He used deductive reasoning to solve the problem.

Inductive reasoning is used to draw conclusions from specific instances.

For some reason, I couldn't sleep last night.

The reason why I love to travel is to explore new cultures.

He reasoned about the cause of the problem.

His confutation of the theory was well-reasoned and persuasive.

The reasons cited most often for not making the leap to a new career are fear and financial instability.