Methods of ObservationWhat is Science?The Scientific EnterpriseTheoryPlausibility of PremisesScience is a series of “boxes within boxes”HypothesesTestsExplanation v. PredictionWho’s Right?GeneralizationDeductive v. Inductive ReasoningWhat can we learn by “observing”?Observation InferenceDescriptive Inference: Or how do we know what we saw?Descriptive Inference IIDescriptive Inference IIIInduction I: Empirical LawsInduction II: Thick DescriptionInduction III: InterpretationConclusionMethods of Methods of ObservationObservationPS 204A, Week 2PS 204A, Week 2What is Science?What is Science?Science is: Science is: Based on natural laws/empirical Based on natural laws/empirical regularities.regularities.Makes predictions.Makes predictions.Collections of laws that generate predictions Collections of laws that generate predictions that are empirically confirmed constitute that are empirically confirmed constitute “explanations.” “explanations.” Must be falsifiable.Must be falsifiable.Is always tentative (move from grossly Is always tentative (move from grossly wrong to more subtly wrong theories).wrong to more subtly wrong theories).The Scientific EnterpriseThe Scientific EnterpriseGeneralizationTheoryObservationHypothesisTheoryTheoryTheories always possess a Theories always possess a “theoretical notion” or analogy “theoretical notion” or analogy that simplifies reality.that simplifies reality.This analogy is embodied in This analogy is embodied in the assumptions or premises of the assumptions or premises of the theory. Assumptions are the theory. Assumptions are themselves unobservable – and themselves unobservable – and known to be simplifications known to be simplifications (e.g., individuals are rational, (e.g., individuals are rational, states are unitary actors). states are unitary actors). Prefer plausible over less Prefer plausible over less plausible premises.plausible premises.Since premises are never Since premises are never “true” or, at least, are “true” or, at least, are unobservable, theories are unobservable, theories are never true, only more or less never true, only more or less useful.useful.Utility is defined by the Utility is defined by the number of empirically number of empirically supported propositions the supported propositions the theory generates.theory generates.GeneralizationTheoryObservationHypothesisAnalogyPlausibility of PremisesPlausibility of PremisesIf in theories, premises are things we do If in theories, premises are things we do not agree on and are unobservable, how not agree on and are unobservable, how do we assess their plausibility?do we assess their plausibility?Utility of their predictions (Friedman).Utility of their predictions (Friedman).Accordance with natural laws.Accordance with natural laws.Transform premises into objects of Transform premises into objects of investigation that are themselves the investigation that are themselves the subjects of theories. subjects of theories. Theory of rationality.Theory of rationality.Theory of unitary states. Theory of unitary states.Science is a series of “boxes Science is a series of “boxes within boxes”within boxes”Balance of power theory: Balance of power theory: international system is anarchic and international system is anarchic and composed of unitary states wishing composed of unitary states wishing only to survive. only to survive. Anarchy: no common authorityAct to check the power of other states.Unitary states wishing to surviveInternal hierarchy: state “speaks” with a single voiceWithin any given “box,” we take the premises as “given.” But any premise may itself become an object of investigation in another “box.” If testing leads to a revision of a premise, then still need to plug back into original theory and retest.HypothesesHypothesesPropositions are general Propositions are general statements that follow statements that follow logically from the logically from the premises.premises.Hypotheses are Hypotheses are propositions that contain propositions that contain only observable variables only observable variables (i.e., if X, then Y, when (i.e., if X, then Y, when both X and Y can be both X and Y can be observed).observed).Central issue is deductive Central issue is deductive validity: Does the validity: Does the hypothesis follow logically hypothesis follow logically and axiomatically from and axiomatically from the premises?the premises?GeneralizationTheoryObservationHypothesisDeductive ValidityTestsTestsWe test theories by We test theories by examining whether the examining whether the hypotheses they hypotheses they generate are supported generate are supported by the evidence. We by the evidence. We make the observations make the observations the theories imply.the theories imply.Conclusion validity: is Conclusion validity: is there a relationship there a relationship between X and Y? between X and Y? Internal validity: is the Internal validity: is the relationship causal?relationship causal?Construct validity: do the Construct validity: do the observable measures observable measures capture concepts in the capture concepts in the theory appropriately?theory appropriately?GeneralizationTheoryObservationHypothesisTest1. Conclusion Validity2. Internal Validity3. Construct ValidityExplanation v. PredictionExplanation v. PredictionTheory offers an explanation for observed Theory offers an explanation for observed facts and predicts new facts that, once facts and predicts new facts that, once confirmed, are also explained.confirmed, are also explained.Theories must be potentially falsifiable. Theories must be potentially falsifiable. Popper/Hempel insist that known facts Popper/Hempel insist that known facts cannot falsify a theory. Therefore, cannot falsify a theory. Therefore, prediction is the goal of all science. prediction is the goal of all science. Alternatively, Snyder argues that if Alternatively, Snyder argues that if scientific evidence is objective, evidence scientific evidence is objective, evidence is evidence independent of the timing of is evidence independent of the timing of it’s discovery relative to the theory.it’s discovery relative to the theory.Who’s Right?Who’s Right?All evidence helps corroborate a All evidence helps corroborate a theory, even known facts.theory, even known facts.Predictions are more