What is deduction?
Deduction is a logically correct conclusion from already existing knowledge or from already existing thoughts. Conclusions built with the help of deduction are studied by the science of logic. Natural deduction in logic uses rules that are close to the way a person reasoned, therefore it is called "natural deduction". Deduction is used in everyday life as well as in teaching and analytical work.
An example of deductive reasoning in logic
Deduction has been known since the time of Aristotle. It was Aristotle who considered inferences with premises and conclusions.
An example of deductive inference:
All people are mortal.
Socrates is a man.
Consequently, Socrates is mortal.
The first two judgments are called premises, and the last judgment is a conclusion or consequence.
In logic, there are certain rules of inference on the basis of which reasoning is built. These rules are needed in order to come to a true conclusion based on true premises.
Applying deductive reasoning to everyday life
In Conan Doyle's stories, the famous detective Sherlock Holmes talks about his deductive method. Indeed, he looks at the general picture of the crime, then examines the details. Deduction is reasoning from general knowledge to particular knowledge. That is, if we already have some initial knowledge, then in the process of reasoning we come to certain conclusions.
Imagine how the detective would reason. Let's say we are outside the city and see a man carrying a fish.
Initial knowledge - a person carries a fish. Further, our reasoning looks like this. We can assume that, first, a person bought this fish in a store. But there is no store nearby, so most likely he took the fish from someone or caught it himself. If a person caught the fish himself, then he should have fishing rods with him. But he has no fishing rod. Then, perhaps, the fishing rod remained on the shore, or he did not have a rod at all. If this person does not have a fishing rod at all, then he took the fish from someone. It will be enough for the detective to see if there is a fishing rod on the shore. If it is, then this person caught the fish himself. If it is not there, then the person took this fish from someone.
This is an example of deductive reasoning: there is an initial common knowledge, and further we consider particulars and details.
An example of deductive reasoning when making a decision
Andrey's level of English is now slightly below average. He wants to reach Intermediate English (B1) in 3 months. Consider Andrey's reasoning.
If I study on my own, then I will need to look for teaching materials, exercises and complete assignments myself without checking the teacher. Then I will have to plan 3 hours a day for English classes in order to reach B1 level in 3 months.
If I study with a teacher 2 times a week, then I do not need to look for teaching materials, exercises, and the teacher will check my assignments. In this case, I have to plan 2 hours a day for English classes in order to reach B1 level in 3 months.
Study on your own or study with a teacher
Study on your own
Schedule 3 hours of English classes per day.
I will reach B1 level in 3 months.
Study with a tutor
Schedule 2 hours a day for English classes.
I will reach B1 level in 3 months.
I will reach B1 level in 3 months.
How does the deductive method help in life?
- The goal is determined in advance.
- We are considering options for how you can achieve it.
- Decision making is not influenced by emotion.
- The decision is not influenced by the advice of third parties.
- You yourself choose the direction that will allow you to reach your goal.
- You can choose the most economical (in terms of money or time-consuming) solution.
Application of the deductive method in teaching and analytical work
The deductive method of teaching is based on explanation using rules. First, there is a presentation of the rules, and then examples of the use of these rules and exercises to practice them follow.
An example of deductive learning might be the following situation:
You get a new job. On the first working day, you noticed that your new colleagues put a plus sign in front of their name at the entrance to the building, take a pass, and after a working day give them a pass at the exit from the building. Then you do the same.
So, using the deductive method, you initially rely on some rule. For example, in the work of a teacher of foreign languages, the application of this method will be as follows.
When a lesson on grammar begins, after some introduction, a greeting, the teacher first explains the rule for using a particular grammatical structure, then gives examples of use, and gives students exercises on how to apply this rule.
Application of the deductive method in cognitive-behavioral psychology
Consider an example of the application of the deductive method in cognitive-behavioral psychology. The work of a psychotherapist is analytical, a specialist analyzes the client's thought process, draws conclusions. It should be noted that the peculiarity of this therapy is that the client does a lot of independent work, reads literature and practices skills.
When a client comes to the first session with a psychotherapist, he is not aware of the essence and characteristics of consultations with a psychotherapist working in this direction. The psychotherapist first explains the specifics of cognitive-behavioral therapy, tells how beliefs affect emotions, and then the therapist sets the task for the application and development of certain rules for identifying cognitive distortions.
Of course, both teachers and psychotherapists use different methods in their work. Each method has its own characteristics, advantages and disadvantages. I emphasize once again that in this article I am considering the techniques and methods of the deductive method.
An overview of the deductive approach in teaching and analytical work would be incomplete without considering some of the shortcomings of the method.
Disadvantages of a deductive approach
Let's consider an example of using this method in teaching a foreign language.
- Starting a lesson with a grammar presentation can be time consuming and challenging for some students, especially beginners. They may not know specific terminology to explain grammar. In addition, they may not understand some of the simpler grammatical constructions.
- Explaining grammar shifts the focus to the teacher, thereby reducing the amount of time that can be spent interacting with each other. Thus, most of the lesson time is not devoted to practicing communication skills and using language in speech.
- Explanation is not as well understood as other forms of presentation, such as visual demonstration.
- This approach can lead the student to believe that knowledge of a language is simply knowledge of a certain set of rules.
The deductive method has many advantages, let's look at some of them.
Benefits of the deductive method
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Literature:
Thornbury S. How to Teach Grammar. Pearson Education Limited, 1999
Johan van Benthem, Hans van Ditmarsch, Jan van Eijck, Jan Jaspars. Logic in Action, 2016
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