Three Worlds by Karl Popper

Quotes from Three Worlds, Karl Popper
The Tanner Lecture On Human Values
Delivered at The University of Michigan, April 7, 1978

“In this lecture I intend to challenge those who uphold a monist or even a dualist view of the universe; and I will propose, instead, a pluralist view. I will propose a view of the universe that recognizes at least three different but interacting sub-universes.”

If I am right that the physical world has been changed by the world 3 products of the human mind, acting through the intervention of the human mind then this means that the worlds 1, 2, and 3, can interact and, therefore, that none of them is causally closed. The thesis that the physical world is not causally closed but that it can be acted upon by world 2 and, through its intervention, by world 3, seems to be particularly hard to swallow for the materialist monist, or the physicalist.

Of course, the materialist will explain it all in terms of our brain processes; and admittedly, they do play a role in mediating the intervention of effects from world 3 through world 2 to world 1. But where the great change originated is in world 3, in our theories. These have, metaphorically speaking, a kind of life of their own, though they depend heavily on our minds and, very likely, also on our brains.”

To sum up, we arrive at the following picture of the universe.  There is the physical universe, world 1, with its most important sub-universe, that of the living organisms.  World 2, the world of conscious experience, emerges as an evolutionary product from the world of organisms.  World 3, the world of the products of the human mind, emerges as an evolutionary product from world 2.”

The feedback effect between world 3 and world 2 is of particular importance. Our minds are the creators of world 3; but world 3 in its turn not only informs our minds, but largely creates them. The very idea of a self depends on world 3 theories, especially upon a theory of time which underlies the identity of the self, the self of yesterday, of today, and of tomorrow. The learning of a language, which is a world 3 object, is itself partly a creative act and partly a feedback effect; and the full consciousness of self is anchored in our human language.”