I know that some policies conflict and if they are both active you enter a state of anarchy, which is bad. I want to know which ones disagree before I adopt a new policy.
Each of the conflicting policies directly states what it conflicts with, in the description of the policy tree. (Something along the lines of "You may not have both Rationalism and Piety active at the same time.") Anarchy happens when you select a new policy tree that conflicts with one of your current policy trees.
- Rationalism conflicts with Piety. You'll get anarchy if you have Piety and take Rationalism, or vice versa.
- Freedom, Autocracy, and Order mutually conflict with each other. If you have any of those three, and take a different one, you'll get anarchy.
For more details on exactly what "Anarchy" does to you, see this other question.
In basic Civ 5 and Gods and Kings:
- Rationalism and Piety conflict with each other.
- Order, Freedom and Autocracy all conflict wih each other.
Selecting a conflicting policy branch will give you 1 turn of Anarchy, and then will deactivate the first policy tree. You can switch it back on and deactivate the second policy tree, but this will also cause a turn of anarchy.
In Brave New World this does not happen.