Physical causal closure is a metaphysical theory about the nature of causation in the physical realm with significant ramifications in the study of metaphysics and the mind. In a strongly stated version, physical causal closure says that "all physical states have pure physical causes" — Jaegwon Kim, or that "physical effects have only physical causes" — Agustin Vincente, p. 150.
Those who accept the theory tend, in general although not exclusively, to the physicalist view that all entities that exist are physical entities. As Karl Popper says, "The physicalist principle of closedness of the physical ... is of decisive importance and I take it as the characteristic principle of physicalism or materialism."
Physical causal closure has stronger and weaker formulations.
The stronger formulations assert that no physical event has a cause outside the physical domain — Jaegwon Kim. That is, they assert that for physical events, causes other than physical causes do not exist. (Physical events that are not causally determined may be said to have their objective chances of occurrence determined by physical causes.)
Weaker forms of the theory state that "Every physical event has a physical cause." — Barbara Montero, or that "Every physical effect (that is, caused event) has physical sufficient causes" — Agustin Vincente, (According to Vincente, a number of caveats have to be observed, among which is the postulate that "physical entities" are entities postulated by a true theory of physics, a theory of which we are ignorant today, and that such a true theory "will not include mental (or in general, dubious) concepts" (Note 5, p. 168).) or that "if we trace the causal ancestry of a physical event we need never go outside the physical domain." — Jaegwon Kim. Weaker forms of physical causal closure are synonymous with the causal completeness, the notion that "Every physical effect that has a sufficient cause has a sufficient physical cause." That is, weaker forms allow that in addition to physical causes, there may be other kinds of causes for physical events.
The notion of reductionism supplements physical causal closure with the claim that all events ultimately can be reduced to physical events. Under these circumstances, mental events are a subset of physical events and caused by them.
Physical causal closure is especially important when considering dualist theories of mind. If no physical event has a cause outside the physical realm, it would follow that non-physical mental events would be causally impotent in the physical world. However, as Kim has agreed, it seems intuitively problematic to strip mental events of their causal power. Only epiphenomenalists would agree that mental events do not have causal power, but epiphenomenalism is objectionable to many philosophers. One way of maintaining the causal powers of mental events is to assert token identity non-reductive physicalism—that mental properties supervene on neurological properties. That is, there can be no change in the mental without a corresponding change in the physical. Yet this implies that mental events can have two causes (physical and mental), a situation which apparently results in overdetermination (redundant causes), and denies the strong physical causal closure. Kim argues that if the strong physical causal closure argument is correct, the only way to maintain mental causation is to assert type identity reductive physicalism—that mental properties are neurological properties.
The validity of the physical causal closure has long been debated. In modern times, it has been pointed out that science is based on removing the subject from investigations, and by seeking objectivity. This outsider status for the observer, a third-person perspective, is said by some philosophers to have automatically severed science from the ability to examine subjective issues like consciousness and free will. A different attack upon the physical causal closure discussed by Hodgson is to claim science itself does not support the physical causal closure. Some philosophers have criticized the argument for the physical causal closure by supporting teleology and mental-to-physical causation via a soul.
There seem prima facie to be irreducible purpose-based (or teleological) explanations of some natural phenomena. For instance, the movement of a writer's fingers on the keyboard and a reader's eyes across the screen is irreducibly explained in reference to the goal of writing an intelligible sentence or of learning about the physical causal closure arguments, respectively. On the face of it, an exclusively non-teleological (descriptive) account of the neurological and biological features of hand movement and eye movement misses the point. To say, "I am moving my fingers because my brain signals are triggering muscle motion in my arms" is true, but does not exhaustively explain all the causes. In Aristotelian terms, a neurological account explains the efficient cause, while the purpose-based account explains the final cause.
The physical causal closure thesis challenges this account. It attempts to reduce all teleological final (and formal) causes to efficient causes. Goetz and Taliaferro urge that this challenge is unjustified, partly because it would imply that the real cause of arguing for the physical causal closure is neurobiological activity in the brain, not (as we know it is) the purpose-based attempt to understand the world and explain it to others.
Views of David Deutsch
Causal closure cannot be resolved if we give up at some point. For each causal explanation, new questions emerge. According to David Deutsch causal closure is impossible to be resolved in every day life (it is fallacy when it's used to assert a non-Everettian single first cause or when it's used to hide hypernymic ontological questions [like constructors] beyond specific events [like constructor results]). The correct term is "Everettian causal connectome" or "manyworlded causal connectome". Many-worlds interpretation is about alternative events, but a deeper approach on Hugh Everett's view is the many-constructors interpretation (any universe-making constructor necessarily exists; is self-caused being mathematically correct).
