In formal logic, we develop different systems of symbols and rules to express ideas and carry out proofs. There are lots of such formal systems. In this module we discuss Sentential Logic (SL). It is one of the simplest formal systems of logic, and is also known as "Propositional Logic".

Before you begin, p check that your browser can display the logic symbols used in this module. These are the symbols:

≡ ∨ ↔ → ∃ ∀ ψ φ α β ⊧

They should look like the ones in this picture:

If not, try a more advanced browser, such as Chrome.

- [SL01] Introduction
- [SL02] Well-formed formula
- [SL03] Connectives
- [SL04] Complex truth-tables
- [SL05] Properties & relations
- [SL06] Formalization
- [SL07] Validity
- [SL08] The indirect method
- [SL09] Indirect method: exercises
- [SL10] Material conditional
- [SL11] Derivations
- [SL12] Derivation rules 1
- [SL13] Derivation rules 2
- [SL14] List of derivation rules
- [SL15] Derivation strategies
- [SL16] Soundness
- [SL17] Completeness
- [SL18] Limitations

After you have finished this module, try our next module on predicate logic!

- A very good informal introduction: Graham Priest - Logic: A Very Short Introduction
- An introduction to formal logic. Used to be the standard textbook for first year logic students at Oxford: Wilfrid Hodges - Logic
- Harry Gensler - Introduction to Logic
- Very advanced: George Boolos - Computability and Logic
- Many advanced topics included: Theodore Sider - Logic for Philosophy
- A good textbook on formal logic that is available free online: http://tellerprimer.ucdavis.edu
- A good logic self-study guide (PDF): Teach Yourself Logic 2017: A Study Guide
- Entries on logic in the Stanford Encyclopedia of Philosophy - These are articles that discuss some of the main issues in the philosophy of logic. They are difficult!