# What Logic Actually Is

You reason all day. You decide a bug must be in the new code because it worked yesterday. You judge
whether a headline is fair. You write an `if` statement. Every one of those is *logic* - and almost
nobody was ever taught what it actually is, or how to tell good reasoning from reasoning that only
*sounds* good.

That gap is expensive. It's how smart people get talked into bad decisions, ship confident-but-wrong
code, and lose arguments they were actually right about. The good news: logic isn't a talent you're
born with or without. It's a small set of ideas you can learn - and once you have them, you can *see*
the structure underneath any claim instead of reacting to how convincing it feels.

This is the opening guide of the whole **Logic** track. It doesn't teach symbols or truth tables yet
(those come next). It installs the mental model everything else rests on: **logic is the study of what
follows from what.**

## How to read this
- **Want the big idea fast?** Read [Phase 1](01-logic-is-the-skill-under-everything.md) - it's the one
  reframe that makes the rest click.
- **Want it to genuinely stick?** Read all three in order; each builds on the last, and Phase 2 fixes
  the single confusion that trips up almost everyone.

## The phases
1. **[Logic Is the Skill Under Everything](01-logic-is-the-skill-under-everything.md)** - what logic
   *actually is*, why it's the foundation under code, math, and argument, and why it's worth your time.
2. **[Statements, Truth, and Validity](02-statements-truth-and-validity.md)** - the make-or-break
   distinction: a claim being *true* is not the same as an argument being *valid*. Get this and half of
   "logic" is already yours.
3. **[The Three Ways We Reason](03-the-three-ways-we-reason.md)** - deduction, induction, and
   abduction: the three engines of reasoning, what each guarantees, and where each quietly fails.

> This guide builds the foundation. The hands-on machinery - propositional logic, truth tables,
> if-then, quantifiers, proof, and spotting fallacies - lives in the guides that follow it. Its sister
> foundation is [Why Math Isn't Your Enemy](/guides/why-math-isnt-your-enemy).