The two main methods of reasoning are called deduction and induction. Deduction works from the general to the more specific, where induction moves from the specific to the general.  In deduction, the conclusion logically follows from the premises; it is a necessary conclusion and is true. In induction, the conclusion "probably" follows the premises and is not necessarily true.
     The following examples are simple.  There is no need to go in to the multifaceted levels of deductive argumentation types.  That is for the student of formal logic.  Instead, all we need to know are the basics and we need to be able to apply the basics to our conversations and their defense of the Christian faith.

1. Deduction
   1. All men are mortal.  Socrates is a man.  Therefore, Socrates is a mortal.
   2. Every action God has ever done has been good.  God made the world.  Making the world was good.
   3. The book is on the table.  The table is on the floor.  Therefore, the book is above the floor.
2. Induction: 
   1. It has rained everyday on January 1st in Hawaii for the past several years.  Therefore, it will rain next year on that day as well.
      • Notice that the conclusion is reasonably sound, but not proven until after the fact.  The conclusion could be proven wrong.
   2. Every eagle I have observed has dark feathers.  Therefore, all eagles have dark feathers.
      • Just because all the eagles I have observed have dark feathers does not mean all eagles have dark feathers, though it might be true (If speaking of mature eagles).  However, there might be albino eagles, or eagles that are young that have down and no dark feathers.
   3. Each book I have seen in the library is more than a year old.  All the books in the library are over a year old.
      • It might be that all the books in the library are more than a year old.  But it is not necessarily so since we do not know if the first statement means that I have seen every book in the library.  If I have not seen every book in the library, and might be that there are books that are less than a year old.

     The difference between deduction and induction is very simple. Deduction generally means that all the conclusions drawn from the premises are accurate. However, as you will see in the next section on syllogisms (example four) this is not always the case.
     The reason you need to know the difference between deduction and induction is so that you can more clearly identify rational or irrational arguments. Unfortunately, a lot of people use induction as a substitute for deduction. You must be careful not to let someone make a conclusion that is too broad and is not necessarily required by the information from which it is drawn.   As you can see from the examples in induction above, the conclusions do not necessarily follow from the premises.
     As we progress through these lessons, you will see more instances of deduction and induction, particularly in the dialogues that we will analyze later.