Premise

We explain what a premise is and its function in reasoning. Also, the types of premises and examples.

What is a premise?

In logic and philosophy, premises are called the initial propositions of an argumentfrom which it is possible to reach a conclusion. In all cases, the conclusion must be inferred or detached from the premises, through a deductive or inductive procedure that is valid and logical. For example:

Premise 1: The children went to school today.
Premise 2: Juan is a boy.
Conclusion: Juan went to school today.

The premises are the starting point of an argument (which allows you to demonstrate, justify or refute something). From the premises the inductive or deductive work begins. The same argument can have one or more premises and, since they are propositions, they always affirm or deny something and, therefore, can be true or false. For example:

In the Caribbean the climate is hot,
All the planets are round,
No pig can fly.

However, it is not the truth or falsity of the premises that determines whether the reasoning is valid or not, since False conclusions can be inferred from true premises.. The nature of the argument or reasoning and its validity depend on establishing a correct relationship between the premises and the conclusions, beyond the content. For example:

Premise 1: Matías visits us on Sundays
Premise 2: Today is Sunday.
Conclusion: Today Matías will visit us.

In this case, both premises can be true, but that does not mean that the conclusion must be true. Because Matías may not visit us that Sunday, even though he always does on Sundays.

The term “premise” comes from latin praemissus which means: “sent previously” and is made up of prae- (“before”) and missus (“send”), so it refers to that which is given in advance.

The study of premises dates back to classical antiquity, when the great Greek and Roman thinkers studied logic and oratory as forms of thought. This study generally took place around the syllogism: a type of reasoning in which given two premises, one general and one particular, a conclusion is obtained.

Premise types

According to the Greek philosopher Aristotle (384-322 BC) in his studies of the syllogism, there are two types of premises within this type of logical reasoning:

• The major premise. It is a premise that is usually of a general type, and contains the predicate of the conclusion. A general proposition is one that refers to a set or totality of certain things. For example: “All men are mortal.”
• The minor premise. It is a premise that is usually of a particular type, and contains the subject of the conclusion. A particular proposition is one that refers to a specific thing or subject. For example: “John is a man.”

The premises can also be classified according to the type of argument of which they are part:

• Premises of a deductive argument. In deductive arguments we move from the most general to the particular. The conclusion obtained is already contained in the premises. For example:Premise 1: Citrus fruits contain vitamin C.
  Premise 2: The orange is a citrus fruit.
  Conclusion: Orange contains vitamin C.
• Premises of an inductive argument. In inductive arguments, we start from the observation of the particular to make generalizations. For example: Premise 1: My cat loses hair
  Premise 2: My cousin's cat loses hair.
  Conclusion: All cats lose hair.

In addition, there are implicit premises, which are not mentioned because they are obvious or understood, as in the case of: “All human beings are mortal and Juan died yesterday”, in which it is not necessary to explain that Juan is a man.

Examples of premises

Some examples of premises are:

1. All birds have a beak.
   A chicken is a bird.
   All chickens have beaks.
2. No mammal can breathe underwater.
   Whales are mammals.
   No whale can breathe underwater.
3. The sun shines.
   The sun is a star.
   The stars shine.
4. First graders will finish classes tomorrow.
   José is in first grade.
   José will finish classes tomorrow.
5. In winter it is cold.
   It's cold today.
   We are in winter.
6. Julio Cortazar wrote Hopscotch.
   Julio Cortázar wrote “House taken”.
   Julio Cortázar was a writer.
7. All Mercosur countries are in South America.
   Paraguay is a member of Mercosur.
   Paraguay is in South America.
8. Eduardo is my mother's father.
   My mother's father is my grandfather.
   Eduardo is my grandfather.
9. The Chinese embassy is on this block.
   The Swedish embassy is on this block.
   The Spanish embassy is on this block.
   This is an embassy area.
10. My neighbor mows the lawn on Tuesdays.
    My neighbor is mowing the lawn.
    Today is Tuesday.
11. A yellow bus stopped at the corner.
    Another yellow bus stopped at the corner.
    The yellow bus must have a stop on the corner.
12. Leonardo da Vinci was a Renaissance painter
    Michelangelo was a Renaissance painter.
    Raphael was a Renaissance painter.
    The painters of the Renaissance are very recognized.
13. The black clouds anticipate a storm.
    There are black clouds.
    It will rain.
14. Ravioli is a type of pasta made from flour.
    Fusilli are a type of pasta made from flour.
    Spaghetti is a type of pasta made from flour.
    The pasta is made from flour.
15. Brazilians are soccer fans.
    Marcelo is Brazilian.
    Marcelo is a soccer fan.

Continue with: Deductive method

References

• “Premise” in RAE.
• “Syllogism” at the National Autonomous University of Mexico.
• “Logic II” at the University of Granada.