Reason exists in the world and is perfect

Reason exists in this world and is perfect; it is reasoning that is necessarily flawed. This is for two reasons. First, the moment you try and substitute x into the real world it involves trying to partition and categorise a phenomenon in a way that can never be done. Nothing in the natural world is discrete in the mathematical sense. Second, people’s desires get confused with the reasoning – so one is never quite as rigorous as discovering a solution if it is likely to conflict with our needs and desires. And as Hume knew, reason is always the handmaiden of the passions.