Immanuel Kant argued in the
Critique of Pure Reason that human thinking is unavoidably structured by
categories of the understanding: Kant argued that these are ideas that impose a limit to thinking. What can be known through the categories is called "things for us" and what is outside the categories is unthinkable, called "things in themselves".
John Tyndall, in the 19th century, observed that even if we were able to map the precise molecular activities in the brain, the connection between physical brain states and conscious experiences might remain intellectually impassable. This suggests that, despite advanced scientific understanding, some problems -- especially those relating to consciousness -- would evade explanation. In the early 20th century,
Friedrich Hayek argued that "the whole idea of the mind explaining itself is a logical contradiction", likening it to a generalized case of
Gödel's incompleteness theorem. Hayek was
not a naturalistic agnostic, that is, the view that science
currently cannot offer an explanation of the mind–body relationship, but in principle it could." ==Consciousness==