Passage Summary: An actor claims Brecht's plays fail because the characters are too confusing to understand, and you can't have a good drama if the audience doesn't care about the characters.

Conclusion: The plays written by Bertolt Brecht do not qualify as genuinely successful dramas.

Reasoning: Audiences cannot figure out the personalities of Brecht's characters, and a play cannot be a successful drama unless the audience cares about the characters.

Analysis: We are looking for a Sufficient Assumption to bridge the gap between 'not knowing a personality' and 'not caring about a character.' The argument provides a requirement for success (caring) and a fact about Brecht (no discernible personality). To guarantee the conclusion that Brecht fails, we must assume that if you can't discern a personality, you cannot care about the character. This link completes the logical chain: No Discernible Personality → No Caring → No Success.