Thinking rationally: "laws of thought"

Aristotle: what are correct arguments - Yield correct conclusions when given correct premises
Several Greek schools developed various forms of logic: notation and rules of derivation
Direct line through mathematics and philosophy to modern AI: logicist tradition

1965 – programs that could, in principle, solve any solvable problem described in logic notation


Problems:
Not easy to take informal knowledge and state it in formal terms (particularly uncertain knowledge)
Solvable in principle <> practically solvable
Not all intelligent behavior is mediated by logical deliberation
What is the purpose of thinking? What thoughts should I have?