@evan I'm willing to discard "machine", but for me the central question is: can we construct something that works sufficiently like the brain that it can replace humans in complex tasks?
The human brain is the most complex structure in the known universe. It is the product of 4 billion years of evolution, the last couple million of which happened in the context of groups that were hunting big game and killing one another. In a multiverse (see anthropic principle) where that process only needed to produce "us" once.
We can't even simulate a brain. To think we can construct something with similar functionality despite that requires believing most of that complexity is incidental or can be produced through some relatively simple optimization procedure. Both of which are huge leaps unjustified by any evidence. All we've managed to show is that humans have a strong tendency to anthropomorphize, which of course we already knew.