Knowing God Through Reason and Nature Alone

Natural theology is the project of establishing knowledge of God, or at least grounds for reasonably believing in God, through unaided human reason and observation of the natural world, without appeal to scripture, prophecy or any other form of special revelation, and is traditionally distinguished from revealed theology, which draws its content from a tradition's own scriptures and authoritative teaching. Classical natural theology developed several standard families of argument: cosmological arguments, reasoning from the existence of the universe to a necessary first cause; teleological or design arguments, reasoning from apparent order and purpose in nature to a designing intelligence, most famously stated in William Paley's 1802 image of a watch implying a watchmaker; and ontological arguments, reasoning from the very concept of a maximally perfect being to that being's necessary existence.

Christian, Islamic and Jewish philosophers each developed substantial natural theology traditions, drawing on Aristotelian and Neoplatonic philosophical resources shared across the three traditions, with figures including Thomas Aquinas, Ibn Sina (Avicenna) and Maimonides producing some of the most systematically developed versions of these arguments within their respective religious and philosophical contexts.