Kurzweil had a nice end-run around this problem. It doesn't matter whether the machine is sentient/intelligent/understands/etc. It matters whether the machine can convince humans that it is doing these things. There is of course still room for skepticism, as a researcher could uncover new, testable ways in which the machine isn't actually living up to our definition of any of these concepts. But if all that is left to decide the question is the way in which the thing doing the convincing happens to be implemented, then you're in the land of xenophobia to claim that as a determining factor.

AFAICT this is one step further than the Turing test which is blind (or perhaps double blind). In this test the human starts interacting with something that is clearly a machine, then comes away convinced that the machine possesses non-machine qualities like sentience, a soul, etc. I don't remember Kurzweil addressing whether the machine itself would argue this on its own behalf, but that seems likely.

Edit: clarification