REVISED AND UPDATED EDITION 2024 is now available! As political polarization divides families, friends, and even countries, we tend to think we view the world from the perspective of "enlightened objectivity," and that those who disagree with us are biased, irrational, dumb, evil, or even all four. However, the Science of Epistemic Rationality-basically, the science of how we form our beliefs, and whether our beliefs are true - reveals that virtually all of us utilize multiple forms of "mis-thinking" when we form our political beliefs and when we choose which information sources to trust. We even have multiple subconscious goals that compete with and interfere with the discovery of objective truth. Highly intelligent and highly educated people do have some advantages when it comes to getting it right. However, they also have at least nine disadvantages. As explained in this book, there is a tremendous difference between intelligence and epistemic rationality. As both social media and artificial intelligence make disinformation easier and easier to spread and make people easier and easier to mislead, an understanding of how one's political beliefs are formed, and an understanding of how to form them better, have become critical! Maybe, just maybe, a better understanding of how we all form political beliefs will even help us bridge our political divide.