IT WAS COINCIDENTAL that the first hearing of the new congressional supercommittee on debt reduction took place the same day that the Census Bureau released depressing new figures about rising poverty and declining wages. Yet that accidental pairing underscores important twin truths about the panel’s work: Lawmakers should think big, reaching beyond the required mandate of $1.2 trillion to $1.5 trillion to a more ambitious debt reduction goal, preferably in the $4 trillion range.