Philosophy of Mind, Brain and Behavior: Psychology as Science

Psychology as Science

Psychology as the Science of the Mind: Recall

  • What is the mind?
  • How does the mind relate to the body?
  • What defines the boundaries of the mind?
  • Philosophy of Mind Lectures 1-4 + Lecture 7
  • What is science?
  • Is psychology a science?
  • What makes for scientific progress?
  • How do values influence science?
  • Philosophy of Science Lectures 5-6

Is Psychology Really a Science?

  • Methodological Fetishism: Psychology prioritizes methodological rigor over theory formation.
  • Toothbrush Problem: There is no unifying theoretical foundation commonly accepted in psychology.
  • Divide Between Science and Practice: Psychological practice is often insufficiently grounded in psychological research.
  • Hard vs. Soft Sciences: Research in soft sciences (e.g., psychology, sociology, economy) requires less expert knowledge than research in hard sciences (e.g., physics).

Today’s Plan

  1. Science vs. Pseudoscience and the Problem of Demarcation
  2. Verificationism
  3. Falsificationism
  4. Ad Hoc & Auxiliary Hypotheses
  5. Theory-Ladenness of Observation

How can we evaluate whether psychology is a science?

The Demarcation Problem

  • The problem of drawing a line between the statements of the empirical sciences and all other statements (religious, metaphysical, or pseudoscientific).
  • Not: To distinguish true from false theories.
  • Rather: When should a theory be ranked as scientific? What are the criteria?

Science vs. Pseudoscience

  • Cronbach (1957) stated that science involves asking questions of nature and testing answers to determine soundness.
  • Scientific psychology's methods of inquiry qualify it as scientific, distinguishing it from philosophy or art.

Verificationism

  • Logical Empiricism: Verification
  • Moritz Schlick’s (1932) verifiability principle: A statement is meaningful if and only if it can be proved true or false, at least in principle, by means of experience.
  • We know the meaning of a statement if we know the conditions under which the statement is true or false.

Verificationism in Psychology

  • Arguments in Favor:
    • Seems to solve demarcation.
    • Example:
      • ‘The cat is grey’ vs. ‘the soul is immortal’
  • Examples:
    • He fidgets with his hands, and his gaze moves in many different directions.
    • He experiences anxiety.
    • These 600 students score high on openness to experience.
    • University students score high on openness to experience.

Problems with Verificationism

  • Problem 1: It’s too strict.
    • Excludes real sciences (rules out theoretical entities not directly observable—quarks, genes, gravity).
    • Response: Use verification and/or confirmation.
      • "All students in this room scoring high on extraversion study > 1 hour each day.” – Verify by showing studying > 1 hour each day is true across students in this room scoring high on extraversion.
      • “Students in this room scoring high on extraversion are more likely to study > 1 hour each day, compared to a control group.“ – Confirm by performing statistical analysis (significant group difference).
  • Problem: Too loose as a criterion. All sorts of pseudoscientific statements can be confirmed.
    • Example: Taurus horoscope, May 2025.

Falsificationism

  • A theory is scientific if its proponents can clearly state in advance what findings would refute the theory.
  • It is possible to find empirical evidence that conflicts with the theory’s claims and predictions, thus proving it wrong.
  • Why this criterion?
    • If a theory is not falsifiable, then the world can exhibit any properties, behave in any way, without this being in conflict with the theory.

Falsifiability

  • Popper (1963) argued that psychoanalytic theories were non-testable and irrefutable.
  • Clinical observations cannot confirm psychoanalytic theory any more than daily confirmations confirm astrology.
  • Freud's theories are like myths; they contain interesting psychological suggestions but are not testable.

