Why YSK: A well cultivated critical thinker:
raises vital questions and problems, formulating them clearly and precisely;
gathers and assesses relevant information, using abstract ideas to interpret it effectively comes to well-reasoned conclusions and solutions, testing them against relevant criteria and standards;
thinks openmindedly within alternative systems of thought, recognizing and assessing, as need be, their assumptions, implications, and practical consequences;
and communicates effectively with others in figuring out solutions to complex problems.
There’s no easy answer for that. For me it’s people who are data-driven in their opinions, will happily explain and share that data for scrutiny, and who are generally well-regarded in their field, and therefore getting double-checked by other experts.
The nice thing about peer-reviewed science is that you don’t have to JUST vibe-check the person. All of their studies will have been reviewed by multiple scientists. It’s not a perfect system, but it’s the best we’ve come up with to date. If what they believe gets disproven by other studies, you can see how they react. Do they dig in, or do they adapt their world view?
Empathy is also important to me, so data-driven beliefs who’s execution is informed by empathy.