A nice synopsis from Independent via Early-Retirement.org:
It seems to me that the same pros and cons show up every time someone says “progressive taxes”. Here’s my list of “pros”, with numbers for easy reference.
Note that the items are not necessarily independent or consistent, and the list probably isn't complete – these are just arguments that I’ve heard that seem plausible.
I’ll let someone else take the “cons”.
1) Can’t get blood from a turnip
2) Got to go where the money is
3) Some gov’t spending explicitly supports the poor. It’s silly to tax the poor or lower middle for this spending
4) High earners make more per hour, consequently higher tax rates on them leave more level incentive to work
5) It’s better to tax dumb luck than hard work (this may be identical to (4), or may be a “fairness” argument)
6) High income/high wealth have more to protect, hence should/would pay more for protective services
7) Same as (6), but expanded to entire social structure
8.) Low income get more utility from marginal income, hence we increase total utility by shifting taxes to higher income
Social structure arguments
9 ) Prefer more uniform distribution of income/wealth – don’t like societies with extremes of rich and poor
10) Concentration of wealth gives excessive power to a few (this also supports wealth taxes)
11) Our system generates large (unfair) differences in opportunity, progressive taxes somewhat offset this