Are we Zombies?
The image depicts an entity that appears to be one half human and the other half has a zombielike appearance that mirrors the general shape of the human half. This alludes to the common notion that humans could, like zombies, lack a consciousness. This causes a question from the mind-body problem to arise, does consciousness exist in humans or do we consist purely of material substances. Specifically, whether humans have mental phenomena, a consciousness that impacts their physical actions or are humans fundamentally composed of physical phenomena — as is the case with zombies — and thus there is no consciousness that impacts our actions. To discuss this problem, I will analyze and evaluate some perspectives on the relationship between mental phenomena and physical phenomena regarding metaphysics and the ontology of the mind and body. Firstly, the argument of substance dualism will be discussed, which explores the plausibility of the mental being a separate existence but still impacting the actions of the physical. A common objection to substance dualism is physicalism, which will be scrutinized to provide a critical assessment of the plausibility of substance dualism and of the feasibility of existence being purely physical. Synthesising, substance dualist and physicalist views, the perspective of property dualism will be evaluated to assess the validity of there being a middle ground between mental existence and physical existence.
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The view of subject dualism was prominently defended by Rene Descartes. The argument contends that mental phenomena must exist, as denoted by Descartes’ argument of the Cogito, as the human mind thinks and that anything that thinks exists.
Furthermore, by extension of the Cogito Ergo Sum, mental phenomena are separate from the material world, and according to the claim of interactionist substance dualists, interacts causally with the physical body and thus somewhat controls its actions.
Substance dualists commonly argue this by asserting that because the mental is essentially thinking and the physical is not, then by Leibniz’s identity of indiscernibles, — which states that objects are indiscernible if they have all properties in common — mental phenomena must be ontologically separate to physical phenomena because they are discernible from each other.
This results in the conclusion that the mental, the consciousness, and the physical, the human body, are separate substances but causally affect each other.
An argument against interactionist dualism arises in the ambiguities surrounding ‘causal interaction’, a physicalist objection is how the interaction between mental and physical phenomena is plausible given that they are of different ontological categories.
If, for example, the intention to eat occurs in the mind, this intention cannot feasibly cause neurons to fire for the body to retrieve food as the mental and physical exist in different ontological planes. A reply to this problem by Arnold Geulincx and Nicolas Malebranche in occasionalism argued that mind-body interactions are a result of God’s intervention.
However, this reply is similarly logically ambiguous as it still fails to argue for ‘how’ God intervenes. The main problem is that substance dualism only logically argues that there exists a mind in humans separate from the body but the interactionist’s view of the causal effect between the mind and body is a non-logical affirmation. Physicalists provide an alternative perspective on what governs human actions; as everything is physical, human actions are determined purely by physical phenomena.
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In contrast to substance dualism, physicalism is the monist theory which argues that everything that exists, including consciousness, are composed of purely physical phenomena. Supervenience physicalism is a specific type of physicalism which argues that every phenomenon is supervened on by other physical phenomena — supervenience is the thesis that every change in some property X must entail a change in property Y.
This perspective is demonstrated by David Lewis by presenting an image of a dot-matrix; this dot-matrix is composed of dots which represent physical properties in which global properties, such as mathematics, biology, chemistry, are specific arrangements of these dots. This thought experiment illustrates that a change in global properties must necessarily entail a change in the arrangement of its dots — the physical properties. Therefore, physicalists would contend that human action, that is, a phenomenon in the physical world, must be supervened on by other physical properties.
An issue with the soundness of supervenience physicalism is the hard problem of consciousness, which challenges the fundamental premise of physicalism that everything is physical.
David Chalmers argued that physicalism fails to explain why something has consciousness because physicalism implies that by knowing every physical fact about something, we can then reductively explain the function of that thing; however, consciousness cannot be functionally analysed — analysed with respect to a specific purpose.
The reason for this, as argued by Chalmers, is the conceivability of philosophical zombies, entities functionally identical to humans but lacking human consciousness. The mere conceivability of these zombies means that one’s functional understanding of consciousness is incomplete. With a complete functional analysis of consciousness, zombies should not be conceivable as something that lacks an aspect of human function cannot logically be functionally identical to humans; it would be like supposing the notion of one metre is equal to two metres is true, which is functionally inconceivable.