Falsificationism and the Logic of Scientific Inference

  • Popper (1963): Every good scientific theory is a prohibition; it forbids certain things to happen. The more a theory forbids, the better it is.
  • Why this criterion?
    • Avoids Hume’s problem:
      • We can never prove empirical theories with certainty because they are always more general than our limited number of observations.
  • Inductive Inference (Induction)
    1. We generalize from particular instances.
    2. Not truth-preserving (uncertain)!
    • Example:
      • Premise 1: This is a person experiencing anxiety.
      • Premise 2: This person also reports lack of sleep. (Many times)
      • Conclusion: All people experiencing anxiety report lack of sleep.
      • Enumerative: Refuted by a single counterexample.
      • Probabilistic: The probability of people reporting lack of sleep, given they experience anxiety, is high. Not refuted by a single counterexample.
  • Deductive Inference (Deduction)
    • We deduce from a universal statement a particular case.
    • Truth-preserving! If the premises are true, then the conclusion must be true.
    • Example:
      • Premise 1: All people experiencing anxiety report difficulty sleeping.
      • Premise 2: This person is experiencing anxiety.
      • Conclusion: This person reports difficulty sleeping.

Falsifiability & Deductive Inference

  • Popper: The only thing that scientists can say with certainty is that a theory is wrong. You only need one observation or experiment.
  • “All people experiencing anxiety report difficulty sleeping” is falsifiable:
    • Find one anxious person who sleeps well, and the hypothesis would be refuted.
    • We could conclude with certainty: “Not all anxious people report sleep issues.”

Falsifiability as a Solution to the Demarcation Problem

  • Don’t look for confirmation but seek evidence that could disprove your theory.
  • A theory only remains valid as long as it withstands attempts to disprove it—but it is always possible for new evidence to refute the theory.
  • Scientific progress? – A process of continuous testing.

Clarification

  • Falsifiable vs. Falsified:
    • Falsifiable claim: Bears predictions that can be proven false.
    • Falsified claim: Actually has been disproven.
  • Verification: Seeking conclusive proof (H is true in all cases).
  • Confirmation: Showing that evidence supports a hypothesis (no definitive proof, probabilistic induction).
  • Falsification: Seeking to prove a statement false by finding a counterexample.

Examples

  • ‘CBT reduces symptoms of major depressive disorder more effectively than no treatment, as measured by standardized depression scales like the Beck Depression Inventory (BDI) over a 12-week period.’
    • Verifiable: makes a specific prediction (CBT reduces symptoms of depression) that can be empirically measured (using the BDI and a time frame of 12 weeks).
      • The statement would be verified if a well-designed study finds that participants receiving CBT show a statistically significant decrease in BDI scores compared to a control group after 12 weeks.
    • Falsifiable: there is some possible observation or experimental result that could show the statement is false.
      • The statement would be falsified if a well-designed study found no significant difference between the CBT group and the no-treatment group on the Beck Depression Inventory after 12 weeks.
  • ‘Everyone in this room has access-conscious states that influence their behavior.’
    • Verifiable but not falsifiable
  • ‘All green things are healthy.’
    • Falsifiable but not verifiable
  • ‘All participants in my experiment were 19 years, 2 months and 12 days old.’
    • Verifiable and falsifiable
  • ‘All psychology students currently enrolled in this course score high on Openness to Experience.’
    • Verifiable and falsifiable

Ad Hoc Adjustments

  • Ad hoc adjustments (also called ‘ad hoc hypotheses’ or ‘ad hoc assumptions’) are additions to a theory that:
    • are intended to protect the theory from falsification (explaining away the theory’s failures, as opposed to improving the theory);
    • which have no further consequences that were not already testable within the original theory.

EMDR: Controversy Around Effectiveness of Eye Movements

  • ‘Bilateral stimulation (eye movements) during recall reduces trauma-related distress.’
  • When tests found no effect…
    • Critics:
      • Eye movement = placebo
      • Benefits come from exposure or distraction
    • Proponents:
      • Control conditions = variants of EMDR
      • No effect is due to
        • Poor researcher training
        • Misapplication of EMDR protocols
    • Critics: You’re adding assumptions merely to protect EMDR against falsification!

