Deductive vs Inductive Reasoning

Two Different Approaches to Scientific Research

A scientist applies deductive reasoning in the course of research. Sometimes scientists take the inductive approach, or use a combination of the two.
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Deductive reasoning and inductive reasoning are two different approaches to conducting scientific research. Using deductive reasoning, a researcher tests a theory by collecting and examining empirical evidence to see if the theory is true. Using inductive reasoning, a researcher first gathers and analyzes data, then constructs a theory to explain her findings.

Within the field of sociology, researchers use both approaches. Often the two are used in conjunction when conducting research and when drawing conclusions from results.

Deductive Reasoning

Many scientists consider deductive reasoning the gold standard for scientific research. Using this method, one begins with a theory or hypothesis, then conducts research in order to test whether that theory or hypothesis is supported by specific evidence. This form of research begins at a general, abstract level and then works its way down to a more specific and concrete level. If something is found to be true for a category of things, then it is considered to be true for all things in that category in general.

An example of how deductive reasoning is applied within sociology can be found in a 2014 study of whether biases of race or gender shape access to graduate-level education. A team of researchers used deductive reasoning to hypothesize that, due to the prevalence of racism in society, race would play a role in shaping how university professors respond to prospective graduate students who express interest in their research. By tracking professor responses (and lack of responses) to imposter students, coded for race and gender by name, the researchers were able to prove their hypothesis true. They concluded, based on their research, that racial and gender biases are barriers that prevent equal access to graduate-level education across the U.S.

Inductive Reasoning

Unlike deductive reasoning, inductive reasoning begins with specific observations or real examples of events, trends, or social processes. Using this data, researchers then progress analytically to broader generalizations and theories that help explain the observed cases. This is sometimes called a "bottom-up" approach because it starts with specific cases on the ground and works its way up to the abstract level of theory. Once a researcher has identified patterns and trends amongst a set of data, he or she can then formulate a hypothesis to test, and eventually develop some general conclusions or theories.

A classic example of inductive reasoning in sociology is Émile Durkheim's study of suicide. Considered one of the first works of social science research, the famous and widely taught book, "Suicide," details how Durkheim created a sociological theory of suicide—as opposed to a psychological one—based on his scientific study of suicide rates among Catholics and Protestants. Durkheim found that suicide was more common among Protestants than Catholics, and he drew on his training in social theory to create some typologies of suicide and a general theory of how suicide rates fluctuate according to significant changes in social structures and norms.

While inductive reasoning is commonly used in scientific research, it is not without its weaknesses. For example, it is not always logically valid to assume that a general principle is correct simply because it is supported by a limited number of cases. Critics have suggested that Durkheim's theory is not universally true because the trends he observed could possibly be explained by other phenomena particular to the region from which his data came.

By nature, inductive reasoning is more open-ended and exploratory, especially during the early stages. Deductive reasoning is more narrow and is generally used to test or confirm hypotheses. Most social research, however, involves both inductive and deductive reasoning throughout the research process. The scientific norm of logical reasoning provides a two-way bridge between theory and research. In practice, this typically involves alternating between deduction and induction.