Deductive Reasoning Examples

What is Deductive Reasoning?
Deductive reasoning is one of the two basic forms of valid reasoning, the other one being inductive reasoning. The main difference between these two types of reasoning is that, inductive reasoning argues from a specific to a general base whereas deductive reasoning goes from a general to a specific instance. Also, deductive reasoning, unlike inductive reasoning, is something that is based on a premise and then follows accordingly. Inductive and deductive arguments differ with regard to the standards of evaluation that are applicable to them. Thus, deductive reasoning is the method by which conclusions are drawn on the basis of proofs and not merely by assuming or thinking about a predetermined clause. The basic principle on which deductive reasoning is based is:

All X are Y (premise)
All Y are Z (premise)
Hence, all X are Z (conclusion)

Similar relationships can be established by following a liner logic wherein one premise follows up on the other. Deductive arguments can only be valid or invalid, or true or false, because the statement that is derived may be true but in the context of the derived conclusion, it may not be valid. A deductive argument can be valid only if the conclusion necessarily follows from the premises given. If the conclusion is incorrect, then one of the premises must be faulty. A valid deductive argument with true premises is said to be sound, that is, a deductive argument which is invalid or has one or more false premises or both, are said to be unsound. An argument is valid when both the premises are true and the conclusion that is derived from them cannot be false.

Examples of Deductive Reasoning
Given below are a few examples that will help you understand this concept better:

All oranges are fruits
All fruits grow on trees
Therefore, all oranges grow on trees

All bachelors are single
Johnny is single,
Hence, Johnny is a bachelor

Sometimes, deductive reasoning can be established even without the help of syllogisms.

For example:
Everyday I go to work. This journey from my home to my office takes one hour. My office starts at eight o' clock in the morning. So, if I leave my home at seven o' clock in the morning, I will reach office in time.

There are also chances of deductive reasoning examples that go from specific to general. These are rare and generally have a lot of premises, each of which follow up on the previous one. Given below is one such example:

The members of Hassling family are Betty, Aaron and Lucas.
Betty is thin
Aaron is thin
Lucas is thin
Therefore, all members of the Hassling family are thin

With the help of these examples, you must have understood what deductive reasoning is. It may seem simple, but it can go wrong in ways more than one. When deductive reasoning leads to a faulty conclusion, the reason is often that the premise given was faulty. Thus, the premises used in deductive reasoning are in many ways the most important part of the entire process of deductive reasoning, as was proved by the help of the above given deductive reasoning examples. Thus, if they are wrong, the entire foundation of the whole line of reasoning is faulty and thus, the conclusions derived will also be faulty. However, at times, even if the logic is not executed properly, the conclusion may be wrong. So to minimize the chances of this mistake from happening, it is best to not assume anything and to only accept what has been mentioned.