In the Righteous Mind: Why Good People Are Divided by Politics and Religion, Jonathan Haidt proposes this foundation grew from the biological behavioral immune system. This system is embedded in all animals and guides animals in what to eat and drink. It’s a subconscious, first-line defense system that protects each animal’s health by keeping the animal from eating food and drinking water that is likely to kill or sicken it. Once pathogens break the first line and enter the body, the body must spend more resources to fight off the pathogen, so there’s a biological advantage to not consuming the food. Animals that avoid smelly, rotting food and scum covered liquid are more likely to pass their genes on to the next generation so there’s an evolutionary advantage as well; animals that don’t ingest bad food are less likely to die before they procreate. The behavioral immune defense is embedded in humans as well, as evidenced by our dislike of food that we think is disgusting.
Haidt argues that the instinctive fear of strange things and people is built atop the behavioral immune system. It makes sense. Those who travel overseas know they sometimes have to be careful what they eat or drink, since their body’s immune system will be facing a somewhat different set of pathogens than what it’s used to fighting at home. The danger of getting food poisoning or contracting an illness is greater when traveling. So too is the danger visitors from other regions bring to the people in the regions they’re visiting. The European diseases unknowingly brought by colonists killed far more American Indians than bullets. The instinct to move away from someone coughing is a signal your behavioral immune system just got activated.
Our human ability for abstract thinking has enabled our behavioral immune system to respond to much more than food. The particularly interesting thing about the Sanctity-Degradation foundation is the quantity and variety of people, places, things, and symbols that can become attached to it, and the wide variety of positions different people put the same thing along the continuum from sacred/pure/good to profane/impure/bad. People often put religious symbols at one end or the other of the sanctity-degradation continuum. Since symbols have different meanings for different people, the same symbols cause each person’s behavioral immune system to react if different ways. For example, think about where a Jew and a neo-Nazi would place the Star of David and a swastika.
Symbols don’t have to have religious associations to evoke a response from the Sanctity-Degradation foundation. National flags, sports teams, political parties, gender, race, ethnic background, country of origin, sexual orientation and identification, companies and their products and services, genetically modified organisms, everything that can be considered sacred or profane, even corporate logos, can carry the strong good or bad connotations this foundation evokes.
In The Righteous Mind, Haidt uses sports as a secular way to understand the power of the Sanctity-Degradation foundation. Sports fans will cover themselves in their team’s colors, physically make the same motions, sing the same songs, and cheer and boo together. Research shows that doing actions such as these as a group, activates a part of the human brain that increases the feeling of belonging to a group and willingness to put group needs ahead of personal needs. Fans will sit on uncomfortable chairs for several hours to cheer for their team and enjoy the camaraderie of other fans. These secular activities have parallels with religion as does the passion with which some sport fans support their teams. Perhaps that is why Merriam-Webster supports the view that fan originated from fanatic which itself is Latin for temple.
Be aware that when you or someone else calls something or someone disgusting, it’s a sign this moral foundation is being triggered in you. In general, liberals and libertarians are usually not strongly influenced by the Sanctity-Degradation foundation, but whether to take in genetically modified organisms and vaccines does activate this foundation for some liberals and libertarians.