The difference between the inductive and deductive method lies in the direction of the reasoning to reach conclusions.
Both inductive and deductive methods are logical reasoning strategies, and inductive uses particular premises to reach a general conclusion, and deductive uses general principles to reach a specific conclusion.
Both methods are important in the production of knowledge. During a scientific investigation, one or the other, or a combination of both, may be used, depending on the field of study in which it is conducted.
Currently, the method used in the experimental sciences is the so-called hypothetical-deductive method.
|Inductive method||Deductive method|
|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 starting from general laws or theories towards particular cases.|
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. It is currently used as part of the scientific method in general.
|Formal sciences such as mathematics and logic.|
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, as it consists in the collection of data on specific cases and their analysis to create theories or hypotheses.
Characteristics of the inductive method
- Follow the direction from bottom to top, from the particular to the general.
- It starts from empirical observations and then builds theories on what is observed.
- It is still used in the sciences, but within the hypothetico-deductive method.
- It is limited to the observation of phenomena.
- Conclusions are probable and may turn out to be false.
The observation of the inductive method
Observation is one of the key aspects of the inductive method. The experience of phenomena is important in scientific areas where data is collected from facts and observed phenomena, to arrive at a general hypothesis or theory.
For scientific knowledge to carry weight, it is important that numerous observations are made about a fact so that, if similar conditions are present, a generalization can be made.
In addition to observation, the inductive method uses experimentation to obtain the necessary data that lead to the formulation 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 there.
- 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, add the internal angles of a triangle and note that they add up to 180 degrees. 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 put together, he comes to the general conclusion that the interior angles of a triangle add up to 180º. In other words, based on this series of observations and the comparison, it is concluded that this will continue to happen.
Another example is when it is observed that all objects that rise tend to fall. If a series of objects is picked up and then dropped, each is observed to fall towards the floor. This leads to the conclusion that there must be some property or force that causes objects to attract each other (in this case the mass of each object).
It was so that, through this type of observations, it was established law of gravity, formulated by the English naturalist physicist Isaac Newton (1643-1727). This law basically proposes that all bodies with mass attract each other. This was how Newton verified it through several observations. It can be said, therefore, that “everything that goes up must come down”.
Limitations of the inductive method
Science is constantly developing. Despite having general laws that predict events or phenomena, those involved in science know that there may be cases in which conclusions do not apply.
This is why the inductive method as such can be insufficient when it comes to building knowledge and expanding 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 that it is not always possible to establish a universal truth, starting from particular observations. For Popper, the most important thing is to find facts that can falsify (refute) conclusions in the sciences.
A famous example is that of affirmation “all swans are white”. At some point in Europe this was believed to be the case. It was observed that the swans were characterized as 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.
You may also be interested in seeing Objective and subjective.
The deductive method is a type of reasoning used by 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 applying laws to particular phenomena that are 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 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 the formal sciences.
- It relies on theory to predict observable phenomena through hypotheses.
- The conclusion is contained in the premises.
- If the premises are valid and true, so is the conclusion.
- 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: So Socrates is mortal.
It is possible to observe that the conclusion is already implicit in the premises.
Another example occurs when you think about living things and their genetics. All living things are known to have DNA (deoxyribonucleic acid). Therefore, if any living organism is ever to be analyzed, it is a foregone conclusion that that organism will have DNA.
Validity and veracity in the deductive method
In the deductive method, erroneous conclusions can be drawn 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: So your grandfather is bad.
This argument is validBut, it 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 truth does not follow from the premises, so it still needs to be verified.
In this sense, the conclusions of the deductive method are valid and correct when the premises are also valid. Likewise, if the premises are true, so will the conclusion.
The method currently used in scientific research is the so-called hypothetical-deductive method. This method basically synthesizes the main aspects of the inductive and deductive method.
Steps of the hypothetico-deductive method
- The observation and analysis of a series of phenomena.
- One is proposed hypothesis according to the results of what was observed to explain these phenomena. For the hypothesis to be valid, it must be possible to test it.
- When a hypothesis postulates something, it is deduce that if the same conditions that caused a phenomenon are present, the consequences that the hypothesis predicts should occur.
- Is check the hypothesis from experiments.
- If the hypothesis is verified, then is accepted. If your assumptions are not verified, is rejected.
You may be interested in reading: