Logic 1.3

Deduction and Induction

•Deductive Arguments: it is impossible for the conclusion to follow from the premises, be false and the premises to be true. The conclusion follows necessarily from the premises. (Possible worlds and counter-examples)

•Inductive Arguments: it is improbable that the conclusion be false given that the premises are true. The conclusion follows probably from the premises. (What is the nature of, and problems with, probability?)
Exs.

The difference lies in the strength of the inferential claim. Interpretation is required.
•Special indicators (probably, necessarily, etc.)
•The actual strength of the inferential link (possible worlds, counter-examples)
•The form or style of argument

Deductive Forms (analyticity)
• Mathematics
• Definitions
• Categorical Syllogisms (all, no, some)
• Hypothetical Syllogisms (if…then)
• Disjunctive Syllogisms (either…or)

Inductive Forms (goes beyond available content)
• Predictions
• Analogy
• Generalization
• Authority
• Signs
• Causal Inference (from cause to effect, Hume or Kant)


Generally, deductive arguments move from a position greater to or equal to their conclusions. Inductive arguments move from a position inferior to their conclusions. Exceptions occur, and these generally reveal problems for logic, most particularly induction. (Grue)