Chapter 5

  • Indicator Words
    1. Some words indicate that what follows is a premise.
    2. Some words indicate that what follows is a conclusion.
    3. Remember, a conclusion might be either a sub-conclusion or the main conclusion.

  • Diagrams
    1. Number all statements.
    2. Find the conclusion.
    3. Find the statements the directly support the conclusion.
    4. Use an arrow to indicate therefore.
    5. Keep identifying supporting statements until all the original statements have been used.

  • Logical Strength
    1. We will distinguish between logical strength and factual strength.
    2. Factual strength indicates whether individual statements are true or false.
    3. Logical strength indicates whether premises support conclusions.
    4. Validity is another term for logical strength.
    5. Determining whether arguments are Valid or Invalid will be our primary task in this course.

  • Implicit Premises
    1. In many arguments, a statement is necessary for logical strength but not stated.
    2. Implicit (or implied) statements may be premises or conclusions.
    3. In diagrams, implicit premises are not numbered. We use letters, instead.

Indicator Words | Diagrams | Logical Strength | Implicit Premises | Question? | Self-test | Logic Page 1