If you look at the welfare programs in Europe, they clearly reduce poverty (in the short-term). In the US, they haven’t worked as well, but this is unusual. I think there’s a simple reason for this: the US doesn’t spend very much money on welfare programs compared to Europe. I’m merely pointing out something that may trip you up when debating liberals.
Most arguments against welfare programs focus on morality, tearing the social fabric, the dependency cycle and the opportunity cost (more growth). I think these are very good arguments, but the debate should also focus on:
a) the long-term unsustainability of welfare programs, due to borrowing to pay for extra privileges to welfare recipients and public sector unions.
b) entitlements eliminate the possibility of open borders, which greatly improve the living standards of immigrants - and natives.