Symbols vs Liminal

Learn logic with Symbols, the app that teaches natural deduction and the rules of inference in an intuitive, accessible way. Our unique Studycards feature visual pictographs and interactive, step-by-step exercises that allow you to grasp each rule easily and quickly. Then, challenge yourself with activities specifically designed to practice those rules, building your skills progressively, and cementing them in your memory with every level completed. Why Symbols? Comprehensive Studycards: Learn essential rules like Modus Ponens, Modus Tollens, Disjunctive Syllogism, and many more through clear explanations and examples. Perfect for students and anyone looking to understand formal logic. Engaging Activities for Skill Mastery: Validity: Sharpen your critical thinking by evaluating pre-solved arguments. This unique activity provides the benefits of repetition without the tedium, helping you apply, recognize, and grow familiar with the rules of inference. Justification: Challenge your understanding with puzzle-like scenarios where you deduce missing argument steps. This deepens your comprehension and refines your application of logical rules within complex arguments. Inference: By this stage, the training wheels are off, and the student has to draw on everything they've learned so far. Their task is to mentally build a valid argument from what’s provided—or to recognize that no valid argument can be formed. What would normally be worked out slowly on paper is now done at the speed of thought. Translation: Translation helps students practice turning statements with indicator words and phrases into logical form. These indicator words, commonly found in logic books and courses, give students a sense of how to translate everyday language into formal logic. Translation breaks this process into levels, allowing students to track their progress and earn new scores as they build proficiency. Download Symbols for free and begin your journey into formal logic. Your free access includes the first level of every activity and the Modus Ponens study card, a must-have for getting started. For more advanced content and features, simply use our in-app purchases to continue building your logic skills. Start your journey of mastering the rules of inference now!

Explore Western philosophy through 104 lessons arranged into 23 courses and four year-groupings. Start with philosophical questions and ancient thinkers, then move through medieval, early modern, modern and contemporary thought. Study at your own pace. START WITH 10 FREE LESSONS The first 10 lessons are free. One optional, non-subscription in-app purchase unlocks the remaining 94. The reference and practice features below are available without that purchase. FOLLOW A STRUCTURED PATH Year 1: Foundations and ancient philosophy. Year 2: Medieval and early modern philosophy, including a course on Islamic and Jewish thinkers. Year 3: Modern philosophy, from Kant to pragmatism. Year 4: Contemporary philosophy, including language, mind, ethics, political philosophy and science. READ, QUESTION AND REVIEW - 48 philosopher profiles and an 82-term glossary. - 23 practice quizzes with 319 questions and answer explanations. - 16 thought experiments and 10 branches to explore. - Spaced review of glossary terms. - Search across lessons, courses, profiles and glossary entries. - Bookmarks, personal notes and study-progress views. - Lesson read-aloud using your device's system voice. - Home Screen widgets for a daily philosophical idea, term and thinker. STUDY INTERPRETATIONS WITH REFERENCES Dedicated source cards, daily ideas and profile passages present Liminal's original paraphrases with citations. They are interpretations for study, not verbatim translations of the cited works. READ WITHOUT A CONNECTION Lesson and reference text is bundled for offline reading, subject to the lesson unlock. Buying, restoring, checking changed purchase access and opening external links may require a connection. Narration uses the voices available on your device.