetic | True by world |
| Infallible | Cannot be wrong |
| Defeasible | Can be overridden |
| Propositional knowledge | Knowledge that P |
| Knowledge how | Practical knowledge |
| Epistemic luck | Being right by chance |
| Closure | Knowledge closed under known entailment |

---

## Integration with Repository

### Related Themes
- `thoughts/knowledge/`: Epistemological explorations
- `thoughts/consciousness/`: Perception, self-knowledge