Ad Hoc vs. Auxiliary Assumptions

  • Critics of falsificationism: It oversimplifies how science works.
  • Two distinct arguments:
    • Treatments can work before mechanisms are known (e.g., aspirin, psychotherapy). Utility justifies use. Science is what works, not necessarily what is well understood.
    • Prototypical cases of science do use additional assumptions that are intended to protect the theory from falsification…

The Discovery of Neptune

  • Leverrier: "It should be possible to see the new planet with good telescopes."
  • Sept 23-24, 1846: Galle discovered Neptune (after only thirty minutes of searching!)
  • "Monsieur, the planet whose position you indicated, really exists."
  • Leverrier: "I thank you for the diligence with which you have applied my instructions. Thanks to you, we are therefore definitively in possession of a new world."
  • Uranus' orbit was unexpected; it did not agree with Newton's theory.
  • Popper: This refutes Newton’s theory.
  • Leverrier: No. Was there another planet?
  • This was a risky prediction. Galle's observations were a real test. Newton’s theory passed the test in a ‘progressive’ way (new world-view).
  • Falsificationism is too strict: It excludes clear cases of science.

Theory-Ladenness of Observation

  • Verificationism and Falsificationism both assume: Empirical observations = neutral, objective, base for theory testing.
  • Is this really true though?

The Empiricist’s Justification of Science

  • What if scientific observation is influenced by scientists’ interests, experimental apparatus, and the theoretical concepts and beliefs scientists already hold?
  • What if data is not neutral?
  • O: No eye contact, no response to gestures.
    • Methodological behaviorist: The child has not been rewarded for social interaction.
    • Psychoanalyst: It’s a sign of repressed trauma.
    • Cognitive psychologist: It’s a sign of limited information processing.
    • Clinical psychologist: It’s a sign of autism spectrum disorder.

The Theory-Ladenness of Observation: fMRI Images

  • “The production of fMRI images requires extensive statistical manipulation based on theories about the radio signals, and a variety of factors having to do with their detection along with beliefs about relations between blood oxygen levels and neuronal activity, sources of systematic error, and more.” (Boyd & James 2025)
  • Theoretical assumptions à data production

Problems for Verificationism and Falsificationism

  • Circularity:
    • You cannot verify (falsify) a theory using observations that are themselves constructed by that theory.
    • That would be to confirm or test the theory by itself.
  • Worries:
    • Dogmatism (reasoning towards a predetermined conclusion);
    • Wishful thinking (using science to further a personal, social, or political agenda).

Birth Safety

  • What evidence is salient when comparing home vs. hospital births?
    • Mortality rates?
    • Intervention rates (e.g., c-sections)?
  • A study emphasizing a) and neglect b) may appear to favor hospital births as being safer, even though higher intervention rates in hospitals could have their own risks.
  • The decision to emphasize or neglect is not neutral.

Summary

  • The demarcation problem: how to distinguish science from pseudoscience? (E.g., psychology from astronomy)
  • Verificationism: To verify a statement or theory means to prove the truth of that statement or theory.
    • Problem: Too strict & too loose.
  • Falsificationism: Scientists should not look for confirmation but look for evidence that their theory is not correct.
    • Problem: Too strict. Excludes the use of admissible auxiliary assumptions that led to revolutionary scientific discoveries (Neptune).
  • Remaining issue: Theory-ladenness of observation

Next Week: Values in Science

  • Is science objective? How do values and biases influence scientific research?
  • Kuhn’s cyclic model and a-rationality of scientific change
  • Case study: the evaluative concept “mental illness”
  • Prepare:
    • Read Okasha, Chapter 5: “Scientific Change and Scientific Revolutions” (pp. 71-88)
    • Read Okasha, Chapter 7: “Science and its Critics” (pp. 113-130)
  • Submit assignment 2 by 19 May (23:59, Brightspace)