Blacks are evolutionarily about 50,000 years behind whites. They are genetically cast for life in the jungle: low-hanging fruit and constant balmy temperatures meant they never had develop larger brains, plan for the future or strategize. Today they have IQ's that are about 15 points lower, they've got "short time horizon" thinking (i.e., they value a smaller candy bar now while whites prefer a larger candy bar later), they have higher testosterone levels and are quick-tempered and quick to violence, they have stunted moral systems (disregard for others, lying comes easily to them), higher instances of retardation, mental illness, etc.
They're basically a race of children in grown-up bodies.
Against this background, the white man's policy -- liberal, conservative, etc. -- is probably not going to make much of a difference. I'm sure that on the margins, it does. Welfare encourages tons of black births that are never cared for - except by white taxpayers. Liberalism exacerbates the problem, yes.
The problem is that conservatives imagine that if only we had a strong dose of "personal responsibility", blacks would magically turn into whites. Nope. Won't happen.