Brains are energetically very expensive organs, and if they can’t do the important job of destinguish the words meaning, they aren’t earning their keep. Brains, in other words, are supposed to be semantic engines. What brains are made of is kazillions of molecular pieces that interact according to the strict laws of chemistry and physics, responding to shapes and forces; brains, in other words, are in fact only syntactic engines. A genuine semantic engine, responding directly to meanings, is like a perpetual motion machine—physically impossible. So how can brains accomplish their appointed task? By being syntactic engines that track or mimic the competence of the impossible semantic engine. But is this even possible? Some philosophers have argued that if the micro-causal story of how a brain works is complete (without any mysterious gaps), there is simply no room for meaning to make a difference
Philosopher Daniel Dennett's Book Intuition Pumps