Ms. Warren was weaselly on what her intended health reform might do to middle class taxes in the debate last night. Not good. She should find her answer and own it. Trump will say she plans to kidnap voters' children and eat them regardless of what she says, so she needs to demonstrate clarity and resolve. (And it seems mightily unlikely that any of these people would actually be able to enact their health reform ideas, however much the people desperately wish health care improvements.)
Tax policy seems super technical -- and it is. But the simple principle which should underlie it is pretty simple: government has the job of promoting the general welfare. Since that costs money, that money has to come from those who have it. Period.