Here's another deep philosophical dilemma. There is no way to prove whether someone else possesses consciousness or if they are merely a collection of reactions... stimulus and response. Going further, we may never know whether artificial intelligence (AI) has the ability to possess consciousness. We can verify our own thinking with René Descartes' "I think therefore I am," but when it comes to other minds it gets a bit tricky.
The Turing Test
So in order to determine if something or someone else has another mind, we may go about trying to discover if it acts like an intelligent being. In order to pass The Turing Test, a computer (or someone) must simulate a conversation that you cannot distinguish from a normal intelligent human being.
The Chinese Room
In response to the Turing Test, John Searle came up with the thought experiment called "The Chinese Room". In this case, an English speaking person is in a room. They receive letters in Chinese, read what to do on their English instructions, and then perform the correct output and deliver the Chinese letters out of the room. To somebody outside of the room, the English speaking person may pass the Turing Test of being a Chinese person if they are simulating the proper response. The English speaking person, however, has no understanding or comprehension of any Chinese language. So although something may pass a Turing Test simulating an intelligent human being, it does not necessarily mean the machine itself is thinking and understanding like one.
So what does it mean to be human? And is it possible for a machine to be sentient? The Sentient Machine by Amir Husain explores these topics in much further detail.