Based on the concept promoted by Paul Krugman – “new economy of inequality” – inequality is a process that should and can be viewed from an interdisciplinary perspective. Political life, how to regulate tax matter, the way the economy is thought offers different views on inequality. The emergence of Christian version of the Bible is also important. Moreover, the more taxes are older, much easier to accept individuals, part of them to normality. Located between two opposite-tax principles of equity and that of the non-discrimination, social tax and value the idea of citizenship is possible providence-state. While the principle of neutrality and that of non-discrimination seem to be characteristic more to a liberal state, the other principle we have mentioned - of equity, seems to correspond to a social state. If progressive taxation is rational or not, the reason are more political application, to win voters, and is considered the ultimate form of redistribution. Anyway, we accept the discrimination of a minority (from the point of view of the revenues) in order to keep the majority happy! The tax in general, but a fortiori the progressive tax, is seen as a sanction, as a sentence. Thus, the comparison between “nulla poena sine lege” corresponds to “nullum impositum sine lege”. Explained as a sign of solidarity, progressive tax bides a week economy, being borne, ultimately, for most individuals, the ancestral middle class. Today, inequality is fueled by the corruption of the political system, the provisions of tax regulation, that exemption or reduction of taxes, stand on the basis of increased inflation