LogosGet the app

A free app for Android

Logic from the first question.

Start with intuition, then symbols. Logos teaches formal logic and the philosophy of logic from your very first question, all the way to a first university-course level.

Get it onGoogle PlayBy Cameron Train

How it teaches

Logos follows the same path a good teacher does: understand the idea first, then learn to write it down. Ordinary situations always come before P → Q.

  1. 1

    Intuition

    Every idea begins with an ordinary situation you already reason about — a promise, an accusation, a plan that falls through — long before any symbol appears.

  2. 2

    Interaction

    You test that intuition by doing: sorting cases, spotting where an argument breaks, and answering questions that push back until the idea holds.

  3. 3

    Formalization

    Only once the thinking is clear does the notation arrive. “If it rains, the match is off” becomes P → Q — a shorthand for something you already understand.

  4. 4

    Practice

    You return to each idea through graded exercises and proofs, building fluency until formal reasoning feels like second nature.

What's inside

Three ways in, one coherent whole — read, do, and play your way to real fluency.

The course

A structured path through formal logic.

From statements and truth to connectives, natural-deduction proofs, predicates, and quantifiers — the arc of a first university logic course, taught step by step.

Philosophy track

Why logic matters, not just how it works.

Read the questions behind the symbols: what makes an argument valid, what logic assumes, and where philosophers still disagree.

Endless puzzles

Practice that never runs out.

Freshly generated exercises keep you sharp, including Fallacy Spotter — a debate game where you catch the flaw in a real-sounding argument before the clock does.

Free to use. No ads, and your personal data is never sold.

Privacy Policy

This is the privacy policy for Logos, an Android app developed by Cameron Train. It explains what the app does and does not do with your information.

Last updated: August 2026

Using the app without an account
Logos works offline and signed-out. You can learn, practice, and play without creating an account or providing any personal information.
Optional account
If you choose to sign in, you can do so with an email address, a Google account, or a phone number. An account exists only to save and sync your progress — it is never required to use the app.
Progress & sync
When you are signed in, your learning progress is stored and synced using Google Firebase and Cloud Firestore so it is available across your devices. Signed out, your progress stays on your device.
Study reminders
You may optionally enable study reminders. These are local notifications scheduled on your device; enabling them is entirely your choice and they can be turned off at any time.
Crash reports
To keep the app stable, Logos uses Firebase Crashlytics to collect diagnostic crash reports. These help identify and fix problems and are not used to identify you.
On-device voice
Logos uses an on-device text-to-speech voice (Piper). The voice model may be downloaded once for offline use; after that, speech is generated locally on your device and voice data is not sent to a server.
Your controls
From the app's Settings you can reset your progress, delete local data, or delete your account. Deleting your account removes your synced progress associated with it.
No selling of personal data
Logos does not sell your personal data, and there are no advertisements in the app.
Children
Logos is intended for a general, adult-learner audience and is not directed at children.
Changes to this policy
If this policy changes, the updated version will be posted on this page with a new “last updated” date.
Contact
Add your preferred contact method here before publishing. Update CONTACT_EMAIL in lib/site.ts.