Logic basics: reasoning correctly

In short: Logic studies when something follows from statements. An argument is valid if the conclusion follows necessarily from the premises, and sound if in addition the premises are true.

In more detail: Classic example: All humans are mortal; Socrates is a human; therefore Socrates is mortal.

In detail

• Deduction: Compelling inference from the general to the particular.
• Induction: Generalising from observations, probable, not certain.
• Abduction: Looking for the best explanation of an observation.
• Propositional logic: Connections with AND, OR, NOT, IF-THEN.
• Truth tables: Check when compound statements are true.
• Valid ≠ true: A valid inference with false premises also leads to false results.
• Avoid mistakes: Know typical reasoning errors (trugschluesse-erkennen).
• Application: Programming, mathematics, discussions (was-ist-philosophie).