The deduction follows one of the methods of reasoning used during the scientific process to reach a logical and true conclusion.
It is used to test hypotheses and theories. Deductive reasoning, or deduction, begins with a general truth that applies to a specific case, and from these two pieces of evidence (premises), a specific conclusion about the specific case is drawn.
For its part, the other logic system for solving problems is induction. In this case, a generalization, conclusion, or inference is reached from a set or group of observations.
Deductive reasoning
In this type of reasoning, the argument contains one or more premises and at least one conclusion. The premises are propositions or statements that serve as reasons in an argument.
On the other hand, the conclusion is also the proposition or statement that the argument is supporting. Both the premises and the conclusions are statements that can be true or false.
One of the classic examples of deduction is the syllogism:
All men are mortal; Pedro is a man; therefore, Peter is mortal.
In this example you can see the difference between premises and conclusion:
First premise (general): All men are mortal.
Second premise (specific): Pedro is a man.
Conclusion (specific): Peter is mortal.
Deduction examples
The following deduction examples illustrate this method of reasoning:
1-Every Sunday there is at least one mass in the parish. Today it is Sunday. There will be at least one mass in the parish.
2-Living bird species have feathers. My canary is a kind of bird. My canary has feathers.
3-Whenever it rains, Carlos takes out his yellow umbrella. It's raining. So, Carlos took out his yellow umbrella.
4-Arab women wear an abaya when they are out in public. Khayla is Arab and is a woman. She is out and about in public. Therefore, Khayla is wearing an abaya.
5-Mr. González's assistant accompanies him on all his business trips. Mr. González is on a business trip. Mr. González's assistant is accompanying him.
6-All modern buildings in that city have an anti-seismic system. The building on that corner is modern. Therefore, the building on the corner has an anti-seismic system.
7-Without exception, candidates for governor must make a declaration of assets. You are a candidate for governor. You must make a declaration of assets.
8-Reptiles have cold blood. Crocodiles are reptiles. So, crocodiles are cold-blooded.
9-To be worthy of this award, doctors must have saved at least three lives a week. Paula's doctor, Dr. Juan, has saved five lives a week. Juan is worthy of that award.
10-The students who attend that university are Catholics. Roberto graduated from that university. Consequently, Roberto is a Catholic.
11-Human bones grow until people reach puberty. Carmen is 25 years old. Carmen's bones don't grow anymore.
12-Poisonous mushrooms can cause gastric disorders. Anita ate poisonous mushrooms. Anita will surely have gastric disorders.
References
- Bradford, A. (2017, July 24). Deductive Reasoning vs. Inductive Reasoning. In Live Science. Retrieved on October 13, 2017, from livescience.com.
- Induction vs. Deduction (s / f). Montana State University. Retrieved on October 13, 2017, from msubillings.edu.
- Rothchild, I. (2006). Induction, deduction, and the scientific method, an eclectic overview of the practice of science. Retrieved on October 13, 2017, from ssr.org.
- Rainbolt, GW and Dwyer, SL (2014). Critical Thinking: The Art of Argument
Connecticut: Cengage Learning.
- Dowden, BH (2017, October 4). Logical Reasoning. California State University Sacramento. Retrieved on October 13, 2017, from csus.edu.
- Carr, P. (2009). Deduction / induction. In S. Chapman and C. Routledge (editors), Key Ideas in Linguistics and the Philosophy of Language, pp 47-54. Edinburgh: Edinburgh University Press.