Economists organize their discipline in fields from agricultural economics to urban economics. Many economists specialize in a field by publishing original essays on topics and teaching courses in a specific field.

The fields are in two sets: Those that develop core skills and those that emphasize application of the skills in specific settings. The core itself involves two modes of analysis. The Skills page gives simple examples. First, mathematical description of economic phenomena allows derivation of relationships. This mode of thought is called economic theory. Mathematics allows arguing by deductive reasoning from stated premises to a conclusion. It offers the internal consistency of mathematical proofs but requires no evidence of applicability.

The second core method looks for evidence based on observing economic phenomena. It draws inference from persistent patterns. A consistent pattern that is distinct from the complexity and randomness in nature is likely to have meaning.  This mode of thought is called inductive reasoning. It is the mode of analysis of economic historians, statisticians, and experimenters. The study of formal methods for drawing inferences from statistical evidence in economics is called econometrics.

Many advances in economic understanding come from the interaction between deduction and induction. When mathematical analysis yields new insights, the historians, statisticians, and experimenters look for ways to judge whether available evidence is consistent with the theory. When observation shows phenomena that are inconsistent with available theories, economic theorists look for new theories. The core fields are in item C on the list of fields shown below. » Read more: What are the fields in economics?