Natural deduction

Natural deduction is a way of using logical reasoning to prove facts. It is like a kind of game. In this game, you start with certain facts (called premises) and you use them to prove new facts (called conclusions). Then, you can use the new conclusions to prove even more facts, and so on. This process is called "deduction" because you use the facts you already have to figure out even more facts. All of your deductions have to be based on the facts that you started with, though, so you have to be careful not to make any wrong assumptions!