By Agnieszka Rostalska and Rafal Urbaniak
Abstract & Introduction: Richard Swinburne (Swinburne and Shoemaker 1984; Swinburne 1986) argues that human beings currently alive have non–bodily immaterial parts called souls. In his main argument in support of this conclusion (modal argument),roughly speaking, from the assumption that it is logically possible that a human being survives the destruction of their body and a few additional premises, he infers the actual existence of souls. After a brief presentation of the argument we describe the main known objection to it, called the substitution objection(SO for short), which is raised by Alston and Smythe (1994), Zimmerman (1991)and Stump and Kretzmann (1996). We then explain Swinburne’s response to it(1996). This constitutes a background for the discussion that follows. First, we formalize Swinburne’s argument in a quantiﬁed propositional modal language so that it is logically valid and contains no tacit assumptions, clearing up some notational issues as we go. Having done that, we explain why we ﬁnd Swinburne’s response unsatisfactory. Next, we indicate that even though SO is quite compelling (albeit for a slightly diﬀerent reason than the one given previously in the literature), a weakening of one of the premises yields a valid argument for the same conclusion and yet immune to SO. Even this version of the argument, we argue, is epistemically circular.