The difference between the inductive and deductive method lies in the direction of the Reasoning to reach conclusions.
Both the inductive and deductive methods are logical reasoning strategies, with the inductive using particular premises to reach a general conclusion, and the deductive using general principles to reach a specific conclusion.
Both methods are important in the production of knowledge. During a scientific investigation it is possible that one or the other is used, 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
Definition
It is a way of reasoning based on a series of particular observations that allow the production of laws and general conclusions. It is a way to reason and explain reality based on general laws or theories towards particular cases.
Characteristics
It is based on the observation of facts and phenomena. Generalize from your observations. His conclusions are probable. Its objective is to generate new knowledge. Draw conclusions from generalizations. In logic, the conclusion of an argument is included in the premises. It is useful when the causes of a phenomenon cannot be observed. His conclusions are rigorous and valid. It does not generate new knowledge by itself, since it starts from verifying previous knowledge.
direction of reasoning
From particular to general. From the general to the particular. Knowledge areas
It was the method used in the experimental sciences. Today 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 the collection of data on specific cases and its analysis to create theories or hypotheses.
Characteristics of the inductive method
Follow the direction from the bottom up, from the particular to the general. Part of empirical observations and then build theories about what is observed. It is still used in science, but within the hypothetico-deductive method. It is limited to the observation of phenomena. Their 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 the phenomena is important in the scientific areas where data of facts and observed phenomena are collected, to arrive at a hypothesis or general theory.
For scientific knowledge to have weight, it is important that numerous observations be made about a fact so that, if similar conditions occur, a generalization can be made.
In addition to observation, the inductive method uses experimentation to obtain the necessary data that leads to 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 interior 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 carried out 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 all the information is gathered, the general conclusion is reached that the interior 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 a series of objects is picked up and then dropped, each one is observed to fall towards the floor. In this way, the conclusion is reached that there must be some property or force that makes objects attract each other (in this case the mass of each object).
Thus, through these types of observations, the law of gravity, formulated by the English naturalist physicist Isaac Newton (1643-1727). This law basically proposes that all bodies that have mass attract each other. This was how Newton verified it through various observations. It can be said, then, that “every body that goes up has to come down.”
Limitations of the inductive method
For a long time it was believed that all swans were white because black swans had never been observed. This is an example of the limitations of the inductive method to generalize observations.
Science is constantly developing. Even with general laws that predict events or phenomena, those in science know that there may be cases where the 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 induction problem lies in the fact that it is not always possible to establish a universal truth, based on particular observations. For Popper, the important thing is to find facts that can fake (refute) conclusions in science.
A famous example is the statement “all swans are white”. At some point in Europe it was believed that this was so. It was observed that the swans were characterized by being all white, generalizing this statement as a fact.
This is because there was no experience to the contrary (black swans had never been seen). However, some time later, specimens of black swans were brought from Australia to Europe, and this simple fact refuted the idea that all swans were white.
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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 formal sciences, such as logic and mathematics. Furthermore, deductive reasoning is key in applying laws to particular phenomena that are studied in science.
It is a hierarchical form of reasoning, since it is based on generalizations, which little by little are applied to particular cases. This makes the deductive method very useful for producing knowledge from prior knowledge. It is also practical when it is impossible or very difficult to observe the causes of a phenomenon, but the consequences it produces.
Characteristics of the deductive method
Follow the direction from top to bottom, from the general to the particular. It is the method used in formal sciences. It is based on theory to predict observable phenomena through hypotheses. The conclusion is contained in the premises. If the premises are valid and true, the conclusion is also true. Their 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 occurs when thinking about living beings and their genetics. It is known that all living things have DNA (deoxyribonucleic acid). Therefore, if at any time a living organism is going to be analyzed, it follows beforehand that this organism will have DNA.
Validity and veracity in the deductive method
In the deductive method, erroneous conclusions can be made if the premises are not true. For example, considering the following premises:
Premise 1: All men are bad.
Premise 2: Your grandfather is a man.
Conclusion: Therefore, your grandfather is bad.
This argument it is validhowever, 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 bad”) 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 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 hypothetical-deductive method
The observation and analysis of a series of phenomena. It is proposed a hypothesis according to the results of what was observed in order to explain those 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. HE check the hypothesis from experiments. If the hypothesis is verified, then is accepted. If your assumptions are not verified, is rejected.
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