A Deductive argument Is one that seeks to guarantee the validity of reasoning by pointing out that the conclusion reached is truthful because the premises (the arguments that precede the conclusion) are also true.
An argument in which the conclusion derives correctly from the premises is"deductively valid." If a valid argument has premises whose veracity can be confirmed, the argument will be solid. Let's look at this explanation with an example:
- Premise I: It's sunny in Singapore.
- Premise II: If it is sunny in Singapore, I will not wear umbrellas.
- Conclusion: then, I will not wear umbrellas.
The two premises guarantee the veracity of the conclusion, since this is the result of a logical reasoning. However, the argument has not presented information that allows us to establish whether the two premises are true, so it is not solid.
If one of the two premises is not true, this will not change the fact that it is a valid argument.
The arguments in logic were first studied by the Greek philosopher Aristotle . This established the difference between deductive and inductive arguments and, in this sense, indicated that deductive arguments are or are not valid, while inductives have degrees of acceptance, are likely or unlikely.
He also pointed out that, in deductive arguments, he believed that the veracity of the premises also ensured the veracity of the conclusion.
The typical pattern of deductive arguments is if A is B and B is C, then A is C. When the deductive argument follows this pattern, it is called"syllogism."
The syllogisms present two premises and a conclusion; The first premise is called the universal proposition and the second is known as a specific statement.
For example:
- Universal proposition: fish are not mammals.
- Specific statement: whales are mammals.
- Conclusion: whales are not fish.
However, not all arguments are presented in this way. For example, if we are told to be careful about ourselves Near the bees, because they can sting you. In this example it is understood that all bees sting.
25 Featured examples of deductive arguments
1 - Premise I: All men are mortal.
Premise II: Aristotle is a man.
Conclusion: Aristotle is mortal.
2 - Premise I: Donna is sick.
Premise II: If Donna is ill, she will not be able to attend today's meeting.
Conclusion: Donna will not be able to attend today's meeting.
3 - Premise I: A is equal to B.
Premise II: B equals C.
Conclusion: Then, A is equal to C.
4 - Premise I: Dolphins are mammals.
Premise II: Mammals have kidneys.
Bottom line: So all dolphins have kidneys.
5 - Premise I: All numbers ending in 0 or 5 are divisible by 5.
Premise II: 35 ends in 5.
Conclusion: 35 is divisible by 5.
6 - Premise I: To be able to graduate, students must have 32 credits approved.
Premise II: Mónica has 40 credits approved.
Conclusion: Mónica will graduate.
7 - Premise I: All birds have feathers.
Premise II: Nightingales are birds.
Conclusion: Nightingales have feathers.
8 - Premise I: All cats have a very developed sense of smell.
Premise II: Garfield is a cat.
Conclusion: Garfield has the sense of smell developed.
9 - Premise I: Reptiles are cold-blooded animals.
Premise II: Snakes are reptiles.
Conclusion: Snakes are cold-blooded.
10 - Premise I: Cacti are plants.
Premise II: Plants perform the photosynthesis process.
Conclusion: Cacti carry out photosynthesis.
11 - Premise I: Red meat is rich in iron.
Premise II: The steak is a red meat.
Conclusion: The steak contains iron.
12 - Premise I: The acute angles are smaller than 90 °.
Premise II: The angles of an equilateral triangle are 60 °.
Conclusion: The angles of the equilateral triangle are acute.
13 - Premise I: All noble gases are stable.
Premise II: Helium is a noble gas.
Conclusion: Helium is stable.
14 - Premise I: Magnolias are dicotyledons.
Premise II: Dicotyledons have seeds with two embryos.
Conclusion: Magnolias have seeds with two embryos.
15 - Premise I: All human beings are free.
Premise II: Ana is a human being.
Conclusion: Ana is free.
16 - Premise I: All cells contain deoxyribonucleic acid (DNA).
Premise II: Elephants have cells in their body.
Conclusion: Elephants have deoxyribonucleic acid (DNA).
17 - Premise I: It takes an hour to get to the mall from my house.
Premise II: I will leave my house at 5:00 PM.
Conclusion: I will arrive at the mall at 6:00 PM.
18 - Premise I: When my dog gets angry, it bites.
Premise II: My dog is angry.
Conclusion: My dog is going to bite me.
19 - Premise I: There are three people in my family.
Premise II: Each member of my family is tall.
Conclusion: All members of my family are tall.
20 - Premise I: Gravity attracts objects to the center of the planet Earth.
Premise II: Apples fall down.
Conclusion: Apples are attracted by gravity.
21 - Premise I: This dog always barks when someone is at the door.
Premise II: The dog has not barked.
Conclusion: Then there is no one at the door.
22 - Premise I: Sam is always where Ben is.
Premise II: Sam is in the library.
Conclusion: So Ben is also in the library.
23 - Premise I: Citrus fruits are rich in vitamin C.
Premise II: The lemon is a citrus.
Conclusion: Lemon is rich in vitamin C.
24 - Premise I: Sunday must not go to work.
Premise II: Today I must go to work.
Conclusion: So, today is not Sunday.
25 - Premise I: The planets are round.
Premise II: Earth is a planet.
Conclusion: The Earth is round.
References
1. Deductive and Inductive Arguments. Retrieved on May 31, 2017, from iep.utm.edu.
2. Deductive and Inductive Arguments: What's the Difference? (2017) Recovered on May 31, 2017, from thoughtco.com.
3. Definition and Examples of Deductive Arguments, Recovered on May 31, 2017, from thoughtco.com.
4. What is deductive argument? Retrieved on May 31, 2017, from whatis.techtarget.com.
5. Deductive and Inductive Arguments. Retrieved on May 31, 2017, from lanecc.edu.
6. Deductive Arguments and Valid Reasoning. Retrieved on May 31, 2017, from criticalthinkeracademy.com.
7. Deduction and Induction. Retrieved on May 31, 2017, from butte.edu.