Being a critical thinker means that you have the ability to judge the quality of thought, both in yourself and others. It also means that you're able to generate not just opinions but reasoned thinking.

This is much different than rationality training, which focuses on teaching people to avoid a handful of specific non-rational thought patterns that frequently occur in certain situations. But it's not about figuring out what hidden assumptions you have, learning to judge the quality of information, etc.