30 Examples of Logic

The logic is a philosophical discipline that studies the conditions of validity of statements and of the reasoning, the procedures of deduction, induction and demonstration and the criteria of truth and veracity.

In addition, logic is applied in different sciences to determine how the reasoning that allows building valid knowledge should be, since this discipline establishes if the arguments of one hypothesis are correct and whether an explanation of a phenomenon is relevant, that is, whether it is a logical consequence of the premises.

Next, each science is concerned with proving whether the hypothesis is true or probable (when checked with evidence using the scientific method) and if it is general (when it can be applied to similar phenomena, cases or facts).

There are also sciences that developed their own logics. For example, mathematical logic, which uses a symbolic language to study the validity of reasoning and propositions and which is used in mathematics and in other areas, and computational logic, which applies mathematical logic for the analysis and elaboration of computer languages ​​and the programming.

reasoning of logic

The arguments are arguments that are used with the aim of proving or refuting an idea and that are made up of:

Between the premises and the conclusion there is a relationship of inference, since a conclusion follows from one or several premises. There are different types of inference, but the most common are:

Logic states that a deductive reasoning is only sound or forceful when it is considered:

principles of logic

Aristotle, the Greek philosopher, described three principles that should guide the construction of all reasoning.

Logic Types

There are different branches of logic that are classified according to different criteria and that can acquire different names depending on the author.

Depending on your object of study:

According to the language you use, and its relationship with the validity and truthfulness:

logic examples

1. In symbolic logic, it is held that if one proposition (p) is true and another proposition (q) is true, the entire conjunction statement (p • q) is true.
2. In symbolic logic, it is held that if one of the two propositions is false, the entire conjunction statement is. So if p is true and q is false, then p • q is false.
3. According to symbolic logic, the negation (indicated by the symbol ˜) of a true statement (if p is true, then ˜p is false) and true the negation of a false statement (if q is false, then ˜q is real).
4. According to symbolic logic, an exclusive disjunction (p ⊕ q) is false if both statements, p and q, are true.
5. According to symbolic logic, an exclusive disjunction (p ⊕ q) is true if one of its statements is true and the other is false.
6. According to symbolic logic, an exclusive disjunction (p ⊕ q) is false if both statements, p and q, are false.
7. Deductive reasoning: All mammals take care of their young (premise 1), the dog is a mammal (premise 2); therefore, the dog takes care of its young (conclusion).
8. Deductive reasoning: All philosophers study existence (premise 1), Aristotle was a philosopher (premise 2); therefore, Aristotle studied existence (conclusion).
9. Deductive reasoning: All Van Gogh paintings are excellent (premise 1), “Sunflowers” ​​is a Van Gogh painting (premise 2); therefore, "The Sunflowers" is an excellent painting (conclusion).
10. Deductive reasoning: On sunny days the clothes dry faster (premise 1), today it is sunny (premise 2); therefore, the clothes will dry faster (conclusion).
11. Deductive reasoning: The gaseous planets have very dense atmospheres (premise 1), Jupiter is a gaseous planet (premise 2); therefore, Jupiter's atmosphere is very dense (conclusion).
12. Deductive reasoning: Felines have acute hearing (premise 1), the lion is a feline (premise 2); therefore, the lion has acute hearing (conclusion).
13. Deductive reasoning: All products in this store are of good quality (premise 1), this sofa is from this store (premise 2); therefore this sofa is of good quality (conclusion).
14. Deductive reasoning: The stars are constantly burning (premise 1), the Sun is a star (premise 2); therefore, the Sun is constantly burning (conclusion).
15. Deductive reasoning: Interval scales have relative zeros (premise 1), the Celsius degree system is an interval scale (premise 2); therefore, the Celsius degree system has relative zero (conclusion).
16. Deductive reasoning: Temperate forests have an average rainfall ranging between 600 mm and 1200 mm (premise 1), Canada's forests are temperate (premise 2); therefore, Canada's forests have a mean rainfall ranging from 600 mm to 1,200 mm (conclusion).
17. inductive reasoning: Planets have mass and gravitational force (premise 1), satellites have mass and gravitational force (premise 2); therefore, all bodies in space that have mass have gravitational force (conclusion).
18. inductive reasoning: Biology is a factual science and uses the scientific method to corroborate its hypotheses (premise 1), chemistry is a factual science and uses the scientific method to corroborate its hypotheses (premise 2), astronomy is a factual science and uses the scientific method to corroborate its hypotheses (premise 3); therefore, the factual sciences use the scientific method to corroborate their hypotheses (conclusion).
19. inductive reasoning: Pablo runs very fast and plays soccer well (premise 1), Renata runs very fast and plays soccer well (premise 2), Gabriela runs very fast and plays soccer well (premise 3); therefore, all people who run very fast play soccer well (conclusion).
20. inductive reasoning: My house has marble floors and is always cool (premise 1), my neighbor's house has marble floors and is always cool (premise 2); therefore, houses that have marble floors are always cool (conclusion).
21. inductive reasoning: Madrid is a big city and has many museums (premise 1), London is a very big city and has many museums (premise 2); therefore, in very large cities there are many museums (conclusion).
22. inductive reasoning: The pine is a tree and has green leaves (premise 1), the cypress is a tree and has green leaves (premise 2), the carob tree is a tree and has green leaves (premise 3); therefore, many trees have green leaves (conclusion).
23. inductive reasoning: Spinach is a green vegetable and has a lot of folic acid (premise 1), arugula is a green vegetable and it has a lot of folic acid (premise 2), the beet leaf is a green vegetable and it has a lot of folic acid (premise 3); therefore, green vegetables have a lot of folic acid (conclusion).
24. inductive reasoning: Black tea helps digestion (premise 1), green tea helps digestion (premise 2), red tea helps digestion (premise 3); therefore, teas aid digestion (conclusion).
25. inductive reasoning: On the beaches of Brazil the tide falls every 12 hours (premise 1), on the beaches of Italy the tide falls every 12 hours (premise 2), on the beaches of Thailand the tide falls every 12 hours (premise 3); therefore, in all the beaches the tide falls every 12 hours (conclusion).

Logic in everyday life

In everyday life, logic is used constantly, because speeches written or oral (such as conversations, journalistic notes, explanations or essays) usually include arguments to support ideas or opinions.

In addition, in different contexts of everyday life, the statements, whose connection of ideas is logical and valid, have greater acceptability than those that are inconsistent and wrong substantiated.

The term logic is also used to refer to the ways of acting or thinking that are most valued in a society. This type of logic is used by people to guide their behavior, as they carry out the actions that they believe are the best option in a given situation or at a given time.

Examples of logic in everyday life

1. If it rains and it is cold, it is convenient to go out with an umbrella; otherwise, a person may contract some disease.
2. It is always advisable to consult with a doctor before taking a medication; otherwise, a patient may worsen her health condition.
3. It is always preferable to take the shortest way to go to a place, because it will take less time to get there.
4. All the foods in this store are healthier, because they have a certificate that guarantees that they are organic.
5. It is easier to learn a second language that is similar to the mother tongue than one that is very different, because the structures and vocabulary are not so dissimilar.

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