Philosophy 207 Elementary Logic

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Philosophy 207Elementary Logic

• Prof. Kathleen Sauder
• Pontifical Catholic University of Puerto Rico

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Introduction

• What distinguishes man from all other animals?
• Only man can reason or think.
• But how does reasoning work? It is an operation
  which, like every other operation, can be done
  well or badly.
• If done well, we can know the truth about things.

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Division of the course

• Logic, the study of mans reasoning process, has
  three main parts, arrived at by considering the
  three operations of our intellect or reason
• 1. Simple apprehension, which involves our
  formation of concepts
• 2. Predication or judgment, which involves the
  combination of concepts
• 3. Reasoning itself, which involves seeing a
  relationship between two predications allowing us
  to arrive at new knowledge.

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The First Part of LogicFormation of
ConceptsLesson One

• In order to understand what a concept is, it will
  be useful to understand what a sign is, since
  concepts are a kind of sign.
• In general, a sign is something which, in
  addition to itself, represents or symbolizes
  something else to our minds.
• There are three kinds of signs
• Natural signs
• Conventional signs
• Formal signs

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• With all signs, there are three aspects to
  consider
• -The sign itself
• -The meaning of the sign
• -The connection between the two.

Sign
Meaning
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Natural Signs

• With natural signs, the connection between the
  sign and its meaning is established by nature.
  We cannot change the meaning of the sign.

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Meaning
Sign
Smoke
Fire
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Sign
Meaning
Snow
Cold
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Meaning
Sign
Downturned mouth, tear, facial expression
Sadness
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Sign
Meaning
Upturned mouth, facial expression
Happiness
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Sign
Meaning
Furrowed eyebrows, downturned mouth
Anger
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Sign
Meaning
High temperature
Illness
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Conventional Signs

• With conventional signs, the connection between
  the sign and its meaning is made up by human
  beings, and can therefore be changed by them if
  desired. There is no natural connection given by
  nature rather, an object is chosen and given an
  arbitrary meaning.
• Because of the creativity of the human mind,
  there is an enormous variety of conventional
  signs.

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Sign
Meaning
Stop
Red light
Prepare to stop
Yellow light
Go
Green light
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Sign
Meaning
An S with a vertical line through it
Dollar, money
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Sign
Meaning
Prayer
Folded hands
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Meaning
Sign
A cigarette surrounded by a red circle with
a diagonal line through it
No smoking
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Meaning
Sign
Stop your vehicle before proceeding with caution
A red, octagonal board with white letters
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Sign
Meaning
Outstretched hand
Stop
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Sign
Meaning
Clenched hand with thumb pointing up
Approval
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Sign
Meaning
Red circle with horizontal white line
Do not enter
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Sign
Meaning
Agreement, friendship, trust
Clasping hands
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Sign
Meaning
Blue person in wheelchair
Handicap access
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Sign
Meaning
Staff with two serpents entwined around it
The medical profession
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Meaning
Sign
Nuclear energy, radiation
Circle surrounded by three ellipses
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Formal Signs

• Formal signs, unlike natural or conventional
  signs, do not exist outside the mind.
• Our intellect uses concepts as signs of the
  natures of things that exist outside the mind.
  Our concepts signify or mean the things
  themselves.
• The imagination also creates formal signs, but
  these will not be studied in Logic.

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• Our concepts are truly signs because they mean
  something outside themselves.
• Concepts exist only within the intellect.
• Yet we all form the same concepts of things,
  which permits communication.
• In order to communicate what we are thinking
  about, we need to use external signs.
• This is what we do when we use words.

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Relationship between words, concepts, and things

• Words are verbal sounds. They also are signs,
  since they refer to something other than
  themselves. To what do they refer?
• Words are signs of our concepts.
• Our concepts are signs of things.
• Thus, the words we use do not directly mean the
  things, else it would be impossible to learn
  another language.

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• Horse, caballo, pferd, cheval, equus, hippos
• These words in different languages all mean the
  same thing the concept of horse.
• Words are signs, but what kind of signs?

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Sign
Meaning
The large animal with hooves and mane

Horse
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• Words are conventional signs. Signs of what?
• Signs of concepts.
• Concepts are formal signs. Signs of what?
• Signs of things.

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Conclusion, Lesson 1

• We perceive many things with our senses. Some
  things mean something else. Of the things that
  signify or mean something, we can distinguish
  various types
• - Natural signs
• - Conventional signs
• This helps us understand the kind of sign that
  cant be seen or felt the Formal Sign or concept.

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• All signs have in common that they point to
  something outside themselves.
• Intellectual knowledge is proper to human beings.
  In order to attain it, we need to ensure that we
  form adequate concepts of the things that exist
  outside our minds.
• The intellects first act, which we study in the
  first part of Logic, has to do with the formation
  of concepts.