The Principle of Horizontal Equity : Properties and Implications

The principle of Horizontal Equity (HE), claiming that the amp;#8216;equals in all relevant senses should be treated equallyamp;#8217;, is considered as a basic principle to be followed in order to design and evaluate a redistributive policy. However, despite several indices of Horizontal Inequity (HI) having been proposed in the literature, the theoretical debate has not clarified yet amp;#8216;what is horizontal equityamp;#8217;. In this paper we aim at making clear what is the meaning of the principle of HE and its normative content. In particular we establish the true statuses of the two fundaments of the principle of HE, defining what is meant by amp;#8216;equalsamp;#8217; and then treating these amp;#8216;equalsamp;#8217; amp;#8216;equallyamp;#8217;. The former is known as the identification problem, and the latter has typically been regarded as the normative claim of horizontal equity, but perhaps surprisingly the latter may be all but empty. Our analysis brings forth a new and more appropriate definition of the principle of HE. Some implications concerning the normative meaning of an HI index and the relationship between Horizontal and Vertical Equity are derived