 The second valuable contribution of recent research in this field is the development of an alternative ethical approach through the axiomatic study of the properties of indices. The main ethical axioms deal with transfers. The Pigou-Dalton principle of transfers says that inequality decreases (or social welfare increases) when an even transfer is made from a richer to a poorer individual without reversing their pairwise ranking (although this may alter their ranking relative to other individuals). Since this condition is about even transfers, it is quite weak and other axioms have been proposed in order to strengthen the priority of the worst-off. The principle of diminishing transfers (Kolm 1976) says that a Pigou-Dalton transfer has a greater impact the lower it occurs in the distribution. The principle of proportional transfers (Fleurbaey and Michel 2001) says that an inefficient transfer in which what the donor gives and what the beneficiary receives is proportional to their initial positions increases social welfare. Similar transfer axioms have been adapted to the measurement of poverty. For instance, Sen (1976) proposed the condition saying that poverty increases when an even transfer is made from someone who is below the poverty line to a richer individual (below or above the line). The other axioms with which the axiomatic analysis has been made usually have a less obvious ethical appeal, and relate to decomposability of indices, scale invariance and the like. Characterization results have been obtained, which identify classes of indices satisfying particular lists of axioms. The two ethical approaches may be combined, when one takes as an axiom the condition that the index be derived from a social welfare function with particular features.