If you haven’t already, you can read my correlation does not imply causation, uh, rant here. The general idea is that, just because you see that events A and B go together, you cannot conclude that event A causes event B. You can only conclude this if you rule out two other possibilities, namely that event B causes event A or that an outside event C causes both events A and B. Otherwise you can run into such absurd logic as the following:
Technically, I suppose I can’t rule out the notion that the logic is correct- maybe there is something about the political process in Illinois that turns people on to criminal behavior. Nonetheless, I can’t conclude that that is what is going on unless I can rule out the possibility that either people become politicians because they exhibit criminal behavior (and need to figure out how to cover it up?) or that some biological or environmental trait leads people to being both politicians and criminals.
If this really is more concentrated in Illinois than elsewhere (I was born in the land of Jim Traficant, so I am not a good judge of this), then perhaps it’s something in the water or the deep dish pizzas or something.