What is the deductive method?
It is known as deductive method or deductive reasoning to a type of logical reasoning that is characterized by drawing particular valid conclusions from a general premise or hypothesis.
This type of thinking operates when the conclusions are somehow “within” the premises. In addition, the reasoning must adequately formulate the procedure to infer them.
This means that the deductive method if it is carried out in a valid and correct way, and if the premises are in turn valid and true, will always yield valid and correct results. To guarantee this, deductive reasoning is governed by the rules of inference or transformation rules.
It is one of the most used modes of reasoning in mathematics.
See also: Argumentation
Origin of the deductive method
Deductive reasoning is attributed to Aristotle, the ancient Greek philosopher, who expressed it in its perfect logical form: the syllogism.
Later, this method was the protagonist of the reasoning of philosophers of the stature of Descartes, Spinoza, and Leibnitz.
It also served as the foundation for the composition of the scientific method, without which the contemporary notion of science would not exist.
Types of the deductive method
This method can be classified into:
- Direct and immediate conclusion. Cases in which the conclusion is obtained from a single necessary premise.
- Indirect and mediate conclusion. Cases in which the conclusion is obtained from two or more premises: a major one that contains a universal proposition, and a minor one that includes the particular proposition. In this case, the conclusion is the result of the contrast between the two.
Why is the deductive method important?
Deductive reasoning is one of the most commonly used in our daily lives. It is fundamental for the formulation of certain types of logic, such as symbolic or propositional logic.
In these types of logic lie the foundations of formal systems like the one that gave rise to computing. This is because mathematics uses deductive reasoning very often because its rules are fixed and immutable.
A deduction is understood to be the obtaining of valid, verifiable, communicable conclusions, based on one or more general premises. For example, to deduce q from a premise that states that p then q, we will have:
p then q (general premise)
if p, (particular premise)
then q (particular conclusion)
Sophism is understood as reasoning that in appearance, that is to say, logically, seems valid and true, but if we inspect the validity of its consequences, obviously they will not be true. They are also known as fallacies.
The insects have three pairs of legs.
Insects are animals.
Animals have three pairs of legs.
Differences with the inductive method
The fundamental difference between both methods is based on the logical path that they propose:
- The deductive method starts from general premises towards a particular conclusion. The conclusions are contained in the premises.
- The inductive method does the opposite, that is, it starts from particular premises to try to extrapolate a law or a general conclusion. The conclusions are obtained from a formulation of laws from a generalization.
The empirical-analytical method
This is the name given to a model of scientific research based on empirical logic and experimentation. It also includes the observation and controlled replication of natural phenomena, in favor of their statistical analysis.
It can help you: Empirical knowledge
The hypothetico-deductive method
The model of reasoning that supports the scientific method is known by this name. It is the research path that allows a degree of certainty and reliability in scientific knowledge.
This consists of several essential steps:
- Observation of nature to study.
- Creation of a hypothesis that explains its phenomena.
- Deduction of elementary propositions or consequences of the hypothesis itself.
- Experimental verification of the validity of the conclusions.
Abductive reasoning is one that from the description of a specific fact that is known, a hypothesis is reached or reached, that is, a probable explanation of the fact in the face of the premises that are or are known. According to some authors, this is the same as inference.