Philosophical Assumptions: Selectionism, Determinism, Empiricism, Parsimony, and Pragmatism

Key Takeaways

  • The attitudes/assumptions of science include determinism, empiricism, experimentation, replication, parsimony, and philosophic doubt - know each by its decision implication.
  • Determinism assumes behavior is lawful and caused by identifiable variables, so the analyst keeps assessing rather than calling behavior 'random' or trait-driven.
  • Empiricism privileges objective observation and measurement over authority, intuition, or testimony alone.
  • Parsimony requires ruling out simple, established explanations before complex or novel ones; philosophic doubt keeps even well-supported conclusions tentative.
  • Selectionism explains behavior by consequences acting at three levels - phylogenic, ontogenic, and cultural.
Last updated: June 2026

Why the Assumptions Matter on the Exam

These assumptions are the operating system of behavior analysis: they decide what counts as an explanation, what counts as evidence, and what a BCBA does when a case is uncertain. Domain A items seldom say "this tests determinism." Instead they describe a team that calls behavior random, offers a mentalistic cause, or picks an intervention because it "sounds right," and ask for the best next step.

Cooper, Heron, and Heward describe two overlapping ideas: selectionism (the conceptual model of how behavior comes to be) and the attitudes of science (the working assumptions a scientist adopts). The attitudes include determinism, empiricism, experimentation, replication, parsimony, and philosophic doubt. Pragmatism - judging ideas by their practical, predictive, and useful consequences - is the truth criterion behavior analysis adopts (a position called contextualism or pragmatism).

Learn each assumption by its action implication, because that is what the exam rewards: not the definition you can recite, but the decision it drives.

The Core Assumptions and Their Action Implications

Assumption / AttitudeExam-Ready MeaningThe Move It Drives
SelectionismBehavior is selected by consequences across evolution, learning history, and cultureLook for reinforcement histories and current contingencies
DeterminismThe universe (including behavior) is lawful and orderly; events have causesKeep assessing; never label behavior 'random' or caused by inner traits
EmpiricismKnowledge comes from objective observation and measurementGather data before concluding; distrust authority alone
ExperimentationManipulate variables to reveal functional relationsTest, don't just guess; arrange comparison conditions
ReplicationRepeat to confirm effects are real, not coincidenceDon't trust a one-off result; repeat within and across cases
ParsimonyRule out simple, established explanations firstCheck definition, measurement, and obvious contingencies before exotic causes
Philosophic doubtHold all conclusions tentatively; keep questioningStay open to new data, even for 'settled' findings
PragmatismTruth is judged by useful, predictive consequencesChoose actions that improve prediction and socially meaningful outcomes

These are not optional flavors - they jointly define the behavior-analytic stance. An option that abandons any one of them (e.g., "the behavior is just random," violating determinism) is usually the wrong answer.

Selectionism and the Three Levels of Selection

Selectionism is the unifying model: behavior, like biological form, is shaped by selection by consequences. Skinner described three levels at which consequences operate:

  • Phylogenic (phylogenetic) selection - the evolutionary history of the species. Reflexes, unconditioned reinforcers (food, water), and predispositions reflect natural selection across generations.
  • Ontogenic (ontogenetic) selection - the learning history of the individual. Operant conditioning is selection within a lifetime: responses that contact reinforcement are 'selected' and recur in similar contexts.
  • Cultural selection - practices and customs that produce consequences for a group are passed on; metacontingencies describe how cultural practices are selected.

Exam application: when a stem mentions "why does this behavior persist," selectionism directs you to histories and consequences, not to inner motivation as a stopping point. A behavior recurs because, in this person's history and present environment, it has reliably produced reinforcement. Selectionism is also why behavior analysts emphasize current contingencies even when a long history exists - the environment continues to select moment to moment.

Determinism is the assumption that makes the search worthwhile: if behavior is lawful, there is a cause to find. Determinism does not claim every variable is easy to locate - only that 'random' and 'just his personality' are placeholders for an analysis you have not finished yet.

Determinism is the opposite of fatalism and of free-will explanations: it does not say the future is fixed regardless of what we do, and it does not invoke an uncaused 'will' inside the person. It says behavior is orderly and influenced by identifiable variables - which is precisely why arranging the environment can change behavior. On the exam, an option that calls a behavior 'unpredictable by nature' or attributes it to a 'choice' with no antecedent is usually betraying a non-deterministic stance and is the wrong answer.

Parsimony and Philosophic Doubt: The Two Most-Tested Attitudes

Parsimony (Occam's razor, applied) is a frequent trap. When a learner suddenly stops responding, the parsimonious BCBA first checks simple, well-established behavior-analytic possibilities before anything elaborate:

  • Unclear or changed instructions (SD problem)
  • Weak or satiated reinforcement (MO/EO/AO shift)
  • Unplanned extinction (reinforcer no longer delivered)
  • Measurement error (definition drift, miscount)
  • A skill deficit vs. a performance/motivation problem

Only after ruling these out would you entertain more complex accounts. Choosing the exotic explanation first violates parsimony and is usually the wrong option.

Philosophic doubt keeps the analyst honest: every conclusion is tentative and open to revision by new data. It is not cynicism or refusing to act; it is declining to treat any finding - even a published one or your own prior result - as beyond question. On the exam, the doubt-consistent answer is the one that keeps monitoring data and remains willing to revise the plan, rather than asserting certainty.

Pragmatism ties it together: behavior analysis judges an explanation by whether it lets you predict and influence behavior toward socially meaningful ends - not by how sophisticated it sounds. The most useful, parsimonious, data-supported account wins.

Test Your Knowledge

A teacher tells the BCBA, 'There's no point analyzing Devon's outbursts - they're completely random.' Which scientific attitude most directly contradicts this statement, and what should the BCBA do?

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Test Your Knowledge

A learner who mastered tacting colors suddenly responds incorrectly. A supervisee proposes the learner has 'lost interest due to an underlying mood disorder.' Which attitude of science does this proposal most clearly violate, and what is the better first step?

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Test Your Knowledge

Skinner's concept of selection by consequences operates at three levels. A cultural practice that spreads because it produces beneficial outcomes for a group is an example of selection at which level?

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Test Your Knowledge

Which response best reflects the attitude of philosophic doubt?

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