In his acclaimed 2003 book, Darwin’s Cathedral: Evolution, Religion, and the Nature of Society, David Sloan Wilson, Distinguished Professor of Biology and Anthropology at Binghamton University, draws an important distinction between “practical truth” and “factual truth.” Practical truth is that which reliably produces personal wholeness and social coherence by motivating people to behave in ways that serve the wellbeing of the group. Factual truth is that which is measurably, scientifically real. Wilson’s perspective is framed within a larger theoretical discussion of group selection and multi-level selection:

What do I mean by factual and practical realism? A belief is factually realistic when it accurately describes what’s really out there (e.g., there are no people up there sitting on clouds). A belief is practically realistic when it causes the believer to behave adaptively in the real world.

Here’s an example of why practical realism has historically trumped factual realism…

In group to group conflicts, any culture that offers the promise of an afterlife to those who heroically martyr themselves will likely triumph over an army of atheists who have the rational belief that death marks the absolute end of individual existence. Over the eons of human evolution, such selective processes would tend to favour the maintenance of beliefs in that which was known experientially to be practically real, whether or not those beliefs had any basis in measurable, factual reality.

Elsewhere, David Sloan Wilson writes:

If there is a trade-off between the two forms of realism, such that our beliefs can become more adaptive only by becoming factually less true, then factual realism will be the loser every time. … Factual realists detached from practical reality were not among our ancestors. It is the person who elevates factual truth above practical truth who must be accused of mental weakness from an evolutionary perspective.