You can't argue with facts: a fact is something proven to be true. It's important to distinguish between fact and fiction.
When someone says, "Is that a fact?" they're asking "Is that really true?" When a detective says, "Give me the facts," he only wants information that is rock solid and confirmed. The job of science is to study things and figure out what the facts are in every field. Theories and opinions are not facts: you need to have proof for something to be a fact.