Autant vs tant
Pourquoi boit-il autant de bière ? Is this correct? I thought autant was used in comparisons, while tant was used as an intensifier. "As much as..." vs "so much...". Does Pourquoi boit-il tant de bière? say the same thing?
The difference is thin, but it is there. "Autant" can only rightly be used when you compare two quantity together. Sure, in spoken language, people will sometimes use both "autant" and "tant", but it's not because people say it that it is right.