What is the deductive method?

What Does Deductive method Mean

We explain what the deductive method is and the ways in which it can be used. Also, examples and what is the inductive method.

The deductive method draws logical conclusions from a set of premises.

What is the deductive method?

We speak of the deductive method to refer to a specific form of thought or reasoning , which draws logical and valid conclusions from a given set of premises or propositions . It is, in other words, a way of thinking that goes from the most general (such as laws and principles) to the most specific (concrete facts).

According to this way of thinking, the conclusions of an argument are given in advance in its own premises, so it only requires an analysis or breakdown of these to know the result. In order to do so, the premises must be considered true , since their validity will depend on whether or not the conclusions are also true.

The deductive method can be used in two ways:

  • Direct In this case, the starting point is a single premise that is not contrasted with others around it.
  • Hint. In this case, the starting point is a couple of premises: the first contains a universal statement and the second a particular one; from the comparison of both the conclusion is obtained.

In this way, it should be noted that the validity of the premises will determine that of the conclusions : it is possible to start from wrong premises and draw wrong conclusions, without the logic of reasoning being wrong for that reason.

On the other hand, this method gives rise to two other more complex methods, which are:

  • Axiomatic-deductive method. A set of theorems (propositions) is extracted from a set of axioms (premises) given in advance, using a series of logical reasoning.
  • Hypothetical-deductive method. From the observation of a phenomenon, an interpretive hypothesis is ventured that is then subjected to comparison by deductive logical reasoning. This is the method that scientific knowledge uses .

See also: Scientific method

Examples of the deductive method

The validity of the premises will determine that of the conclusions.

Most syllogisms are a perfect example of the deductive method. Let's see some:

  • Premise 1. All dogs are deadly. Premise 2. Pluto is a dog. Conclution. Pluto is mortal.
  • Premise 1. No cow can fly. Premise 2. Animals that fly have wings. Conclution. Cows do not have wings.
  • Premise 1. Venezuelans are Caribbean. Premise 2. María is Venezuelan. Conclusion: Maria is Caribbean.
  • Premise 1. Planets are round. Premise 2. Earth is a planet. Conclution. The earth is round.
  • Premise 1. The murderer was a white male. Premise 2. The maid is a Chinese woman. Conclution. The maid is not the killer.

What is the inductive method?

The inductive method uses the observation, recording and contrast of information.

The inductive method is the opposite or opposite to the deductive one, and therefore it goes from the most particular to the most general. That is, the observation, registration and contrast of information is used to build general premises that can serve as support or explanation.

That is, the inductive method works from generalizations, supported by specific observations , that is, the other way around. For example:

Premise 1. My father died. Premise 2. My father was a man. Conclution. Men die.

More in: Inductive method

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