PHIL 255: Philosophy of Mind, Week 10

10a, Brain processes

Consciousness and brain processes: possible relations

Consciousness is independent of brain processes (spiritualist dualism).

Consciousness correlates with brain processes (naturalist dualism).

Consciousness is a set of brain processes (identity theory).

Human consciousness is a set of human brain processes (nonbiochauvinistic identity theory).

Consciousness supervenes on brain processes (functionalism).

Consciousness is caused by brain processes (epiphenomenalism).

Consciousness emerges from brain processes (emergentism).

What brain processes are relevant to understanding consciousness?

Psychology of consciousness

States of consciousness can involve: perception, emotion, attention, memory, reasoning, reflection.

States of unconscioussness: sleep, anesthesia, coma, hypnotic trance.

Anesthesia: awake state has 40 Hz frequency of neural oscillation (measured by EEG) that anesthesia stops. Many other researchers associate consciousness with the 40 Hz frequency (= 40 cycles per second).

What is a brain process?

Mechanisms are entities and activities organized such that they are productive of regular changes. (Machamer, Darden, and Craver, Philosophy of Science, 2000.)

Brain entities: neurons, neuronal parts (e.g. axons, dendrites, neurotransmitters, synapses), neuronal groups, neuronal regions.

Neuron activities: electrical signalling, neurotransmitter release, etc.

Crick and Koch on consciousness

Decomposition of the hard problem

1. Why do we experience anything at all?

2. What leads to a particular consciousness experience such as blueness?

3. Why are some aspects of human exerience impossible to convey to other people?

Explicit neuronal representation

Retinal cells (spots of light) -> neurons in primary visual cortex (lines, edges) -> neurons in higher visual cortex (moving contour) -> neurons in still higher visual cortex (shapes, e.g. faces) -> neurons in motor structures (action)

Transmission involves reencoding the information. Neurons generate meaning.

Baars on consciousness

To fully understand consciousness, we need a concept of self.

Neurologists have no trouble telling when a patient is conscious: EEG, speaking, alertness, memory, etc.

Consciousness is required for discrimination between perceptual events.

Interference in performance is explained by the limited size of the Global Workspace of consciousness.

Many aspects of consciousness are knowable, e.g. attention, perception ...

10b, More brain processes


Is consciousness an emergent property of brain mechanisms?

Criteria for emergence

(from P. Humphreys, "Emergence not Supervienience", in Philosophy of Science, 1997, supplementary volume).

1. Emergent properties are novel.

2. Emergent properties are qualitatively different from the properties from which they emerge.

3. The emergent property could not be possessed at the lower level.

4. Different laws apply to emergent features than to the features from which they emerge.

5. Emergent properties result from an interaction between their constituent properties that is essential for the emergence.

6. Emergent properties are holistic: they are properties of the entire system, not of local properties.

Examples of emergence

Life, ferromagnetism, quantum entanglements, behavior of artificial neural networks.

Emergentism is a kind of nonreductive materialism.

Application to consciousness:

1. Consciousness involves novel emergent properties - e.g. qualia.

2. These properties are qualitatively different from properties of neurons.

3. Neurons themselves are not conscious.

4. Are there laws of consciousness? Perhaps: attention.

5. Without interactions of neurons and brain regions, there would be no consciousness.

6. Consciousness is a property of the brain as a whole, not of particular neurons or brain regions.

MacLennan on consciousness

The subjective is not reducible to the objective.

Phenomena are conscious experiences (like qualia).

"Protophenomena" are atoms of consciousness.

The collective action of protophenomena produce coherent phenomena.

Protophenomena correspond one-to-one with activity sites in the brain.

Consciousness is a matter of degree.

Consciousness emerges from protophenomena, just as a picture emerges from pixels (dots).

There could be a theory of protophenomena, capturing the phenomenal aspect of consciousness.





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