The expression, a critical thinker could fit. It is an invaluable academic skill which once learned is never forgotten.
It means not taking what you hear or read at face value, but using
your critical faculties to weigh up the evidence, and considering the
implications and conclusions of what the writer is saying.
On Critical thinking.org there is a cool wheel which lists the characteristics of critical thinking.
and finally on Wikipedia we have this (emphasis mine):
Critical thinking is a way of deciding whether a claim is always true,
sometimes true, partly true, or false. It can be traced in the West to
ancient Greece with its Socratic method and in the East to ancient
India with the Buddhist kalama sutta and abhidharma literature.
Critical thinking is an important component of most professions [...]
Critical thinking employs not only logic but broad intellectual criteria such as clarity, credibility, accuracy, precision, relevance, depth, breadth, significance, and fairness.