Mathematical Logic Explained

Mathematical Logic Explained
Mathematical Logic Explained | Ideasthesia

Logic is the study of what follows from what.

Given some premises, what can you legitimately conclude? Logic doesn't tell you whether your premises are true — that's the job of observation, experiment, or other domains. Logic tells you what's guaranteed to follow if your premises are true.

This is the machinery underneath all rigorous thought.

Every mathematical proof. Every legal argument. Every debugging session. Every time you say "if this, then that" — you're doing logic.


What You'll Learn

This series builds formal logic from the ground up:

Foundations:

  • What logic is and why it matters
  • Propositions and truth values
  • Logical connectives (and, or, not, if-then)

Propositional Logic:

  • Truth tables
  • Logical equivalence
  • Valid argument forms
  • Proof techniques

Predicate Logic:

  • Quantifiers (for all, there exists)
  • Variables and predicates
  • Translating English to symbols

Meta-Logic:

  • Soundness and completeness
  • The limits of formal systems
  • How logic connects to mathematics

The Series

What Is Mathematical Logic? The Science of Proof
Mathematical logic formalizes valid reasoning - turning arguments into algebra
Propositions and Truth Values: The Building Blocks of Logic
Propositions are statements that are true or false - the atoms of logical reasoning
Logical Connectives: And Or Not If-Then
Logical connectives combine propositions - conjunction disjunction negation implication
Truth Tables: Computing Logical Values
Truth tables show outputs for all input combinations - the multiplication tables of logic
Logical Equivalence: Different Statements Same Meaning
Logically equivalent statements have identical truth tables - different words same content
Tautologies and Contradictions: Always True and Never True
Tautologies are true regardless of inputs - contradictions are false regardless
Arguments and Validity: When Conclusions Follow
A valid argument has a conclusion that must be true if the premises are - form over content
Common Logical Fallacies: Where Reasoning Goes Wrong
Logical fallacies are invalid argument patterns that look convincing - learn to spot them
Quantifiers: For All and There Exists
Quantifiers express statements about all or some elements - ∀ and ∃ extend propositional logic
Methods of Proof: Direct Contradiction Induction
Different proof methods suit different problems - direct proof contradiction and induction
Mathematical Induction: Infinite Dominos
Mathematical induction proves infinitely many statements at once - if one domino falls they all fall
Synthesis: Logic as the Foundation of Mathematical Reasoning
Logic provides the rules by which mathematics operates - the operating system of proof

Why Logic Matters

Logic is the immune system of thought.

Bad arguments feel persuasive. Fallacies are common. Wishful thinking is natural. Logic provides tools to distinguish valid reasoning from sophisticated nonsense.

Logic makes invisible structure visible. When someone says "All politicians lie, and John is a politician, so John lies" — logic shows you the skeletal structure: All A are B, x is an A, therefore x is B. That structure is valid regardless of whether the premises are true.

Logic won't tell you what to believe. It tells you what you're committed to believing if you accept certain premises.


Prerequisites

This series assumes:

  • Basic comfort with mathematical notation
  • Willingness to think abstractly

No prior logic experience required. We'll build everything from scratch.


This is the hub page for the Logic series.

Next: What Is Mathematical Logic? The Science of Proof