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What is logic?

The study of the principles and methods used to distinguish good (permissible, correct) reasoning from bad (impermissible, incorrect) reasoning.


What is the difference between descriptive and normative disciplines?

  1. Descriptive tells you how things were, are and will be
  2. Normative tells you how things ought to be, should be or must be (permissible/impermissible)


What is critical thinking?

  • purposeful, reflective, mental activity directed at ASKING QUESTIONS and SOLVING PROBLEMS.


What are some examples of critical thinking questions?

  • What would happen if I do x ?

  • What should we do? Why?

  • What do you mean?

  • Why do you believe that?

  • Is what you believe more reasonable than what I believe?

  • By saying x , aren't you assuming y?

  • If you assume x , then doesn't follow y?

  • Can you show me that what you say is true?

  • Can you prove it?


What is an argument?

  • a set of statements where the truth of one is supposed to follow from the other(s)
  • Good arguments are the medium through which we plan, explain, persuade, convince, show, demonstrate, and prove things successfully through language.


What are the two parts of every argument?

  • premises (or evidence)

    • the reasons or assumptions offered to show that the conclusion is true

  • conclusion (or claim)

    • the single statement asserted to be true on the basis of the evidence


What does the symbol ∴ means?

It is read "therefore"


What is the difference between a valid and an invalid argument?

  • Whenever it is impossible for a claim to be false when its evidence is true, the argument is valid.

  • Whenever it is possible for a claim to be false when its evidence is true, the argument is invalid.


What is a sound argument?

  • a valid argument with true premises


What is the hard part of offering good premises?

  • offering evidence whose collective truth shows that a claim is true.


What is the difference between natural and formal languages?

  • Natural = Spanish, German, English
  • Formal = “artificial” (symbolic) languages


What is the importance of languages in logic?

  • The language required to use the methods of a logic determines whether that logic is informal or formal, and if the latter, what type.
    • Informal logic requires using a natural language.

    • Formal logic requires using an artificial one.


What is the RIFUT rule?

  • The basis of our procedure for evaluating whether an argument is good in the fullest sense of the word.

  • Relevant to the claim logically,
  • Independent of the claim,
  • Free of dubious assumptions,
  • Unambiguous, and
  • True.


What is a cogent as opposed to a fallacious argument?

  • cogent = an argument is good in the fullest sense of the word

  • fallacious = an argument that commits an error in reasoning.


What is sentential logic?

  • Artificial language where capital letters take the place of atomic statements


What are deductive arguments?

  • its conclusion “follows necessarily” from its evidence if and only if the argument is valid.
    • There is a necessary connection between the truth of the evidence and the truth of the claim.


What is deductive logic?

  • Study of principles and methods used to distinguish good deductive reasoning from bad deductive reasoning. This may be done informally or formally.

  • classical logic, sentential logic, and predicate logic are formal deductive logics.


What is an inductive argument?

  • its conclusion follows from its evidence just in case the evidence makes the conclusion more likely to be true than not.

  • It does not "follow necessarily"

  • Such arguments are deemed as "strong." If an inductive argument is not strong, it is weak.


What is the problem of induction?

  • no accumulation of evidence and no amount of experience will ever — EVER — guarantee that events in the future will unfold as they did in the past


What is formal logic?

  • symbolic study of the principles and methods used to distinguish good reasoning from bad reasoning


What is formal system?

  • a formal language together with its logical principles and methods


What is inductive logic?

  • the study of principles and methods used to distinguish good inductive reasoning from bad inductive reasoning


What is unreasonable?

  • something that violates good reasoning or judgment