Substance Dualism and Critiques
The Interaction Problem and the Critique of Substance Dualism
Transition from Descartes' Arguments: While previous discussions focused on Descartes' arguments favoring substance dualism, most current philosophers of mind reject the theory. Substance dualism is not inherently a superstitious or "ghost story" belief; it is simply the ontological claim that the mental and physical are distinct, independent substances.
Princess Elizabeth of Bohemia's Critique: Princess Elizabeth, a contemporary of Descartes, engaged in a long correspondence with him and formulated a fundamental objection based on the nature of substances.
Defining Substance: By definition, a substance is a fundamental kind of thing that depends on nothing else for its existence (or at least nothing else finite).
Causal Independence: Discrete substances cannot be dependent on one another.
Example of Hands and Computers: A computer and the hands used to type on it are agreed to be the same physical substance. Therefore, they can depend on or interact with each other without contradiction.
The Problem of Difference: If the mind and body are truly distinct substances, they should not be able to causally influence one another, as that would suggest a dependency that contradicts their status as independent substances.
The Difficulty of Mind-Body Interaction
Causal Influence in Everyday Life: There is overwhelming experiential evidence that the mind and body interact, yet substance dualism struggles to explain how.
Mental to Physical: Deciding to raise a hand results in the physical action of the hand rising. Volitions like wanting to drink a Coke or walk out of a room lead to physical movements. This suggests that mentality causes physicality to act.
Physical to Mental: A mosquito bite (a physical event) results in an itch (a mental event/sensation). External stimuli like light waves from a computer screen cause events in the mind.
The Charge of Telekinesis: Without a physical mechanism, the claim that an immaterial mind moves a material body sounds like telekinesis—the supposed ability to move objects with the mind alone (e.g., staring at a spoon to make it bend). While Descartes would not use this term, the logic of his system implies that mind simply "makes matter do stuff" without physical contact.
Descartes' Attempted Solution: Descartes argued that the soul is joined to the body at a specific "seat of the soul," identifying it potentially as a particular gland in the brain (the pineal gland). Here, he suggested the soul and body intermingle and exchange messages.
Elizabeth's Rejection of the "Gland" Solution: Elizabeth pointed out that physical things move via pushing, pulling, and specific laws (e.g., gravity, electromagnetism).
If the mental realm operates through willing and deciding rather than these physical laws, a physical gland cannot bridge the gap.
Moving a body requires extension or physical force, which an immaterial thing lacks.
The "Primitive Notion" Defense: Descartes eventually responded by claiming that the mind-body union is a "primitive notion." He argued that this union is intelligible only in its own right and cannot be explained further because it is so basic to existence. In this view, the union is a fundamental mystery.
Elizabeth’s Lean Toward Materialism: Elizabeth famously noted (p. 49) that she would find it easier to concede that the mind is matter/extended than to believe an immaterial thing could move a body. She would rather accept materialism—despite its own conceptual difficulties—than accept that mental forces interfere with the laws of physics.
Leibniz and the Parallelism Alternative
Gottfried Wilhelm Leibniz's Dualism: Leibniz shared Descartes' dualist convictions but recognized the strength of Elizabeth's causal argument. To solve it, he proposed a radical theory that denied interaction entirely.
The Two Clocks Analogy: Leibniz suggested that the mind and body are like two clocks wound up by God to run in perfect synchronicity. They appear to interact (e.g., a mosquito bite seemingly causing an itch), but they are actually just following pre-established paths that coincide perfectly.
The "Bullet Biting" View: A "bullet biting" view is one where a thinker accepts a highly counterintuitive or implausible conclusion to maintain a specific theory. Leibniz had to accept that we are in "massive error" about our common-sense experience of mental causation to keep substance dualism intact. He eventually argued that nothing in the universe truly interacts causally.
Jaegwon Kim and the Pairing Problem
The pairing problem is a modern development of the causal argument against dualism. It asks how we can pair a specific cause with a specific effect when dealing with immaterial entities.
Causal Pairing in Physical Space: Consider two guns, gun and gun . If gun is fired and person is hit, while gun is fired and person is hit, we explain this pairing through spatial relationships (e.g., gun was aimed at ; gun was aimed at ). Spatial location individuates physical causes.
The Problem for Souls: Kim posits a scenario (p. 52): suppose there are two souls, and , with the same intrinsic properties. Both act at the same time to cause a change in material object .
How do we determine that soul caused the change in rather than soul ?
If we say soul is "in" or "attached to" body , we are using spatial language.
Non-Spatiality of the Mind: Descartes’ Argument 4 (p. 38) states that the mind's essential nature is to be non-extended and have no location in space. If a dualist admits souls have spatial locations to solve the pairing problem, they sacrifice a core argument for dualism and move away from Descartes’ original theory.
The Exclusion Principle: Physical objects exclude each other from spatial regions; two objects cannot occupy the same point in space and time. If minds are in space, it remains unclear how an immaterial mind can coexist in the same space as a brain, or how many minds could occupy one body.
Introduction to Property Dualism
Beyond Substance Dualism: Because substance dualism leads to complicated puzzles regarding causation and spatiality, many contemporary philosophers look toward Property Dualism.
Definition: Property dualism holds that there is only one substance in the world (physical substance), but this substance possesses two distinct types of properties: physical properties and non-physical (mental) properties.
Relationship to Physicalism: Property dualism is often seen as consistent with non-reductive physicalism and emergentist dualism.
Core Concept: One can affirm that the mind is not identical to the body and has a distinct essence (the conclusion of Descartes' arguments) without claiming the mind is a separate "soul" substance. Thinking is viewed as a non-physical property of a physical substance, a property that physics does not explore. This provides a "weaker" but more manageable form of dualism that avoids the "intermingling" problems of Cartesian souls.