I can totally relate to this thread.
Something happened a couple of weeks ago with my just turned three-year-old. All of the sudden she is such the critical thinker. I have no idea if it is typical for this age or not. It is hard to tell because she is so advanced verbally, has an incredible memory, and unusual interests.
I can appreciate it, but it is making my life so much harder.
Me: You need to listen to adults.
DD: Well, you need to listen to your child!
or
DD: I am not back-talking. You are just saying what I was going to say!
or
Me: If you keep back-talking me I am going to turn this car around.
DD: If you say one more word I am going to take my shoe off. (She knows this bothers me. then she did the other shoe, then the socks...)
She sounds delightful, doesn't she...
After giving her a brief and a bit biased

explanation of political parties, she came immediately to the conclusion that "Richard Nixon must have been a Republican because he was stupid enough to get impeached and resign."
She also came to the realization all on her own that "if you keep going somewhere special a lot, it won't be special anymore." My jaw dropped with that one.
She also makes up these questions for me.
DD: Which sesame street character likes to take a bath?
Me: Umm, elmo?
DD: How 'bout count, Mom? (as in c'mon, think.)
or
DD: "Let's see who can name the most Star Wars characters."
Now this is DH's thing so she is definitely explaining things to me. Once, she said, "Mom. Darth Vader's boss is a human. He is the emperor. Umm, he has a random name. Do you know it?" No, I have no idea what you are talking about.
I somewhat think her increased critical thinking and reasoning skills are a direct result of starting preschool a few weeks ago. It is the first time she has been away from me and had to really think for herself.
We also love our play based preschool.