The argument from desire is an argument for the existence of God. It is most known in recent times through the writings of C. S. Lewis, for whom it played pivotal role in his own conversion to theism and thence to Christianity.
As a syllogism it can be expressed as follows.
- Major premise All innate human desires have objects that exist. By "innate" we mean those desires that are universal. The desire for food, the desire for companionship, the desire to enjoy beauty are innate desires in this sense. The desires to have a grand house or a PhD are not. The premise cannot be proved but is plausible. We feel hunger; there is such a thing as eating. We feel sexual desire; there is such a thing as sex. It would be unlikely for a race of individuals to exist who reported feeling hungry yet but did not possess food, mouths nor stomachs. For every such innate desire in human experience (save one) we can identify the object.
- Minor premise There is a desire for "we know not what" whose object cannot be identified. We are never truly satisfied. For even while we satisfy our hunger, our need for companionship, love, beauty, achievement, etc. The second premise aims to articulate and appeal to the concept of "longing" as expressed by the German term Sehnsucht.
- Conclusion If the object of this desire does not exist in this world, it must exist in another.
The argument is not meant to be a proof. The conclusion may not necessarily be the only possibility satisfying the premises. Yet the argument from desire can be persuasive because the premises and conclusion can be not merely understood but "seen" in a much more direct way than similar arguments, such as the Ontological Argument. It is more directly applicable to the human experience.
The argument from desire has attracted criticisms from both religious and non-religious commentators; whilst using it as evidence for God's existence, Christian philosopher Thomas Aquinas did not consider it a valid argument for the existence of God on its own. In examining the use of the argument from desire in Aquinas's philosophy, historian Robert Pasnau criticises the argument as being "based on strong teleological assumptions few would accept today. It seems clear, contrary to his [Aquinas's] central assumption, that there are things in nature that have no point".