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IB DP Psychology — Research Methodology | SL & HL | Paper 3
🎯 Learning Intentions By the end of this note, you will be able to:
- Define deductive reasoning and inductive reasoning using IB-aligned terminology.
- Distinguish between deductive and inductive approaches to psychological research, identifying the key differences in logic, direction, and purpose.
- Explain how the deductive approach connects to hypothesis testing and the hypothetico-deductive model.
- Explain how the inductive approach connects to grounded theory and the emergence of patterns from data.
- Evaluate the strengths and limitations of each approach using relevant concept areas: Causality, Measurement, Bias, and Perspective.
- Apply deductive and inductive reasoning to a research scenario, identifying which approach is being used and justifying why.
- Discuss the relationship between research methodology and the choice of quantitative or qualitative methods.
- Analyse how the choice of deductive or inductive reasoning shapes the conclusions a researcher can draw.
Introduction & Context
Imagine you are a detective arriving at a crime scene. You have two options. You could begin with a theory — perhaps the crime was committed by someone with access to the building — and then look for evidence that confirms or refutes it. Alternatively, you could arrive with no assumptions at all, collect every piece of available evidence, and allow a picture of what happened to emerge gradually from the clues themselves. These two approaches represent fundamentally different ways of thinking, and they map almost perfectly onto the two major traditions in psychological research methodology.
Psychologists face exactly this choice every time they design a study. Do they begin with a theory and test it? Or do they begin with observations and build a theory from what they find? The answer shapes everything: what kind of data they collect, how they analyse it, what conclusions they can draw, and how confident they can be in those conclusions. Understanding the difference between these two approaches — deductive and inductive — is essential for evaluating any piece of psychological research.
In the IB Psychology 2027 syllabus, the concept of perspective is one of the six core concept areas used to analyse research. Deductive and inductive methodology sit at the heart of this concept area, because the approach a researcher takes reflects their assumptions about how knowledge is built, what counts as valid evidence, and what kind of understanding psychology should aim for.
🔍 Analogy — The Weather Forecaster vs. The Field Naturalist A weather forecaster uses established meteorological theory to predict tomorrow's weather: "If a low-pressure system moves in from the west, it will rain." They start with a theory and test whether the data confirms it. A field naturalist, by contrast, spends months observing a new species with no preconceptions, recording every behaviour they see, and only at the end asks: "What patterns have emerged? What theory can I build from this?" The forecaster is thinking deductively; the naturalist is thinking inductively. Both are valid — but they are asking fundamentally different kinds of questions.
Core Concepts
When researchers decide how to approach a question, they are making a choice about the direction of their reasoning. Do they move from the general to the specific, or from the specific to the general? This directional logic is what separates the two major