Deductive Reasoning Examples

Conclusions are based on two types of reasoning – inductive and deductive. Inductive reasoning is when a general conclusion is drawn from a collection of specific observations. Here, truth is suggested but not ensured. On the other hand, deductive reasoning or deductive logic is where attempts are made to show that a conclusion logically follows a set of premises. They can be validated based on the premises if proven to be true. Deductive reasoning generally begins from a particular hypothesis or theory but the argument is never questioned. For example: An apple hit my head due to gravity! This is deductive logic based on the fact that gravity cannot be questioned and the apple falling on the head is proved because of this. To say that gravity works because an apple hit your head would be wrong. In this way, there are several examples to show the nature of deductive reasoning and to increase your knowledge on this subject. Read on to know more!

Examples Of Deductive Reasoning

The basic principle is:

All X is Y (premise)
All Y is Z (premise)
Therefore, all X is Z (conclusion)

Deductive reasoning is based on a concept called syllogism. It is a specific form of argument containing three steps. The first step states a definitive property that cannot be argued further. The second step states that a particular item/person fits into this category. The third and final step applies the deductive reasoning based on steps one and two and gives a conclusion.

All bachelors are single.
He is a bachelor.
Hence, he is single.

All bird feathers are light.
Parrot is a bird.
Hence, parrots have light feathers.

Every triangle has three sides.
The figure drawn here is a triangle.
So, the figure drawn here is a triangle and has three sides.

Earth is a planet.
All planets revolve around the sun.
Therefore, earth revolves around the sun.

To get a degree, one must have 120 credits.
John has 130 credits.
Hence, John has a degree.

I am a man.
All men must die.
Therefore, I must die.

In all the above statements, the arguments are both valid and sound. An argument is valid even if it is impossible for its premises to be true while its conclusion is false. An argument can be valid even though the premises are false. An argument is sound if it is valid and the premises are true. To show you the difference, here is an example of a valid but unsound argument.

All football players eat fish.
John eats fish.
Hence, John is a football player.

In this argument, what happens is the conclusion may or may not be true because the premises are false (since, all football players don’t have to eat fish; they can have other items as well).

Deductive reasoning without the help of syllogisms is also possible. For example:

Be careful of wasps, they might sting. Hence, it is understood that all wasps might sting.
Every day I go to work and it takes me one hour from home to office that begins at 8am. Hence, it is understood that if I leave at 7am, I will reach office at 8am.

Though most deductive reasoning is specifically based on fact and scientific logic, there are ones which are quite general also such as:

Members of a family include: John, Mathew and George.
John is thin.
Mathew is thin.
George is thin.
Hence, all members of the family are thin.

These are some of the examples of deductive reasoning. Hope they have cleared your doubts about the kinds of reasoning.

How to Cite

Related Articles

See also

More in 'Art & Entertainment'