A system is rational if it does the right thing given what it knows
Acting humanly: Turing Test
Alan Turing (1950) "Computing machinery and intelligence":
Operational test for intelligent behavior: the Imitation Game
The computer passes the test if a human interrogator, after posing some written questions, cannot tell whether the written responses come from a person or not. If the response of a computer to an unrestricted textual natural-language conversation cannot be distinguished from that of a human being then it can be said to be intelligent.
Suggested major components of AI: Natural Language Processing, Knowledge Representation, Automated Reasoning, Machine Learning
Total Turing Test: requires Computer Vision and Robotics as well