Popper's three worlds

Popper's three worlds is a theory developed by the British philosopher Karl Popper. It involves three interacting worlds, called world 1, world 2, and world 3. He considered these worlds real only to the extent that they allowed an epistemically relevant description of the evolution of the physical world and life.^[1]

The three worlds

The numbering of the three worlds reflects their temporal order of emergence, each realm emerging as a product of the development of previous realms. A one-word description of each realm is that World 1 is the material realm, World 2 is the mental realm, and World 3 is the cultural realm.^[1]

Popper's theory is evolutionary. Popper maintains that at the inception of the universe there was only a "World 1", a realm where everything consisted of physical states and processes. A "World 2" of mental life later emerged as a product of biological evolution. Subsequently a "World 3" of cultural objects emerged as a product of evolution of the human "World 2". Popper was a strong advocate of a theory of emergence in which each world is not predetermined by previous ones. Against this, Popper argues that we should instead see the universe as "creative" and non deterministic, and as having given rise to genuinely new levels or realms - like biological life, "World 2" and "World 3". The three worlds may be understood, in terms of this evolutionary framework, as containing three categories of entity:

World 1: the realm of states and processes as studied by the natural sciences. These include the states and processes that we seek to explain by physics and by chemistry, and also those states and processes that subsequently emerge with life and which we seek to explain by biology.

World 2: the realm of mental states and processes. These include sensations and thoughts, and include both conscious and unconscious mental states and processes. World 2 includes all animal as well as human mental experience. These mental states and processes only emerge as a product of biological activity by living organisms, and so only emerged subsequent to the emergence of living organisms within World 1. Mental states and processes are the products of evolutionary developments in the World 1 of animal brains and nervous systems, but constitute a new realm of World 2 that co-evolved by its interaction with the World 1 of brains and nervous systems.

World 3: the realm of the 'products of thought' when considered as objects in their own right. These products emerge from human "World 2" activity, but when considered as World 3 objects in their own right they have rebound effects on human World 2 thought processes. Through these rebound effects, World 3 'objects' may - via World 2-based human action on World 1 - have an indirect but powerful effect on World 1. In Popper's view, World 3 'objects' encompass a very wide range of entities, from scientific theories to works of art, from laws to institutions.^[2]

More on world 3

Popper says that his world 3 has much in common with Plato's theory of Forms or Ideas.^[3] But, world 3 is not to be conceived as a Platonic realm, because unlike the Platonic world of forms, which is non changing and exists independently of human beings, Popper's world 3 is created by human beings and is not fixed.^[4] It corresponds to the current state of our knowledge and culture.^[5]

Popper makes two key claims regarding the role of World 3 in the known universe. First, Popper argues that, despite the many continuities and correspondences between the human and animal World 2, (1) only humans consider their mental products as objects in their own right in a World 3 sense and (2) only humans have access to World 3 objects. Second, World 3 has no direct effect on World 1 but only affects World 1 as mediated by the human World 2. For example, a theory of nuclear reactions will never of itself cause a nuclear reactor to be built, yet the existence of a nuclear reactor is not the result of a purely World 1 process but is the eventual product of complex interactions between particular World 3 theories and human World 2 mental activity, and also particular World 2 and World 1 mind-brain-body interactions, leading to particular World 1 human actions (to construct a nuclear reactor) only made feasible by this complex set of interactions.

The interaction of world 1 and world 2

The theory of interaction between world 1 and world 2 is an alternative theory to Cartesian dualism, which is based on the theory that the universe is composed of two essential substances: res cogitans and res extensa. Popperian cosmology rejects this essentialism, but maintains the common sense view that physical and mental states exist, and they interact.

The interaction of world 2 and world 3

The interaction of world 2 and world 3 is based on the theory that world 3 is partially autonomous. For example, the development of scientific theories in world 3 leads to unintended consequences, in that problems and contradictions are discovered by world 2. Another example is that the process of learning causes world 3 to change world 2.

The interaction of world 3 and world 1

The world 3 objects are embodied in world 1. For example, the intrinsic value of Hamlet as a world 3 object is embodied many times in world 1. But, this representation of an object of world 3 in world 1^[6] is not considered an interaction in Popper's view. Instead, for Popper, because world 3 is a world of abstractions, it can only interact with world 1 through world 2.^[7]^[8]

References

^ ^a ^b Eccles 1970, p. 163–169.
^ Heller 2011, p. 118–120.
^ Popper 1972, Chap. 3.
^ Niiniluoto 2006, p. 61: "The most important difference between Platonism and Popper is the fact that world 3 is created by human beings."
^ Eccles 1970, p. 165: "Most important components of world 3 are the theoretical systems comprising scientific problems and the critical arguments generated by discussions of these problems."
^ Popper 1994, Chap. 1.
^ Eccles 1970, p. 165: "Popper specifies for these three worlds, namely that there is reciprocal transmission between 1 and 2 and between 2 and 3, but that 1 and 3 can interact only by mediation of World 2."
^ Popper 1972, p. 155: "The first world and the third world cannot interact, save through the intervention of the second world, the world of subjective or personal experiences."

Works cited

Eccles, J. C. (1970). Facing Reality: Philosophical Adventures by a Brain Scientist. Springer Science & Business Media. ISBN 978-1-4757-3997-8.
Heller, Michael (2011). Philosophy in Science: An Historical Introduction. Springer.
Niiniluoto, Ilkka (2006). "World 3: A Critical Defence". In Jarvie, Ian; Milford, Karl; Miller, David (eds.). Karl Popper: Metaphysics and epistemology. Ashgate.
Popper, Karl (1968) [reprinted in Popper 1972, chap. 3.]. Epistemology Without a Knowing Subject. Third International Congress for Logic, Methodology and Philosophy of Science, 25 August 1967. Amsterdam.
Popper, Karl (1972). Objective Knowledge: An Evolutionary Approach.
Popper, Karl R. (1994) [Based on his Emory University lectures 1969]. Knowledge and the body-mind problem : in defence of interaction. Mark Amadeus Notturno. London: Routledge. ISBN 0-415-11504-3. OCLC 30318882.