First, we, as parents, have to learn to think critically ourselves. This is no easy task because, generally, nobody taught us that, and also because one needs some level of education and/or basic understanding of how the world works in general.

Then, start asking questions: can we trust the information we receive? Is it possible we receive a biased/incomplete/wrong information? Are we being manipulated? Who would benefit from supplying us with incorrect information? correct information? How can we verify the information?

Look at the history. What can we learn from historical events? Have we been lied to in the past? How did we learn that we've been lied to? Who benefitted?