There is one question liberals cannot and never will answer. What moral code permits the use of government to redistribute income? Before events like the American Revolution, an individual’s place in the universe was that of serving a master of one kind or another, like a king, chief or a czar. Under that old system every person born, owed allegiance to the group he was born into and was expected to work towards the good of the group as a whole.
The question of the morality of government redistributing income has only been examined since the emergence of individual rights. Liberals or progressives if you wish are actually moving to regress back to the system that existed before individual rights became common. There are actually two moral codes. In the liberal mindset the needs of the group eclipse individual rights and every person has an obligation to contribute to the needs of the group as a whole. The difference is in how conservatives and liberals define morality.
There is certainly a perceived security in returning to the old system but it is undeniable that a huge increase in living standards has accompanied the spread of human rights.