Deductive and Inductive Logic

Deductive reasoning is the process of reasoning from the general to the specific. Deductive reasoning is supported by deductive logic, for example:

From general propositions:

All ravens are black birds.

For every action, there is an opposite and equal reaction.

To specific propositions such as:

This bird is a raven, therefore it is black

This rifle will recoil when it is fired.

In contrast to inductive reasoning, the conclusions of deductive reasoning are as valid as the initial assumption. Deductive reasoning was first described by the ancient Greek philosophers such as Aristotle.

Inductive reasoning is the process of reasoning from the specific to the general. Inductive reasoning is supported by inductive logic, for example:

From specific propositions such as:

This raven is a black bird.

This rifle recoils when it is fired.

To general propositions:

All ravens are black birds.

For every action, there is an equal and opposite reaction.

In contrast to deductive reasoning, conclusions arrived at by inductive reasoning do not necessarily have the same validity as the initial assumptions.

- Source:  Wikipedia, at http://www.wikipedia.org/wiki/Inductive_reasoning