A lot of disagreements between people are due to honest emphasis on mutually exclusive propositions, both of which have clear value. Examples include social responsibility versus personal liberty, or freedom of speech versus the protection of minorities. In other cases, one party to a debate is just plain wrong, misinformed, or invested in error for extraneous and/or personal reasons. This includes the “divine right of kings” and “separate but equal” racial segregation. Society makes its way along the centuries by recognizing, and dispensing with, the erroneous (e.g., divine right) while building up institutions that can justly scrutinize the real debates, hopefully reaching the right decision more often than not.

The current debate between science and religion, in particular discussions of evolution and public education in the United States, is mostly a phenomenon of the erroneous sort. Some opinions of the partisans, while zealous in their delivery, are just plain wrong. However, making things more complicated is the fact that the “plain wrong” errors are committed by more than one party. On the one hand, the idea that the natural world around us does not teem with evidence in support of Darwin’s theory of evolution, that humanity does not share common ancestry with other forms of life on Earth via the mechanism of descent with modification, is profoundly mistaken. You, I, and the rest of humanity are so part of the Tree of Life, this book is to help you count the ways. Equally wrong is the notion that acceptance of this evidence of biological evolution spells doom to a religious worldview (it doesn’t), or that Darwin told us anything definitive about the origin of life or how we could be good atheists (he didn’t).