Science Teaching Series

Internet Resources

I. Developing Scientific Literacy

II. Developing Scientific Reasoning

III. Developing Scientific Understanding

IV. Developing Scientific Problem Solving

V. Developing Scientific Research Skills

VI. Resources for Teaching Science

Deductive Reasoning

Whereas inductive reasoning draws general principles from specific instances, deductive reasoning draws specific conclusions from general principles or premises.  A premise is a previous statement or proposition from which another is inferred or follows as a conclusion. Unlike inductive reasoning, which always involves uncertainty, the conclusions from deductive inference are certain provided the premises are true. Scientists use inductive reasoning to formulate hypothesis and theories, and deductive reasoning when applying them to specific situations.  The following are examples of deductive reasoning.


Physics - electric circuits

  • first premise:  The current in an electrical circuit is directly proportional to the voltage and inversely proportional to the resistance (I=V/R).
  • second premise:  The resistance in a circuit is doubled.
  • inference:  Therefore, the current is cut in half.

Chemistry - element classification

  • first premise:  Noble gases are stable.
  • second premise:  Neon is a noble gas.
  • inference: Therefore, neon is stable.

Biologyplant classification

  • first premise: Monocot flower parts are in multiples of three.
  • second premiseApple flowers have five petals.
  • inference: Therefore, apple trees are not monocots.

Astronomy – planetary motion

Examples - See Sourcebook for Details