Reason

A man arrives late to work. His boss asks why. The man thinks for a moment and says, “The train was delayed because of a signal failure.” He does not blame anyone or make excuses. He simply gives a clear explanation for what happened. His boss now understands why he was late. What did the man give to his boss? He gave a reason for being late.

Reason means a logical explanation or justification for why something happened or failed to happen — it gives a sense of an action. Occasion, by contrast, means an event or situation that gives rise to something indirectly, providing an opportunity. So, reason focuses on the logical or explanatory cause behind an event. Occasion focuses on the circumstance that allows something to happen. In other words, reason is the explanation that makes sense of why something occurred; occasion is the opportunity or opening that lets something happen.