How can I evaluate something that I agree with?

Evaluation does not mean having to disprove or negate the point you have made. Some points do not have a logical opposite. However, you do not need to say whether or not the fiscal policy would increase consumption but rather answer three simple questions;

1. How long will it take to implement/come into effect?

2. How large an effect will it have?

3. Is there another policy that would be more effective?