The deductive method, deductive reasoning or deduction is a concept used in several areas and which is related to different ways of reasoning.
It is an information analysis process that brings us to a conclusion. In this way, deduction is used to find the final result.
The deductive method was already used in antiquity. The Greek philosopher Aristotle contributed to its definition through what became known as Aristotelian logic, which in turn is based on the doctrine of syllogism.
This is because since Aristotle, necessary conditions are found for true propositions, so that, finally, true conclusions can be obtained.
This method is often used to test existing hypotheses, called axioms, in order to prove theories, called theorems. Therefore, it is also called hypothetical-deductive method.
It is worth noting that the deductive method is used in philosophy, scientific law and education. We use this kind of reasoning when solving problems, for example, in physics and mathematics.
When the teacher demonstrates a problem on the board, he is using the deductive method. This is because he starts from a universal proposition, and through logical reasoning, arrives at a valid conclusion.
So, in this kind of logical reasoning, a conclusion is reached from the premises. Thus, the deductive method is considered “restricted or not very broad”, as it does not add new information to the conclusion, since it arises from what was already implicit in the premises.
Example
To better understand the application of this method, let's analyze the example below:
- Premise 1: The suspects in the crime were in the room between 1pm and 2pm.
- Premise 2: João was not in the room between 13 and 14 hours.
- Conclusion: Therefore, João is not one of the suspects in the crime.
Deductive and Inductive Method
Both deductive and inductive methods are two types of reasoning used to analyze whether information is valid or not.
Thus, through premises and propositions, it is analyzed whether there is a valid conclusion for what was stated. That's all, if the premises are true.
- deductive method: this argument is made from the biggest to smallest, that is, from a general premise towards another, particular or singular. The conclusions found in this method were already in the premises analyzed above and, therefore, it does not produce new knowledge.
- inductive method: this reasoning goes from smaller to larger or from one singular or particular premise to another, general one. Unlike the deductive method, where the conclusion is implicit in the premises, here your conclusion goes beyond these statements. Thus, the inductive method is broader and is widely used in science.
Read too:
- Scientific Method
- Aristotelian Logic
- Mathematical logic
- Truth table
- Syllogism