Students, like most others, eventually get into a pattern of thinking. This occurs when the information is presented to them and they take the fastest most obvious answer. The problem is that there is no such thing as the "obvious" answer in science. There is always more depth to the problem, usually multiple solutions, and the potential for different conclusions. Choosing the conclusion that makes the most logical sense leads to a more critical thinker. To think beyond the audience means to think for oneself.
Once students begin the process of thinking for themselves they open a world of new understanding by questioning common mob wisdom. They are not confrontational thinkers that always think in polar opposites but they are able to see the differences in group think and the potential for better understanding.
How does one get to think for oneself?
They must learn to question their world in a way that leads them to their own conclusions. While it is highly unlikely you can transform a person's thinking through higher education alone without their innate ability to develop you can sow the seeds to critical thinking.
Professors can do this through encourage students to think through alternatives. If they start with a belief then it is helpful to push them to understand where that belief comes from and how they may challenge their assumptions by always looking deeper and at others perspective. Typically this is done through asking thoughtful questions and challenging holes in their logic. This may not always work as students must be open to the possibility that they are "wrong"; as defined by further depth. Something most of our egos can't handle.