Symbols Logic app for iPhone and iPad

With Symbols, learning natural deduction and the rules of inference can be done on your mobile device. Whether you are completely new to the study of logic or want a refresher on the rules of inference, our Studycards help you learn and review; and our Activities help you improve and practice your skills.

Our Studycards include: Modus Ponens, Modus Tollens, Disjunctive Syllogism, and many more.

Our Activities include:

1. Validity: Validity sneakily uses repetition to teach the student the rules of inference. Let’s face it, repetition works effectively but it can often feel like a chore. The way Validity gives you the upside of repetition while minimizing its downside is by introducing you to novel arguments that have already been “solved”. You then have to determine if the solution applied every step correctly. Repetition is at the heart of skill-building, but to minimize the feeling of “wax on and wax off” until the student is bored and frustrated, the stimulus is novel and the part that feels most like work is already laid out for you. All you have to do is determine if the steps were applied correctly.

2. Justification: Justification hides at least one part of a step from the student, forcing the user to figure out which part or parts are missing and how they fit into the larger picture of what is provided. Whereas Validity sneakily ramps up your repetition, Justification entices your creativity with what looks like a bit of a puzzle. This is intended to not only keep the student engaged, but to deepen their understanding of the rules, and more precisely, their application within an argument.

3. Inference: Inference provides a user with only a set of premises and a final conclusion. By the time the student has reached Inference, their training wheels are completely off, and everything that they learned previously must be used to either mentally construct a valid argument with what is provided or come to the conclusion that one cannot be validly drawn. What is normally completed with a paper and pencil is completed at the speed of thought.

4. Translation: Translation aids the student in translating statements with indicator words and phrases into logical statements. Indicator words and phrases are commonly used in logic books and courses to help the student get a "sense" for how to translate a statement in a human language into a statement in logic. Translation breaks them down into a set of levels and allows the user to set new scores as they reach new levels of proficiency.