This has been thrown around on other threads and boards in saying that Adam Smith supported a progressive income tax but if you read it carefully he is saying that is fair to place the tax burden on the wealthy since placing in on the poor would not be just since they need all the money they earn for the basic needs of life. I think most people can agree with this but did this really advocate for a progressive income tax that is similar to what Karl Marx proposed? "A tax upon house-rents, therefore, would in general fall heaviest upon the rich" Notice he is saying that a tax on house rents and not on income would suffice for this but what most communist suggest is a kind of tax designed to turn the efforts of a person to benefit himself to benefiting the communal whole. The harder you work and more prosperous you become the more you contribute your labor to the community since its reward will be redistributed back to the community. In essence, you are working for the state-community and not for yourself which makes every person a slave.