Causal Exclusion Argument

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tags: - colorclass/david marx’s theory of mind ---see also: - Principle of Causal Closure - Downward Causation - Upward Causation - Philosophy of Mind - Philosophy of Causality

The Causal Exclusion Argument is a philosophical argument that challenges the coherence of non-reductive physicalism by asserting that if physical events have sufficient physical causes, there is no room for non-physical (or higher-level) causes to exert any causal influence. This argument has significant implications for the philosophy of mind, particularly in debates about mental causation and the nature of emergent properties.

Core Components of the Argument

1. Causal Closure of the Physical: - The principle that every physical event has a sufficient physical cause. - Formally: For any physical event $P$, there exists a physical event $P^{\prime }$ such that $P^{\prime }$ is sufficient to cause $P$.

2. Non-reductive Physicalism: - The view that mental states are physical in nature but are not reducible to physical properties. Mental states have their own causal powers distinct from those of physical states.

3. Exclusion Principle: - If an event $P$ has a sufficient cause $P^{\prime }$, then no distinct event $M$ (mental event) can also be a cause of $P$ unless $M$ is identical to $P^{\prime }$.

The Argument

Kim’s Causal Exclusion Argument, as formulated by philosopher Jaegwon Kim, can be summarized in the following steps:

1. Physical Causal Closure: - Every physical event $P$ has a sufficient physical cause $P^{\prime }$.

2. Causal Sufficiency: - If a physical event $P$ has a sufficient cause $P^{\prime }$, then $P^{\prime }$ alone is enough to cause $P$.

3. Non-reductive Physicalism: - Mental events $M$ are distinct from physical events $P$ but supervene on them.

4. Causal Exclusion: - Given causal sufficiency, if $P$ is caused by $P^{\prime }$, there is no need for a distinct mental cause $M$. Any causal role played by $M$ would be redundant or excluded by the causal efficacy of $P^{\prime }$.

5. Conclusion: - Either mental events are reducible to physical events (reducing to physicalism) or they are causally impotent (epiphenomenalism).

Implications

1. Reductive Physicalism: - Supports the view that mental states are reducible to physical states, hence all causation is physical.

2. Epiphenomenalism: - Suggests that mental states are by-products of physical processes without causal efficacy, which many find counterintuitive as it implies our mental experiences have no real impact on the physical world.

3. Challenges to Non-reductive Physicalism: - Argues that non-reductive physicalism is untenable because it leads to causal overdetermination or redundancy of mental causation.

Responses to the Causal Exclusion Argument

1. Supervenience and Non-reductive Physicalism

- Supervenience: Mental properties supervene on physical properties, meaning that any change in mental properties necessitates a change in physical properties. This relationship is often seen as supportive of non-reductive physicalism, though it doesn’t fully address the exclusion problem.

- Response: Proponents argue that mental properties can still have causal efficacy by influencing the physical properties they supervene on, thus maintaining a form of downward causation.

2. Emergentism

- Strong Emergence: Argues that emergent properties have novel causal powers that are not reducible to the properties of their constituents, challenging the causal closure of the physical.

- Response: Emergentists maintain that higher-level properties can exert causal influence in ways that are not fully captured by lower-level physical causation.

3. Contextual Causation

- Contextual Emergence: Suggests that causation is context-dependent, and higher-level properties can have causal powers within specific contexts defined by the interactions of their lower-level components.

- Response: This view allows for the coexistence of physical causation and higher-level causation by emphasizing the context in which causation occurs.

4. Functionalism

- Functional Role: Mental states are defined by their functional roles in the system rather than their physical composition. They have causal efficacy by virtue of the roles they play in the functioning of the system.

- Response: Functionalism suggests that mental causation is not excluded but is understood in terms of the functional roles that mental states play in physical processes.

Philosophical Challenges and Debates

1. Multiple Realizability: - Challenge: Mental states can be realized by different physical states across different organisms, suggesting that mental causation cannot be reduced to specific physical causation. - Debate: Whether this supports non-reductive physicalism or requires a new understanding of causation.

2. Causal Overdetermination: - Challenge: The idea that an event can be caused by multiple independent sufficient causes, which seems counterintuitive and problematic. - Debate: Whether mental and physical causation leads to overdetermination or if they can be integrated coherently.

3. Epistemic vs. Ontological Emergence: - Challenge: Differentiating between properties that are emergent due to our current lack of understanding (epistemic) versus properties that are fundamentally novel (ontological). - Debate: How to classify and understand emergent properties in the context of causal exclusion.

Conclusion

The Causal Exclusion Argument presents a significant challenge to non-reductive physicalism by asserting that if physical events have sufficient physical causes, then mental events or higher-level properties cannot have independent causal efficacy. Various responses, including supervenience, emergentism, contextual causation, and functionalism, attempt to reconcile higher-level causation with the principle of causal closure. The ongoing debates highlight the complexity of understanding causation in complex systems and the nature of emergent properties.