Analyze Categorical Syllogisms
Build logical arguments from premises, visualize validity with animated Venn diagrams, and learn the rules of formal logic through hands-on exploration.
Build logical arguments from premises, visualize validity with animated Venn diagrams, and learn the rules of formal logic through hands-on exploration.
Categorical syllogisms — the cornerstone of formal logic since Aristotle — are typically taught through dry textbook exercises. Most online tools are simple multiple-choice quizzes. There's a gap for an interactive tool that lets you build syllogisms piece by piece, see the Venn diagram update in real time, and understand why an argument is valid or invalid.
Logic Lens is a categorical syllogism analyzer. You choose three terms (major, middle, minor), select the proposition type for each premise and the conclusion (A/E/I/O), pick the figure, and the tool checks whether your syllogism is logically valid — showing animated Venn diagrams, the mood-and-figure classification, traditional names (Barbara, Celarent, etc.), and any fallacies committed.
Under the hood, Logic Lens implements the full validity checker for all 256 possible mood-and-figure combinations. It applies the five classical rules of syllogistic validity: (1) the middle term must be distributed at least once, (2) any term distributed in the conclusion must be distributed in its premise, (3) no two negative premises, (4) a negative premise requires a negative conclusion, and (5) two universal premises cannot yield a particular conclusion. The Venn diagram renders three overlapping circles with animated shading for exclusions and marks for inclusions.