Deductive Reasoning

Deductive Reasoning

Deductive reasoning in science is the process of moving from a general principle or theory to a specific prediction that can be tested through observation or experiment. It’s often described as “top-down” logic.

1. General principle / theory → broad scientific law, model, or assumption.

2. Prediction → using logic, scientists deduce what must happen in a specific case if the principle is true.

3. Experiment / observation → test the prediction.

4. Evaluation → if results don’t match the prediction, the theory may need to be modified or rejected.

Example of Deductive Reasoning

• General principle: Newton’s law of gravitation says all masses attract each other with a predictable force. 

• Deduction: If this law is correct, then Comet Hale-Bopp (C/1995 O1) has an orbital period of about 2,533 years.That means after its spectacular visit in 1997, it won’t return to the inner solar system until around the year 4380.

• Test: Astronomers observe the sky, and the comet appears on schedule.

Sample Deductive Reasoning Activities

• Epidemiology - Contact tracing - Who is the source of the disease?

• Periodic Table of the Elements - Deduce the missing elements. 

• Atomic Radius - Predict relative atomic radii and reactivity of the elements (Nearpod lesson)

• Energy Transfer - Determine the unknown element

Inductive vs Deductive Reasoning