Overall, though physicalism fails to explain the impact of consciousness on human actions, it argues soundly and logically that physical phenomena supervene on other physical phenomena — such as human actions. Property dualism is another argument which synthesizes dualism and physicalism, property dualists assert that human actions are supervened by both physical phenomena and mental phenomena.
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Property dualism is based on the premise established by physicalism, that physical properties supervene on other physical properties. However, the dualist aspect is that physical properties also supervene on mental properties, and vice versa. That is to say, a change in physical property X necessarily entails both a change in physical property Y and a change in mental property Z.
The key distinction between property dualism and physicalism is that physicalism contends that consciousness is a physical property while property dualism argues that consciousness is a non-physical phenomenon that is irreducible to being purely physical.
Hence, for property dualism, consciousness is a phenomenon that is non-physical by nature and supervenes on every physical change simultaneously with physical phenomena. Thomas Nagel illustrates this in a thought experiment, warmth is a physical property which necessarily entails an identical physical property of ‘mean kinetic molecular energy’, however, it also must entails a non-physical property in the consciousness of the sensation of warmth; ‘warmth’, in this cause is supervened on by both a physical property and a non-physical property. Therefore, property dualism argues that human actions can be determined by a combination of physical factors and non-physical factors — the consciousness.
However, a prominent objection to the supervening of the non-physical on the physical is the mental causation problem argued by Kim Jaegwon. Causal exclusion is the notion that every phenomenon cannot be caused by more than a singular, sufficient cause. This is combined with the physicalist’s principle of causal closure, which argues that every physical phenomenon can be sufficiently caused by physical causes. Kim therefore argues that property dualism implies, by the supervenience of both the non-physical and the physical, that every physical phenomenon possibly has two sufficient causes, the non-physical cause, and the physical cause, which contradicts causal exclusion as an effect can only be caused by a maximum of one sufficient cause.
According to the physicalists’ causal closure however, the physical phenomenon can be sufficiently caused solely by the physical cause. Therefore, as every physical phenomenon is caused sufficiently by a physical cause, the mental supervenience of property dualism is meaningless as it cannot sufficiently cause any physical phenomena — according to causal exclusion.
Therefore, mental supervenience is functionally inconsequential and epiphenomenal which means property dualism simply becomes physicalism. This would thus suggest that human actions are determined by purely physical causes, as property dualism is essentially tantamount to physicalism.
However, the logic of this conclusion commits a circular reasoning fallacy; to argue this conclusion, one must prove physicalism to verify the soundness of causal closure, proving physicalism implies that one must also logically refute all objections to physicalism — including property dualism.
Thus, a physicalist argument is used to object property dualism, but the physicalist argument is sound only when physicalism is true, however, physicalism can only be true if its objections, including property dualism, are logically refuted which results in a circular argument. Ultimately, the conclusion that property dualism presents should still be plausible after this evaluation, that both mental and physical properties supervene on human actions.
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The philosophical issue investigated throughout this essay was whether the consciousness existed and whether human actions are caused by mental phenomena or physical phenomena.
This question was investigated through the evaluation of different philosophical perspectives including substance dualism, physicalism — the negation of substance dualism, and property dualism which is the synthesis of substance dualism and physicalism.
From assessing these perspectives, substance dualism argued that a consciousness exists and is separate to physical phenomena but failed to explain the cause of interaction between the consciousness and human actions.
Physicalism argued for supervenience being the key factor that caused physical properties to interact with other physical properties but reached an illogical conclusion for the functionality of consciousness.
Property dualism combines substance dualism and physicalism to argue that the interaction between the consciousness and human actions is a manifestation of the notion that mental phenomena supervene on physical phenomena.
All things considered, substance dualism asserts the plausibility of the existence of a consciousness, physicalism argues that physical phenomena supervene on human actions and property dualism argues based on substance dualism and physicalism that consciousness exists and is a separate mental phenomenon that also supervenes on the human actions. Therefore, humans do indeed possess a consciousness and their actions are determined by both physical and mental phenomena.
