We explain what deductive and inductive arguments are, how to differentiate them, their importance and examples of each one.
What are deductive and inductive arguments?
Deductive and inductive arguments are two ways in which logical reasoning can be presented.
Logic proceeds through arguments. These are made up of a series of premises from which a conclusion is derived. Depending on the relationship between the premises and its conclusion, we will be dealing with a deductive argument or an inductive argument.
- Deductive arguments. The truth of the premises makes the falsity of the conclusion impossible. These arguments are moved by consequence and logical necessity.
- Inductive arguments. The truth of the premises suggests or “induces” the truth of the conclusion. These arguments are moved by probability and custom, not by logical necessity.
In the case of deductive arguments, the validity of the argument depends on maintaining the truth of the premises in the conclusion. In your case, the results of inductive reasoning cannot be measured in terms of validity or invaliditysince they only affirm the probability of certain conclusions.
How to differentiate deductive and inductive arguments?
Deductive and inductive arguments are distinguished from each other according to their internal logic and the language used to formulate them. Its main differences are:
| Deductive arguments | Inductive arguments | |||
| They are based on logical bases, step by step. | They lack a logical basis, they are based on intuition and generalization. | |||
| They start from general premises and arrive at a specific conclusion. | They start from specific premises to formulate a general conclusion. | |||
| They aspire to be conclusive. | They aspire to a certain probability. | |||
| The relationship between its premises and its conclusions is one of necessity. | The relationship between its premises and its conclusions is one of probability. | |||
| The conclusions do not depend on any data that is not in the premises. | The conclusions depend on elements outside the reasoning. | |||
Examples of deductive arguments
- Premise: The planets are round.
Premise: The Earth is a planet.
Conclusion: The Earth is round. - Premise: Students who have missed the exam must take the retake.
Premise: Alfonsina is a student.
Premise: Alfonsina has missed the exam.
Conclusion: Alfonsina must submit the recovery. - Premise: Citrus fruits are a great source of vitamin C.
Premise: Lemon is a citrus fruit.
Conclusion: Lemon is a great source of vitamin C. - Premise: The zone basketball championship games are played on Sundays in February.
Premise: Today is Sunday, February 13.
Conclusion: Today a zonal basketball championship game will be played. - Premise: The winners of the contest must go on stage.
Premise: Marcelo won first prize in the contest.
Conclusion: Marcelo will have to go on stage. - Premise: The candidate must obtain more than 50% of the votes to be elected president.
Premise: The Young Front candidate obtained 23% of the votes.
Conclusion: The Young Front candidate was not elected president. - Premise: Jorge's children are my cousins.
Premise: Juan is Jorge's son.
Conclusion: Juan is my cousin. - Premise: On holidays the hair salon remains closed.
Premise: Today is a holiday.
Conclusion: The hair salon is closed. - Premise: The square root of prime numbers is an irrational number.
Premise: 7 is a prime number.
Conclusion: The square root of 7 is an irrational number. - Premise: All the teachers at the school attended the pedagogical day this morning.
Premise: Juliette is a school teacher.
Conclusion: Juliette attended the pedagogical day this morning. - Premise: Mammals reproduce sexually.
Premise: The lion is a mammal.
Conclusion: The lion reproduces sexually. - Premise: Water boils at 100°C.
Premise: The water in the kettle is boiling.
Conclusion: The water in the kettle is 100°C. - Premise: The band will give concerts this year in all the provinces of Argentina.
Premise: Neuquén is an Argentine province.
Conclusion: The band will give a concert in Neuquén this year. - Premise: All Zulema's daughters have brown eyes.
Premise: Nuria is Zulema's daughter.
Conclusion: Nuria has brown eyes.
Examples of inductive arguments
- Premise: Yesterday it rained in the City of Buenos Aires.
Premise: Today it is raining in the City of Buenos Aires.
Premise: Tomorrow rain is announced in the City of Buenos Aires.
Conclusion: In the City of Buenos Aires it rains a lot during spring. - Premise: The food at this Mexican restaurant is delicious.
Premise: The food at this Peruvian restaurant is delicious.
Premise: The food at this Venezuelan restaurant is delicious. - Premise: Mexican, Peruvian and Venezuelan food is Latin American food.
Conclusion: Latin American food is delicious. - Premise: The computer teacher is wearing a blue apron.
Premise: The literature teacher is wearing a blue apron.
Conclusion: All the teachers in this institution wear blue aprons. - Premise: My brother has a German Shepherd who loses a lot of hair.
Premise: My grandmother has a German shepherd who loses a lot of hair.
Conclusion: German Shepherd dogs lose a lot of hair. - Premise: At my neighborhood school they raise the flag every morning.
Premise: At the school on the corner they raise the flag every morning.
Conclusion: In schools they raise the flag every morning. - Premise: I found a typo in this book.
Premise: I found another typo in this book.
Conclusion: This book has many typos. - Premise: The water at Plage de Maui is crystal clear.
Premise: The water on Matira Beach is crystal clear.
Conclusion: All beaches in French Polynesia have crystal clear water. - Premise: The sports clothing store has discounts on its products.
Premise: The men's clothing store has discounts on its products.
Premise: The children's clothing store has discounts on its products.
Conclusion: There are many discounts in the stores on this street. - Premise: The cactus on my balcony is in bloom.
Premise: The neighbor's cactus is in bloom.
Conclusion: Cacti bloom during this time. - Premise: On Friday there was a lot of traffic on the highway.
Premise: Today is Friday and there is a lot of traffic on the highway.
Conclusion: On Fridays there is a lot of traffic on the highway. - Premise: Sonia's mobile phone was stolen on Domano Street.
Premise: Pastor's mobile phone was stolen on Domano Street.
Conclusion: There are many robberies on Domano Street. - Premise: They suspended the flight to Lima this morning.
Premise: They suspended the flight to Lima this afternoon.
Conclusion: My flight to Lima tonight is likely to be cancelled. - Premise: My cat meows.
Premise: My cousin's cat meows.
Conclusion: All cats meow.
Importance of deductive and inductive arguments
Both deductive and inductive arguments are ways of generating information about the world. These two types of reasoning are used constantly on a daily basis to explain or learn new information.
- The deductive arguments. They are important when drawing conclusions based on the information you have. That is why they are considered explanatory, because they do not generate new information, but rather verify existing information. If the premises are correct, the deductive argument will always allow us to reach a correct conclusion.
- Inductive arguments. They are used to make generalizations based on certain premises. This type of reasoning is important because it allows us to obtain information from something that is observed. It must be taken into account that inductive arguments are based on probability, so they cannot always be verified, and their conclusions are considered probable, not certain.
Continue with: Argumentation
References
- “Deductive reasoning” on Wikipedia.
- “Inductive reasoning” on Wikipedia.
- “Difference between deductive and inductive reasoning” (video) on Khan Academy.
- “On classification of arguments and defeatability” by Damián Olivares Stagnaro in Philosophy Pages of the National University of Comahue (Argentina).
- “Induction and deduction” in Filosofía.org.
