Overview

The debate between internalism and externalism in epistemology concerns the conditions for epistemic justification. It asks whether the factors that justify a belief must be accessible to the believer’s mind (internalism) or if they can depend on external factors like the reliability of the cognitive process (externalism).

Core Idea

  • Internalism: Justification depends on factors internal to the subject’s perspective (e.g., mental states, reflection). If you are justified, you can know why you are justified.
  • Externalism: Justification depends on the objective relationship between the belief and the world (e.g., a reliable process), regardless of whether the subject is aware of it.

Formal Definition

  • Internalism: The view that a subject’s justification for a belief is determined solely by factors that are internal to the subject’s mind or accessible upon reflection.
  • Externalism: The view that at least some factors determining justification are external to the subject’s mind (e.g., the reliability of the belief-forming mechanism).

Intuition

  • Internalist Intuition: If a brain in a vat has the exact same experiences as a normal person, they should be equally justified in their beliefs (even if the brain in a vat is wrong), because their internal perspective is identical.
  • Externalist Intuition: A chicken sexer who reliably sorts chicks but thinks they are just guessing (“blind sight”) knows the sex of the chicks, even if they don’t have internal access to how they know.

Examples

  • The Clairvoyant: An internalist might say a clairvoyant who reliably predicts the future but has no reason to believe they are clairvoyant is not justified. An externalist might say they are justified because the process is reliable.
  • The New Evil Demon: If a demon deceives you so your experiences are perfect hallucinations, an internalist says you are still justified in your beliefs (you are doing your best). An externalist might say you are not justified because the link to truth is broken.

Common Misconceptions

  • Misconception: Internalism means “subjective” and Externalism means “objective.”
    • Correction: Both aim for objective knowledge; the difference is about the conditions required for justification.
  • Misconception: Externalists don’t care about evidence.
    • Correction: Externalists often value evidence, but they don’t think the subject necessarily needs to know that the evidence is reliable for it to confer knowledge.
  • Reliabilism: A major form of externalism holding that a belief is justified if it is produced by a reliable cognitive process.
  • Accessibilism: A form of internalism requiring that the justifier be accessible to the subject.
  • Mentalism: A form of internalism requiring that justifiers be mental states.

Applications

  • Artificial Intelligence: Can an AI “know” something just by processing data reliably (externalism), or does it need “awareness” of its reasons (internalism)?
  • Animal Knowledge: Externalism easily accounts for animal knowledge (a dog knows its master is home), whereas internalism struggles because animals may not reflect on reasons.

Criticism and Limitations

  • Internalism: Criticized for leading to skepticism (since we can’t prove our internal states match reality) and for over-intellectualizing knowledge.
  • Externalism: Criticized for allowing “accidental” knowledge (like the clairvoyant) that seems irrational from the subject’s perspective.

Further Reading

  • Epistemic Justification by Laurence BonJour
  • Reliabilism and Contemporary Epistemology by Alvin Goldman
  • Internalism and Externalism in Epistemology (Internet Encyclopedia of Philosophy)