The intentionality argument contends that the directedness or 'aboutness' of mental states—their capacity to be about, represent, or stand for things beyond themselves—cannot be adequately explained by purely physical processes and thus points to a non-physical dimension of reality that is best accounted for by theism. The argument's inferential structure moves from the observation that thoughts, beliefs, and desires possess intrinsic intentionality (they are inherently about objects, states of affairs, or propositions) to the claim that no purely physical state can possess this property, since physical states relate to other states only through causal connections, not semantic or representational ones. From this irreducibility of intentionality to physical properties, proponents infer that consciousness requires a non-physical explanation, with God as the ultimate source of mental phenomena and the original locus of intentionality from which finite minds derive their representational capacities.
The intentionality argument has roots in Franz Brentano's revival of the medieval scholastic notion of intentionality in Psychology from an Empirical Standpoint (1874), where he identified intentionality as the mark of the mental. Contemporary defenders include Richard Swinburne, who in The Evolution of the Soul (1986) argues that intentional states cannot be analyzed in purely physical terms, and J.P. Moreland, who in Consciousness and the Existence of God (2008) develops a detailed argument from intentionality to theism. Robert Adams in "Flavors, Colors, and God" (1987) contends that the intentional content of mental states requires grounding in a divine mind, while Angus Menuge in Agents Under Fire (2004) argues that naturalistic accounts of intentionality invariably fail to capture its essential features. Charles Taliaferro has defended versions of the argument in multiple works, including Consciousness and the Mind of God (1994).
The strongest objections come from naturalist philosophers who argue that intentionality can be naturalized through causal, functional, or teleological theories. Daniel Dennett in The Intentional Stance (1987) argues that intentionality is merely a useful interpretive strategy rather than a real property requiring explanation. Fred Dretske in Naturalizing the Mind (1995) and Ruth Millikan in Language, Thought, and Other Biological Categories (1984) propose that intentionality emerges from biological functions selected by evolution. Defenders respond that these reductive accounts either eliminate genuine intentionality or covertly presuppose it. They argue that derived intentionality (as in words or maps) always depends on original intentionality in minds, creating an infinite regress unless grounded in an unmoved source of meaning—namely, God's mind.
The intentionality argument differs from the hard problem of consciousness by focusing specifically on the representational aspect of mental states rather than phenomenal qualities. Unlike the qualia argument, which emphasizes subjective experience, this argument targets the objective directedness of thought. While the emergence problem concerns the general difficulty of consciousness arising from matter, the intentionality argument makes a more specific claim about semantic properties. Unlike mind-body dualism arguments, which focus on substance distinction, this argument specifically addresses the aboutness of mental content as evidence for theism.