Recently, in response to an article of mine, Joseph C. Schmid has argued that some traditional theistic arguments for God's unicity are problematic in that they presuppose a controversial principle and conflict with Trinitarian theology. In this article, I answer Schmid's concerns. I defend one of the original arguments while advancing new ones, and I vindicate my abductive argument for theism over naturalism.

Aquinas’ five ways are often criticized because, unless further argumentation is supplied, their conclusion is not obviously identical to the God of classical theism. Such criticism overlooks the semantic and hermeneutic functions of natural theology. By fixing the referent for the word ‘God’, the five ways allow the philosopher to provide an intelligible account of divinity. This knowledge of the cause through its effects follows the systematic structure of the triplex via (causation, negation, and eminence), a program that guides Aquinas’ account of divine attributes all the way through Summa Theologiae I qq.2-26 and Summa Contra Gentiles I. By following this rational itinerary the demonstrative power of the ways can be better assessed, looking at them not as an apologetic exercise, but as a first step in the seek for a deeper understanding of the divine source of Creation.

Enric F. Gel has recently argued that classical theism enjoys a significant advantage over Graham Oppy's naturalism. According to Gel, classical theism – unlike Oppy's naturalism – satisfactorily answers two questions: first, how many first causes are there, and second, why is it that number rather than another? In this article, I reply to Gel's argument for classical theism's advantage over Oppy's naturalism. I also draw out wider implications of my investigation for the gap problem and Christian doctrine along the way.

I argue that classical theism has a significant advantage as a theory of the First Cause over Graham Oppy's naturalistic account. This is because classical theism not only gives us a clear answer to the question of how many first causes there are but also because it explains why there is that number and not another. In comparison, Oppy's ‘initial physical state’ account seemingly leaves these questions hopelessly open, and so does his ‘metaphysical simples’ proposal for a foundational layer of reality. I end by exploring two arguments from omnipotence and perfection that could be of use also to non-classical theists.