Fundamentals II
The mind-body problem
Mind-body problem: The issue of how the mind and body relate to each
other
- Elisabeth of Bohemia: Critiques how the “thinking substance” can
cause the body to produce voluntary actions
o Physical movement occurs through impulsion (the thing
moved, is ‘pushed’ by something else) and through
qualification and surface shape (the movement is
influenced by the form or figure of the surface involved)
o The immaterial soul seems incompatible with the physical
requirements of causing bodily movements
Types of -isms:
1. Monism: There is only one kind of substance
a. Materialism: Ultimately everything is material
b. Idealism: Ultimately everything is mental
2. Dualism: There are two kinds of substances
a. Substance-dualism: Mind and body are kinds of distinct
entities
Dualism: Substance-dualism
Plato believed in a soul that could reincarnate
Descartes views the body, but not the mind, as a machine
- Mind and body must therefore be different substances
- Two radically different kinds of substances: Mental and physical
o Mental substance has the property that it thinks and does
not extend in space; physical substance is extended in
space, and does not think
o He believes that the mind is inside the body (in the pineal
gland)
- This is often critiqued:
o The interaction problem (Elisabeth of Bohemia): How can a
nonmaterial entity cause physical events?
Physical causal closure says that “all physical states
have pure physical causes” (Jaegwon Kim), (Law of
Conservation of Energy)
o Pairing problem: Why is it that my mind controls my body,
rather than yours?
o Exclusion problem: If every physical event has a physical
cause, where does the mind enter?
o Brain damage problem: Why would a nonmaterial entity
react to brain damage?
o Other mystery immaterial substances turned out to be
material (phlogiston and vital force), who says this will not
happen with the immaterial mind?
,Teleportation test
- It is unclear where the soul goes when you are asleep or what
unconscious mental processes entail
- Or suppose, you were to teleport to the moon, would your mind
travel with you?
- Thinking about mind and body as separate entities seems easy
o Yet, the inability to provide a reasonable theory of mind-body
interaction has led to demise of dualism in scientific circles
Leibniz view: Monads
Monads: Not material particles, but energy-laden and soul-invested units
1. Simple monads, forming the bodies of all matter, possess
unconscious, unorganized perceptions and are driven by a tendency
to align with the universe's pre-established harmony
2. Sentient monads, found in all living organisms but absent in
inorganic matter, could feel pleasure and pain, voluntarily focus
attention, but lacked the ability to reason about their experiences
3. Rational monads, corresponding to human conscious minds,
possessed apperception—the ability to reflect on perceptions—
rooted not only in empirical evidence but also in innate truths, as
seen in the certainty of phenomena like mathematical or geometric
laws
4. The supreme monad controlled and motivated all other monads
(God of Christian religion)
Monism: Materialism
The materialist maintains that, in the end, there is only matter
- The concept of “matter” is however quite flexible (so fields, states,
processes, functions, etc. all count as “material”)
o Most important is that the mind, whatever it may be, is a part
of physical world and obeys the laws of nature
o This still leaves many possibilities for exactly what the mind is
- The problem of consciousness
o Without a spiritual mind, it’s hard to explain how and why we
have conscious mental states
Three problem areas:
Mental states (or not)
o Mental states explain behavior
Belief-desire
psychology (part of folk
psychology but also
scientific psychology)
o Theory of planned behavior
o Critique: How can a mental state
exist at all, is it just an illusion?
, Reductionism (or not)
o Explaining higher-level phenomena (e.g.,
mental states) entirely in terms of lower-
level processes (e.g., brain activity)
Subjective experience (or not)
Materialism: Eliminative Materialism
Eliminative Materialism: Denies the existence of mental states
- Mental states aren’t real and will not appear in the “ultimate
description of the universe”
o Folk psychology is just like naïve physics: with scientific
progress it will disappear
- Eliminative materialism is a bridge too far for most scientists
o Mental states appear too important for the explanation of
behavior to dismiss them
o It is also unclear what should take the place of ordinary
“belief-desire” explanations of behavior (neuroscience that
can do this, is currently science fiction)
Materialism: Reductive Materialism
Reductive Materialism: Materialism with mental states
- Denies the existence of a separate substance of the mind, but still
makes room for mental states
o (Type-type) Identity theory: Maintains that mental states
are brain states
Desire that might cause a behavior, is seen as brain
state X
For every specific type of mental state, there is
corresponding brain state that is consistent across
people and situations
One-to-one mapping of mental states to brain
states
Critique of the identity theory:
- Neural plasticity implies that the same mental functions can be
performed in different ways
- Individual differences in physical makeup suggest that brains may
be quite heterogeneous, especially at the fine-grained level of
patterns of neural connections (brain states are multiple
realizable)
o Even the same brain could encode certain thoughts or
feelings differently at different time points (identity
problem)
- Teleportation test: Suppose your mental states are your brain states
and there is a one-to-one mapping of mental states to brain states
o What about teleportation? In case you successfully reinstate
the same brain, you have thereby automatically reinstated
the same mental state
With telecopying you could say that the destruction of
your old body is murder
, Reductionism
1. Start with a scientific law in the higher order science (the science
to be reduced, e.g., psychology)
2. Establish bridge laws: one-to-one
correspondence relations between terms
in the higher order science and terms in the
lower order science (the reducing science,
e.g., neuroscience)
3. Show that the higher order law follow from
the laws of the reducing science given the
bridge laws
Materialism: Nonreductive Materialism
Nonreductive Materialism: Mental states ultimately are brain states,
but the correspondence between mental and brain states is not of the
right kind (one-to-one) to support reductionism
- Identity theory: (not type-type identity theory but) Token-token
identity
o A mental state can have different brain states depending
on the person
o We do have identity of brain states (lower level) with mental
states (higher level)
Token identity theory
The realizations can only be grouped when looking at the
higher-order collection (mental states) and not the lower
level (brain states), because the brain states are
differently realized
o This theory blocks bridge laws, because laws of psychology
cannot be reduced to the laws of biology or physics (it blocks
reduction and type-type identity)
Since mental states are multiple realizable, we
shouldn’t characterize mental states by how they are
realized in the brain
- Functionalism: Computer metaphor (Alan Turing)
o The computer metaphor extends the Turing machine into the
domain of the human mind:
Mind:body = Software:hardware
The mind is a program that “runs on” the brain
Just like the variable in a computer program, mental
states are characterized by their function, not their
realization
They also can have different realizations
Because mental states are realized differently
across people and across time, it is more helpful to
characterize them by their role in the system
than by the brain state they are realized in
o The brain is not essential
Turing test (passed): You cannot the distinguish
whether you are talking to the computer or to a human
