Formulas & shortcuts
Philosophy · 13
Every formula in this course and the easiest ways to remember them, on one page.
1Thinking philosophicallyAdvanced
What is philosophy? Its branches and questions
Open lessonLogic and critical thinking
Open lesson- P → Q“if P, then Q” (implication)
- ¬Q → ¬Pthe contrapositive: “if not Q, then not P”
- ≡equivalence: both statements always have the same truth value
Modus tollens rests on exactly this. Careful: Q → P (the converse) and ¬P → ¬Q (the inverse) are different statements.
2The history of philosophyAdvanced
Ancient philosophy: Socrates, Plato, Aristotle
Open lessonPhilosophy in the Islamic world and the East
Open lessonModern philosophy: Descartes, Locke, Hume, Kant
Open lesson3Ethics, mind and societyUniversity
Ethics: virtue, duty and consequences
Open lesson- U(A)total utility of action A (in notional wellbeing units)
- uᵢchange in the wellbeing of person i (+ or −)
- pⱼprobability of outcome j (Σ pⱼ = 1)
- Uⱼtotal utility if outcome j happens
Where it comes from: the principle “everyone counts as one” means adding up each person's wellbeing with equal weight. When the outcome is uncertain, each scenario's utility is multiplied by its probability and the results are added — expected utility.
Philosophy of mind and science: mind and body, Popper, Kuhn
Open lesson- Tthe theory being tested (together with auxiliary assumptions)
- Othe prediction (observation) derived from the theory
- ⊢“it follows logically”
Popper's asymmetry uses the forms from the logic lesson: if the prediction comes true, T is not proven (that would be affirming the consequent); if it fails, T is refuted by modus tollens.
Political philosophy: the social contract and justice
Open lesson- Athe society (distribution option) being compared
- xᵢ(A)the wellbeing index of group i in society A (for example, an income index)
- nnumber of equal-sized groups
Where it comes from: behind the veil you could end up in any position. When life's basic prospects are at stake, it is reasonable to choose the option that makes the worst position as good as possible (maximin). A utilitarian instead maximises average (or total) wellbeing.