If you know the individual is using a provoking action then yes. As an example if you can't see them you can't do anything about it.
You can't take an AoO against a creature that has total concealment from you. Losing your DEX bonus for other reasons (such as balancing on a narrow rail) wouldn't prevent you taking AoO.Thank you, a clear-cut rule is very good, now i can point to that for my players, thanks!
Just remember that when blinded, all opponents are considered to have total concealment.
Excerpt from the Glossary, emphasis mine:Blinded: The creature cannot see. It takes a –2 penalty to Armor Class, loses its Dexterity bonus to AC (if any), and takes a –4 penalty on most Strength- and Dexterity-based skill checks and on opposed Perception skill checks. All checks and activities that rely on vision (such as reading and Perception checks based on sight) automatically fail. All opponents are considered to have total concealment (50% miss chance) against the blinded character. Blind creatures must make a DC 10 Acrobatics skill check to move faster than half speed. Creatures that fail this check fall prone. Characters who remain blinded for a long time grow accustomed to these drawbacks and can overcome some of them.