One of the basic forms of valid reasoning is deductive reasoning. Inductive reasoning presents the argument from the specific to the general, whereas deductive reasoning presents the argument from the general to the specific. The basic premise of deductive reasoning is that if a particular thing holds true for a general class of things, then that same truth will apply to all the legitimate members of that particular class. The key would be in properly identifying the members of a class. Improperly making a categorization will result in an erroneous conclusion.
Deductive reasoning can be considered subtle and also a time-saving way of reasoning. By acknowledging that a particular class has a particular characteristic, each properly identified member of the class is already assumed to have that characteristic. There is no more need to examine each and every member of that class in order to find out if they possess the said characteristic. The validity of deductive reasoning means that it is possible to make assumptions that are efficient and useful.
One of the most common forms of deductive reasoning, and also one of its most useful forms, is syllogism. This form can be described in three easy steps: Every X has a characteristic Y; This particular thing is X; therefore, this thing has the characteristic Y. What this means is that:
• The first step identifies a definitive characteristic of X, whatever X may be.
• The second step identified that a particular thing fits in to the category that has been identified.
• The third step is the application of deductive reasoning, which connects the general truth that has been stated in Step 1 to the particular case that has been identified in Step 2.