Ask an AI data tool “Why did revenue fall in March?” and it gives you one plausible story. But plausible isn’t the same as correct.

Argue With My Data treats that question as an investigation. Upload a CSV or Excel file and ask your question. The app calculates the real change in code, then Gemma 4 proposes competing explanations: a lost customer, a product mix shift, a regional decline, a data-quality problem or seasonality. Each explanation gets a pass/fail threshold fixed before it’s tested. Deterministic pandas and DuckDB tools test every explanation, every result is recomputed and verified, and each one is labelled SUPPORTED, WEAKENED, REJECTED or UNTESTABLE, with an evidence trace.

Gemma also acts as an adversarial critic, but it never does the maths and can’t change a verdict. The app shows, step by step, whether Gemma actually answered.