Text: Those who claim to want a cut in the capital-gains tax rate because it will increase investment and not because it is a handout to the rich could gain a lot of credibility if they advocated reducing the rate only on future capital gains.
Entailment: If the rate on future capital gains is reduced, those who are in favor of the capital gains tax may become very credible.
Contradiction: The capital gains tax will not increase investment and is not a handout to the rich.