 One possible limitation of Lewis’s account is that his counterpart relation is assumed to be a qualitative similarity relation. Feldman (1971) points out that “I could have been quite unlike what I in fact am” is intuitively true, which seems to require having non-similar counterparts. Lewis responds that there are two similarity relations involved: at the relevant worlds, there is someone who is similar to me in some respect (perhaps with respect to origin), but dissimilar from me in other respects (see Lewis 1983d, 43; Lewis 1986e, 230–235). Heller (2005), Stalnaker (1986), and Fara (2009) offer further considerations against analysing counterparthood in terms of qualitative similarity.