• When we require any knowledge system to do something it has not been explicitly told how to do it must reason.
• The system must figure out what it needs to know from what it already knows.
We have seen simple example of reasoning or drawing inferences already. For example if we know: Robins are birds.
All birds have wings. Then if we ask: Do robins have wings?
Some reasoning (albeit very simple) has to go on answer the question.

How can we reason?
To a certain extent this will depend on the knowledge representation chosen. Although a good knowledge representation scheme has to allow easy, natural and plausible reasoning. Listed below are very broad methods of how we may reason. We will study specific instances of some of these methods in the next few lectures.