2. The concept

  1. What is a concept?

   Logic studies concepts, judgments and reasoning.

   A concept is the mental representation of an object. It is the simple capture of the essence of an object, but without affirming or denying anything. For instance, the ideas of a table, a pen, a computer and a blackboard are concepts.

   There are two types of knowledge: the sensitive and the rational one.

   The sensitive knowledge is acquired by means of senses (sight, hearing, etc.) and understands what is concrete and particular. For instance, I can see this pen, with this colour, size and special shape.

   The rational knowledge is acquired by means of reason and understands what is abstract and essential. I have the general idea about what a pen is: an instrument to write.

   Let us remember this sentence: There is nothing in mind that there has not been in senses before. Firstly we perceive things through senses and after we form an idea or rational knowledge.

   The concept is the abstract idea (rational knowledge) based in sensitive knowledge.

  A. Choose the right letter: a, b, c. (If the letter turns up red the answer is correct)

  1. Logic studies concepts, judgments and

    a. perceptions
    b. reasonings
    c. knowledge

  2. Mental representation is

    a. the concept
    b. the judgment
    c. the reasoning

 3. Knowledge can be sensitive and

    a. rational
    b. perceptive
    c. by heart

 4. What type of knowledge is acquired by means of senses?

    a. rational
    b. perceptive
    c. sensitive

 5. What type of knowledge is acquired by means of reason?

    a. sensitive
    b. rational
    c. perceptive

 6. An abstract idea is

    a. a sensitive knowledge
    b. a judgment
    c. a concept

  2. Concept, word and object

   A concept is an idea in my mind. For example, the idea of a pen.

   A word is a voice that expresses some idea. For instance, the word “pen”.

   An object is the thing I know. For example, the thing I write with.

   The same idea can be expressed with different words. For instance, man, rational animal, homme, etc.

   About the same object or thing we can have different ideas.

   The concept’s object is not always of a material nature (table, pen, computer) but it can be immaterial or a general idea (justice, honesty, friendship, etc.). In order to form these concepts our mind makes use of senses and imagination: we connect the ideas between each other and compare the tangible with the intangible.

   The concept has two logic proprieties: comprehension and extension.

   Comprehension is its content, the group of notes that defines it.

   Extension is the group of objects the concept is referred with. For instance, the comprehension of the concept “man” is “rational animal” (the concept “man” incorporates the notes “animal” and “rational”). The extension is the whole group of rational beings, the group of all men (American, European, Asian, etc.).

  B. Answer with one of these letters: a, b, c.

  1. The idea in my mind is

    a. the word
    b. the object
    c. the concept

  2. The voice I express the idea with is

    a. the object
    b. the concept
    c. the word

 3. The thing I know is

    a. the object
    b. the concept
    c. the word

 4. Justice and friendship are concepts

    a. tangible
    b. intangible
    c. liquid

 5. What sort of concept’s objects are a pen and a computer?

    a. tangible
    b. intangible
    c. gaseous

 6. An object has two proprieties, comprehension and

    a. tangible
    b. extension
    c. intangible

  3. The Logical Tree

   We can derive concepts less ample from a broad concept. The comprehension is growing and the extension decreasing. For instance, from a tree’s trunk branches emerge, and from these branches emerge another more little ones, until we reach leaves, flowers and fruits.

   Another example from Geometry: Figure: flat and with volume Flat: polygon, circle, ellipse Polygon: triangle, quadrilateral, pentagon Triangle: equilateral, isosceles, scalene

   From this Logical Tree, the equilateral triangle is a polygon and a flat figure.

   The concept of a polygon is subordinate to that of a flat figure and the concept of a triangle is subordinate to that of a polygon.

   On the other hand, concepts as polygon, circle and ellipse are called coordinate between each other, because all of them derive from the flat figure.

   Neoplatonic philosopher Porfirio lived between the years of 232 and 304, and made the famous Porfirio’s tree, as showed in the picture over. He makes a complete division of the real substantive being, object, living being, animal, man, before we achieve the individual Peter.

  C. Choose the right letter: a, b, c.

  1. We start from a broad concept to another

    a. less ample
    b. coordinated
    c. subordinate

  2. In the example of the tree we start from

    a. branches
    b. trunk
    c. leaves

 3. In the example of Geometry, the boarder concept is

    a. flat
    b. figure
    c. polygon

 4. The concept of triangle is subordinate to

    a. figure
    b. flat
    c. polygon

 5. The concepts triangle, quadrilateral and pentagon are

    a. coordinated
    b. subordinate
    c. equivalents

 6. Porfirio was a

    a. sophist
    b. demagogue
    c. philosopher

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®Arturo Ramo García.-Record of intellectual property of Teruel (Spain) No 141, of 29-IX-1999
Plaza Playa de Aro, 3, 1º DO 44002-TERUEL