Soundness and Completeness

Universe

Here is a loose definition of soundness and completeness.

An argument is sound if everything that can be derived from it is true; no false positives.
An argument is complete if everything that is true can be derived from it; no false negatives.

Referring to Universe figure above,

• A is sound.
• B is sound and complete.
• C is complete.
• D is neither.

 B is the kind of argument, reasoning, and systems you want to be dealing with.