The difference between the inductive and deductive method lies in the direction of the reasoning to reach the conclusions.
Both the inductive and deductive methods are logical reasoning strategies, where the inductive method uses particular premises to reach a general conclusion, and the deductive method uses general principles to reach a specific conclusion.
Both methods are important in the production of knowledge. During a scientific investigation it is possible to use one or the other, or a combination of both, depending on the field of study in which it is carried out.
At present, the method used in experimental sciences is the so-called hypothetico-deductive method.
| Inductive method | Deductive method | |
|---|---|---|
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Definition |
It is a way of reasoning starting from a series of particular observations that allow the production of general laws and conclusions. | It is a way of reasoning and explaining reality from general laws or theories to particular cases. |
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Characteristics |
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Direction of reasoning |
From the particular to the general. | From the general to the particular. |
| Areas of knowledge |
It was the method used in the experimental sciences. Nowadays it is used as part of the scientific method in general. |
Formal sciences such as mathematics and logic. |
Inductive method
The inductive method is used starting from. particular cases to arrive at a general proposition.
The use of inductive reasoning was and is of great importance in scientific work in general, since it consists of collecting data on specific cases and analyzing them to create theories or hypotheses.
Characteristics of the inductive method
- It follows the bottom-up direction, from the particular to the general.
- It starts from empirical observations and then builds theories about what is observed.
- It is still used in the sciences, but within the hypothetico-deductive method.
- It is limited to the observation of phenomena.
- Its conclusions are probable and may turn out to be false.
Observation in the inductive method
Observation is one of the key aspects in the inductive method. The experience of phenomena is important in scientific areas where data are collected from observed facts and phenomena in order to arrive at a hypothesis or general theory.
For scientific knowledge to carry weight, it is important that numerous observations are made about a fact so that, if similar conditions exist, a generalization can be made.
In addition to observation, the inductive method uses experimentation to obtain the necessary data that lead to the statement of a general conclusion.
Steps of the inductive method
- Facts and phenomena are observed and recorded.
- Data collected from various observations and their possible relationships are compared and analyzed.
- Generalizations (or laws) are established.
- These generalizations are used to predict future phenomena.
Examples of the inductive method
A simple example is to find out the result of the sum of the internal angles of a triangle.
First, the internal angles of a triangle are added and it is noted that these result in 180º. Then, the same activity is performed with another triangle, and the result is the same, 180º. This action (observation and comparison of each sum) is repeated several times.
The result remains the same. When you gather all the information, you come to the general conclusion that the internal angles of a triangle add up to 180º. In other words, from this series of observations and their comparison, it is concluded that this will continue to occur.
Another example is given when it is observed that all objects that rise tend to fall. If you take a series of objects and then let them fall, you observe that every one of them falls towards the floor. This leads to the conclusion that there must be some property or force that causes the objects to attract each other (in this case the mass of each object).
It was thus that, through this type of observations, it was established the law of gravityformulated by the English natural physicist Isaac Newton (1643-1727). This law basically proposes that all bodies possessing mass attract each other. This is how Newton proved it through several observations. It can be said, then, that “every body that goes up must come down”.
Limitations of the inductive method
Science is constantly developing. Even with general laws that predict events or phenomena, those engaged in science know that there may be cases in which the general laws of science may not be applicable. conclusions do not apply.
This is why the inductive method as such may be insufficient when it comes to building knowledge and broadening the understanding of reality, if its conclusions are not constantly tested.
According to the Scottish philosopher David Hume (1711-1776), there is no absolute certainty that what we observe a certain number of times will be repeated in the same way in the future.
For the Austrian philosopher of science Karl Popper (1902-1994), the problem of induction lies in the fact that it is not always possible to establish a universal truth, starting from particular observations. For Popper, the important thing is to find facts that can be falsify (refute) conclusions in the sciences.
A famous example is the statement “all swans are white”. At one time in Europe this was believed to be the case. It was observed that swans were characterized as all white, and this statement became generalized as a fact.
This was because there was no experience to the contrary (black swans had never been seen). However, some time later, black swans were brought from Australia to Europe, and this simple fact disproved the idea that all swans were white.
You may also be interested to see Objective and subjective.
Deductive method
The deductive method is a type of reasoning used to. apply laws or theories to singular cases.
It is the method used in the formal sciences, such as logic and mathematics. In addition, deductive reasoning is key in the application of laws to particular phenomena studied in science.
It is a hierarchical form of reasoning, since it starts from generalizations, which are gradually applied to particular cases. This makes the deductive method very useful for producing knowledge from previous knowledge. It is also practical when it is impossible or very difficult to observe the causes of a phenomenon, but only those consequences that it produces.
Characteristics of the deductive method
- It follows the direction from top to bottom, from the general to the particular.
- It is the method used in the formal sciences.
- It is based on theory to predict observable phenomena by means of hypotheses.
- The conclusion is contained in the premises.
- If the premises are valid and true, the conclusion is also valid and true.
- Its conclusions must lead to logical and rigorous consequences.
- By itself it does not produce new knowledge.
Examples of the deductive method
A classic example of this method is the following:
- Premise 1: All men are mortal.
- Premise 2: Socrates is a man.
- Conclusion: Therefore, Socrates is mortal.
It is possible to observe that the conclusion is already implicit in the premises.
Another example is presented when thinking about living beings and their genetics. It is known that all living beings possess DNA (deoxyribonucleic acid). Therefore, if at some point in time a living organism is going to be analyzed, it follows in advance that this organism will have DNA.
Validity and veracity in the deductive method.
In the deductive method, erroneous conclusions may be drawn if the premises are not true. For example, considering the following premises:
- Premise 1: All men are evil.
- Premise 2: Your grandfather is a man.
- Conclusion: Therefore, your grandfather is bad.
This argument is validhowever, is not true. Its validity lies in the fact that the conclusion is implicit in the premises. But the statement contained in premise 1 (“all men are evil”) is not a true statement, since its veracity does not follow from the premises, so it is still necessary to check it.
In this sense, the conclusions of the deductive method are valid and correct when the premises are also valid and correct. In the same way, if the premises are true, the conclusion will also be true.
Hypothetico-deductive method
The method currently used in scientific research is the so-called hypothetico-deductive method. This method basically synthesizes the main aspects of the inductive and deductive methods.
Steps of the hypothetico-deductive method.
- The hypothetical-deductive observation and analysis of a series of phenomena.
- We propose a hypothesis according to the results of what was observed in order to explain these phenomena. For the hypothesis to be valid, it must be possible to test it.
- When a hypothesis postulates something, it is deduces that if the same conditions that caused a phenomenon occur, the consequences that the hypothesis predicts should occur.
- See check the hypothesis from experiments.
- If the hypothesis is verified, then is accepted. If its assumptions are not verified, is rejected.
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