God is an exo-cause of the universe (not a self-cause); but still God is a self-cause of the system God—universe; thus any cosmogonic theory requires self-causation (or self-causality). God is necessarily a person; if God were a physicalist procedure then we simply distort language by merging semantics. God is a personhooded thinker, thus he requires a personhood-yielding computer (aka brain; but immaterial and not necessarily similar to ours). The idealized brain can be described topologically as a connectome with nodes (infinite brain models are possible; like a cloud of different densities and different permitted directions of informational flow). Topology doesn't have to do with specific distances (but relationships; with many of them you may get interpreted distances by observers made of the same topological stuff), but specific topological connectomes create distance-like rules (for example topology is used in the foundations of quantum mechanics; theoretically it has nothing to do with specific distances, but procedural restrictions create relative distances amongst objects created by the same rules). Thus even an idealized immaterial brain, would topologically require volume in order it doesn't merge its nodes; and thinking requires time (thinking is procedural; otherwise it would be static structure; but static structure isn't universe-like; it doesn't meet the criteria of spacetime, and it cannot be procedurally perceived if in that reality everything is static). Thus spacetime is more fundamental than brains; and God is impossible being not the utmost fundamental. God cannot resolve the causal closure by failing to being the utmost fundamental existence; thus by failing to exist (thinking requires a connectome, and God requires causal closure to be possible at the fundamental level, without Everettian alternatives).
Unprocedurality and lack of ontological definition lead to no identity, thus nonexistential nonphenomena cannot be attributed to specific entities. Without causal connectome there is no existence. Many antiphysicalists deem personhood and consciousness supernaturally self-caused and reject neuroscience (but they claim they don't reject it). Antiphysicalists (supernaturalists) don't have an analytical theory of the procedurality and immaterial ontological substance of the soul. They simplify neuroscience. They don't accept that weights of connectome activity, being pre-thoughts (biases: memories, phenotypical, hormonal, cell-component randomness [pre-consciousness before consciousness doesn't exist; not all motions inside cells are controlled perfectly]) result to thoughts. David Deutsch speaks about inexplicit thoughts (see: What is the 'Fun Criterion'? – David Deutsch – behind the scenes - YouTube). Artificial neural network small duration patterns and small duration bio-neural patterns are examples of pre-thoughts (not even inexplicit), but they make no sense as mere data activity if we don't know their particular connectome.
- Jaegwon Kim (1993). Supervenience and Mind: Selected Philosophical Essays. Cambridge University Press. p. 280. ISBN 978-0521439961.
- Vicente, A. (2006). "On the Causal Completeness of Physics" (PDF). International Studies in the Philosophy of Science. 20 (2): 149–171. doi:10.1080/02698590600814332.
- Popper and Eccles, Karl (1977). The Self and its Brain. New York: Springer. p. 51. ISBN 978-0415058988.
- Barbara Montero (2003). "Chapter 8: Varieties of causal closure". In Sven Walter; Heinz-Dieter Heckmann (eds.). Physicalism and Mental Causation: The Metaphysics of Mind and Action. Imprint Academic. p. 173. ISBN 978-0907845461.
- Sahotra Sarkar; Jessica Pfeifer (2006). "Physicalism: The causal impact argument". Physicalism. The Philosophy of Science: N-Z, Index. Taylor & Francis. p. 566. ISBN 978-0415977104.
- Max Velmans; Susan Schneider (15 April 2008). The Blackwell Companion to Consciousness. John Wiley & Sons. ISBN 978-0-470-75145-9. Retrieved 6 February 2013.
- Jaegwon Kim (1989). "The Myth of Non-Reductive Materialism". Proceedings and Addresses of the American Philosophical Association. 63 (3): 31–47. doi:10.2307/3130081. JSTOR 3130081.
- Benjamin Libet; Anthony Freeman; Keith Sutherland (2000). "Editors' introduction: The volitional brain". The Volitional Brain: Towards a Neuroscience of Free Will. Academic. pp. ix–xxii. ISBN 9780907845119.
F.T. Hong (2005). Vladimir B. Bajić; Tin Wee Tan (eds.). Information Processing and Living Systems. Imperial College Press. p. 388. ISBN 9781860946882.
The origination of free will is an illusion from the third-person perspective. However, it is a reality from the first-person perspective.
Thomas Nagel (2012). "Chapter 4: Cognition". Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature is Almost Certainly False. Oxford University Press. p. 71. ISBN 9780199919758.
[Higher-level cognitive capacities] cannot be understood through physical science alone, and ... their existence cannot be explained by a version of evolutionary theory that is physically reductive.
U Mohrhoff (2000). "The physics of interactionism". In Benjamin Libet; Anthony Freeman; Keith Sutherland (eds.). The Volitional Brain: Towards a Neuroscience of Free Will. Academic. p. 166. ISBN 9780907845119.
But the laws of physics presuppose causal closure. Hence it follows that the behaviour of matter in the presence of a causally efficacious non-material mind cannot be fully governed by those laws.
- David Hodgson (2012). "Chapter 7: Science and determinism". Rationality + Consciousness = Free Will. Oxford University Press. p. 121. ISBN 9780199845309. Hodgson relies upon the free will theorem 1 2 of scientists John Conway and Simon Kochen based upon the role of the observer in quantum mechanics, which supports the view that "belief in determinism may thus come to be seen as notably unscientific."
- Stewart Goetz; Charles Taliaferro (2008). "Strict naturalism, purposeful explanation, and freedom". Naturalism (Intervensions) (Paperback ed.). Eerdmans. p. 26. ISBN 978-0802807687.
- Falcon, Andrea. "Aristotle on Causality". Stanford Encyclopedia of Philosophy. Stanford. Retrieved 2014-03-10.