4. Deduction and induction

  1. Deduction

   Reasoning make us to move from some truths to others , to move from known judgements to unknown judgements.

   Reasoning can be deductive and inductive. Deductive is the way that from a universal truth takes out a particular truth. Example all dogs are vertebrate then the dog I have is vertebrate.

  The inductive reasoning is the opposite to deductive reasoning: from the particular truths rise to a universal. Example: the science affirms the heat expands or make bulkier the copper, silver, iron, water, gases etc. In short words the heat expands all the bodies. The inductive reasoning moves from particular truths to the universal truth.

  A. Answer with one of these letters: a, b, c. (If the letter turns red the answer is right)

  1. Moving from some truths to others is

    a. concept
    b. judge
    c. reason

  2. Reasoning can be deductive and

    a. inductive
    b. scientific
    c. logical

 3. From the universal to particular is reasoning

    a. inductive
    b. deductive
    c. logical

 4. From the particular to universal is reasoning

    a. inductive
    b. deductive
    c. logical

 5. My dog is vertebrate by reasoning

    a. inductive
    b. deductive
    c. logical

 6. Heat expands bodies, by reasoning

    a. logical
    b. deductive
    c. inductive






  2. Complete and incomplete induction

   When it starts from the particular cases to get the universal truth then it is called complete induction.

   Example: we know that the three angles of an equilateral triangle are equal to one hundred and eighty degrees or two perpendicular lines. In the isosceles triangles are also equal to two perpendicular lines and in the scalene triangles are also equal to one hundred and eighty degrees. Therefore, we are sure that the angles of all the triangles are equal to two perpendicular lines. This is a complete induction.

   But in other occasions we can't verify all particular cases so the induction is incomplete.

   Example: We have notices that the copper is a good conductor of heat and the iron, silver and tin too. We can conclude that all the metals are good conductors of heat. But this induction is incomplete because we haven't noticed all the metals completely but only some of them.

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

  1. If it is verified all the particular cases, the induction is

    a. incomplete
    b. complete
    c. enough

  2. If it is verified some cases, the induction is

    a. incomplete
    b. complete
    c. enough

 3. In the complete induction we know

    a. some cases
    b. lots of cases
    c. all the cases

 4. In the incomplete induction we know

    a. some cases
    b. all the cases
    c. all the possible cases

 5. The example of triangles is induction

    a. incommplete
    b. complete
    c. enough

 6. The example of metals is induction

    a. enough
    b. complete
    c. incomplete


  3. Foundation of the induction

   The general truth of the incomplete induction is supported in a few particular truths.

   We know by the science a serie of facts showed many times.

   For Example: the heat expands the bodies; a body submerged in a liquid or a gas loses its weight, an equal part to the weight of the liquid that is expanded; a higher height less atmospheric pressure and the penicillin kills a serie of microbes.

   These are incomplete inductions but we say that they are established well enough and we have confidence in its truth because they have been checked many times.

   Sabemos que las mismas causas siempre producen los mismos efectos. We know that the same causes always produce the same effects. Thus, the laws of the Nature are universal and constant. This is the only guarantee, the only base of our scientific inductions.

   We have faith that the heat expands the bodies, the pressure goes down in the height, etc because we have faith in the order and constancy of the Nature.

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

  1. The science is supported in inductions

    a. incomplete
    b. complete
    c. sure

  2. In the sciences the truths have been showed

    a. few times
    b. some times
    c. many times

 3. The heat expands

    a. the spirits
    b. the bodies
    c. the height

 4. The scientific truths are established

    a. not well enough
    b. well enough
    c. few times

 5. In the scientific truths we have

    a. faith
    b. lack of faith
    c. doubts

 6. In the facts of the Nature we have faith in its

    a. disturbance
    b. inconstancy
    c. order and constancy




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| Educational applications | Philosophy |
For young |In Spanish | To print |

®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