We have an innate tendency to psychological essentialism. Bruce Hood articulates this tendency well (see his book Supersense). His most vivid example is the serial-killer's shirt. If you are given a nice shirt - one that fits well and suits your style and wardrobe - and told that it once belonged to a serial killer, how will you react? Most people will avoid the shirt - even avoid touching it. Of course, the shirt contains no "serial-killer essence", but the association sparks something deep our psychology: we want to avoid objects that are associated with bad things.
This was probably hugely adaptive in our evolutionary history: if you avoid touching things that have been handled by, say, a seriously ill person, you are less likely to become infected yourself. It doesn't matter if the reason you avoid them is rooted in an accurate knowledge of the germ theory of disease or an improbable metaphysical notion of guilt-by-association - if it saves your life and is affected by your genes, it will give you a selective advantage over people without the trait, or with a weaker version of the same trait.
Essentialist psychology provides a compelling explanation for why people would believe in certain immaterial properties of matter even if the universe is completely material. Which leads some philosophical naturalists (humanists, atheists, etc) to smugly think that we've risen above the illusion: we see through the illusory sense that our instincts push us into. We aren't tricked into god-belief or imagining a life after death.
Well, it's not that easy.
I was playing with Kaia (my 2-year-old daughter), and she told me that her doll needed a nappy change*. As an expert, I was invited to conduct the procedure. I used a nose tissue to wipe the doll's bottom.
When I went to put the tissue back in my pocket (for future use), I was momentarily overcome by my inner essentialist. I had a strong sense that the tissue was unclean. All simply because of an act of imagination!
I quickly realized what was happening, and put the tissue in my pocket anyway. In fact, once I became conscious of the illusion, it quickly dissipated. Thank goodness for skepticism. I wonder if I would have recovered as quickly if I had not, a few years ago, attended a talk here in Edinburgh given by Bruce Hood.
Have you ever had a "silly essentialist" moment like this? How did you react? How did you feel once you realized what was going on?
* I feel I should point out that this wasn't one of those modern imagination-free dolls that actually produce wet nappies.