A child growing up learns to predict – that is how the child becomes capable of moving without injury and obtaining the things it needs or wants. This is the first bit of folk knowledge the child has, ‘events have causes’. Whether the child gains this knowledge by experience or is born with it (or more likely both), it becomes a foundation of our relationship with the world and our movement in it. It is a piece of folk knowledge because we all tend to believe it, we use it as a tool of thought and action, but a modern theoretical physicist would find it a difficult idea to accept without caveats. Like most of folk knowledge it is a fairly good first approximation, it will usually do, it is good enough for most occasions. Other adjectives that often replace folk are naïve, vernacular, and commonsense.

Another example is ‘things fall down’ which is pretty good for most situations; we can think differently but still find this a useful idea. ‘The sun goes around the earth’, is one bit of knowledge that we no longer accept even as a first approximation. It has become just a idiom of our language.

But as well as the folk knowledge that we use to interact with the inanimate physical world, there is also a folk knowledge that we use in social contexts. This has been called folk psychology as opposed to folk physics. Again we have a spectrum from principles that we can hardly operate without, through useful approximations, to ideas that have completely failed us. One recent picture of folk psychology as most of us experience it is the Theory of Mind. We not not actually know which parts of this theory are with us to stay, which will not be believed but still used and which will be completely rejected.

The notion of intention is probably one that is with us for good and something we cannot operate without, even probably something we are born with. Our folk ideas about emotion might turn out to be useful for a long time if a bit simplistic. On the other hand, the notion of consciousness has been drifting about for centuries, changing in nature, importance and connections to other ideas. It continues to drift. What most would think of as commonsense about consciousness has become untenable scientifically. The folk version of consciousness is likely to go the way of the geocentric universe.