- What Exactly is Metaphysical Possibility?
- Well-typedness & Carnap's 'Caesar is not a Prime Number' Problem
- Making sense of Falsifiability
- Possibility, Contingency, and a Modal Logic Problem
- A Cheap Linguistic Trick
- What Does it Mean for an Axiom to be Logical?
- On the Number of Empty Sets
- Logical Consequence vs Material Implication
- Statements vs Propositions
- Proving the Validity of Modus Tollens
- The Categorical Syllogistic as a Formal System
- Tensed vs Tenseless Propositions
- The Intuitionistic Notion of Falsity
- Prerequisites for Studying Modal Logic
- Proving that for all L ≤ S5, ◾◊φ ⊯ L Aφ.
- Dispelling a Semantical Confusion
- Semantic Brackets vs Corner Quotes
- Aristotle's Syllogistic and Proofs by Contradiction
- Reflexivity, Symmetry, and Transitivity
- Dispelling a Modal Confusion
- Contradiction vs Paradox
- Proof of (P ∨ (P ∧ Q)) ≡ P
- Is There a Hierarchy of Natural Laws?
- Concluding without Proving
- Functions vs Relations
- Aristotelian Said-of Predication
- Aristotle on Homonymy
- Syntactic vs Semantic Consequence & Soundness vs Completeness
- Proving that Apples aren't Oranges
- Chang & Keisler's Definition of Abstract Logics
- Free Variables
- Proofs of {G ∧ ¬H, ¬H → H} ⊢ (S ∧ I) and H ⊢ S → (B → H)
- Proofs of ¬(A ∨ B) ⊢ ¬(B ∨ A) and ¬(A ∨ ¬(A ∧ B)) ≡ ⊥
- The Syllogistic as a Special Case of Set Theory
- Defining n-ary Relations and Tuples
- Dispelling Another Modal Confusion
- An Appeal to Probability
- Object Language vs Metalanguage, & Metavariables
- Two Meanings of 'and'
- Positivism is Self-Defeating?
- Possible-Worlds Models
- Analyticity 1
- Analyticity 2
- Determining Truth-Functionality
- Dispelling a Confusion about Time
- Tautology, Logical Truth, Logical Consequence, & Logical Necessity
- Dispelling a Confusion about 'Nothing'
- Intensional Explication of Analyticity
- Valuation Functions
- Implication vs Entailment
- Conception vs Explication
- Philosophy as the Logic of Science
- The Logic of Nothingness
- The Rule of A-I Conversion
- The Definition of Logical Validity
- Proving that (φ → ◊φ) is Valid over Reflexive Frames
- Principles of Explosion
- Unrestricted vs Bounded Quantification
- The Monotonicity of Implication
- Fictional Quantifiers
- ¬—Eliem vs ⊥—Intro
- Dispelling a Confusion about Irrationality and Belief
- Dispelling a Confusion about Temporal Logic and Paraconsistency
- Can Every Proposition be Written in a Subject-Verb Form?
- Problems with Standard Deontic Logic