In "Female Orations" ...

Why does the second speaker think that women's efforts to improve their lot will be fruitless?

The answer is that "women shouldn't unite because men won't listen to what they are saying".

Explanation:

This obviously is the opinion of the second speaker.

Speaker one said that "women should unite to free themselves from the control of men"

Speaker three also gave his own opinion as: " women should blame and hate Nature for the inequalities

women need men to live because men provide everything for women".

The second speaker negates the opinion of other speakers by saying that "women shouldn't unite because men won't listen to what they are saying".