In our youth most of us have biological thinking skills - our thoughts go where our hormones lead us. Obviously our genes' highest priority is to not die out so convincing us to reproduce and devote the next 20 years to childrearing dominates. So what happens when all those hormones wane. The older brain want to be the wise brain and therefore needs to figure out how to think clearly. That seems fairly straight forward but I'm collecting a set of links to show just how complex a goal that is.
The Critical Thinking Community
Stephen Downes Guide to Logical Fallacies
Wikipedia List of Cognitive Biases
Wikipedia List of Fallacies
Cognitive Bias: A Visual Study Guide