After presenting his paper to a group of young scientists, Alan Turing is challenged by one who immediately says, "Yes, but that's not REAL thinking! Machines can't REALLY think." How might he respon

After presenting his paper to a group of young scientists, Alan Turing is challenged by one who immediately says, "Yes, but that's not REAL thinking! Machines can't REALLY think." 

How might he respond to this challenge? What is the questioner trying to argue? What does Turing's likely response tell us about the concept of "thinking?"

Do not give dictionary, wikipedia, or other online definitions. I want to see your words and ideas. Your answer must be at least 500 words in order to receive credit.