When it's pointed out that we had much higher tax rates in the past than we do now, the argument goes that those rates don't count because no one was paying those high rates to begin with because of various loopholes and deductions.
You should ask them how that's any different from right now.
IE in 1958 instead of paying
90% marginal tax rates, a clever accountant could get you down to what, 80%? Whereas today instead of paying
39.6 marginal tax rates, a clever account could get you to 35%. These people are full of shit, especially when you consider they champion the 50s and 60s as a time of FREEDOMZ while complaining Comrade Obama is taxing at record rates

Unless of course you don't pay any income taxes and thus have a 15% rate like you know, Mitt Romney.