Facts about the brain
The brain is organsied into hierarchical networks.
Brain consists of about 100 billion neurons.
Each neuron can form between 5,000 & 200,000 connections with other neurons.
These interconnected systems are organised into very complex and powerful information processing networks.
Brain can be studied at several levels:
- Molecules - Synapses - Neurons - Networks - Maps - Systems - CNS
Descartes recognised that mind & brain were inextricably linked, but also believed that they were separate
He relegated the body to the status of a marvellously constructed machine
Behaviour can be researched scientifically without looking into the mental states
Learning organisms are 'black boxes' that convert inputs into outputs. Do not need to know how the 'black box' works.
Form of materialism - denys any independence of the mind
Free will is an illusion - all behaviours are determined by a combination of forces
Occams Razor = A logical principle that states that one should not make more assumptions than the minimum needed (The simplist explanation is the best)
The only thing that can exist is 'matter'
All things are composed of matter and all phenomena are the result of material interactions
'The Mind' = property of matter = the brain
Mind & Matter are fundimentally different
Science dismisses substance dualism because of the insoluble problem of the Cartesian Gap
Mind = Matter
Even if the mind comes from the brain, subjective experiences has properties that can't be reduced to brain states
'Non-reductive physicalism' - although there are low-level physical states that cause higher-level states, one can't explain higher level effects in terms of lower-level causes.
Mind states do come from brain states but cannot explain mind states in terms of brain states.
They have 'properties' that are distinct from the properties of the brain.
Subjective experience is fundamental = we know that mental states are real because we experience them.
A form of property dualism.
Developed as an answer to the mind-body problem in response to behaviourism.
Mental life can be explained in terms of higher-level functioning.
Information processing occurs at a level of abstraction that doesn't depend on the physical composition of a system.
All functional systems can be implimented in any hardware.
"The mind is the software of the brain" (Block, 1995)
"No facts about the activity of the brain could be used to confirm or refute some information-processing model of cognition" (Coltheart, 2004)
John Searle (1980)
- Cannot attribute conscious human experiences to a computer or machine.
- Computers cannot simply 'run the right program'.
- They can never have the same states as humans based solely upon functional properties.
Searle's Thought Experiment - The Chinese Room
An English speaker is lock in a room filled with boxes containing Chinese symbols (a database) and a book of instructions on how to use the symbols to make scentences (a program).
Chinese speaker posts symbols in the form of questions into the room (the input).
The English speaker uses the symbols and instructions in the room to formulate an accurate response to the questions (the output).
The program (instructions) allows the English speaker to pass the Turing Test for understanding Chinese but he does not actually understand Chinese.
Computers merely use rules to manipulate symbols, but have no understanding of the meanding or semantics.
Explain the mind in terms of observable evidence from the physical world that is obtained using scientific methods.
Complex phenomena can be explained in terms of interactions between simpler phenomena.
Explain mental phenomena in terms of the physical events that take place in the brain.
Essential for understanding the mind in terms of the brain.
Reductionist - need to understand the basic components and how they are organised to constitute a system.
Argues that Functionalist psychology is actually 'Folk' psychology.
Notions of mind based on our commonsense, everyday, subjective understanding of mental life.
Our perceptions are not always correct.
"we are decieved at every level by our introspections" (Crick, 1979).
e.g. visual illusions.
Suggests that 'folk' psychology (functionalism) will eventuall be replaced with ration, scientific, not subjective, explanations of mind in terms of neuroscience.
Behaviour and experience can only be adequately explained on the biological level.
No mental states just brain states.
Mental states posited by common-sense do not actually exist.
Argument against EM = subjective experience.
Our common sense understanding of reality (including our understanding of the 'self') is often misguided.
'Folk' psychology is based on concepts that are based on language (syntax and the semantics of 'beliefs' and 'desires').
A process that explains that relationship between two theories at different levels.
Explaining a 'high level' theory in terms of a more fundamental lower-level theory.
Neurophilosophers/Neuroscientists (but not functionalists) think that psychological phenomena can be explained in terms of neural function through the process of inter-theoretic reduction.
Example of how our introspections can be wrong
Idea of unified self
- Sperry - the divided self
- Patients with epliepsy underwent surgery to prevent eplieptic seizures spreading from one hemisphere to the other via the Corpus Callosum
- Had a Callosal Transection - Corpus Callosum severed
- Patients were relatively normal after the surgery
- Tests revealed two independent streams of consciousness - one for each hemisphere
Suggests that our subjective experience of a unified self is incorrect.
Inter-theoretic Reduction examples
1) Laws of Mendelian Inheritance reduced to Genetics
- Menel's Laws of Heredity became obsolete because they can be explained entirely by classical genetics.
- The laws don't exist separately from their mechanisms - they are explained in terms of those mechanisms.
- Shows how a higher level theory is reduced to (and eliminated by) a lower level, more fundamental theory that explains causal effects.
2) Classical Optics reduced to Quantum Optics
- Classical Optics is concerned with the geometry of light
- Classical = light behaves like a wave
- Quantum = light behaves like a particle
- Light is electromagnetic radiation - just as mental states are neural events
- Light is a wave but that wave contains particles
- Higher level theory reduced to (and eliminated by) a lower level, more fundamental theory that explains causal effects.
Inter-theoretic Reduction examples continued
3) Learning reduced to neural information processing
- Rescorla-Wagner = very clear and reliable higher level explanation of how various factors account for learning during classical conditioning.
- Marr proposed a theory on how Hebbian synapses work in the cerebellum.
- Now understand how CS, UCS, CR & UCR info is processed by synapses that learn within cerebellar neurons.
- Learning is described by Rescorla-Wagner but learning is the processing of this info in neural pathways.
- For this kind of Classical Conditioning learning theory if reduced to neural theory.
Neurons as individual units are limited to interactions with other neurons it has connections to, but the brain displays highly complex congitive processes.
Neurons act in harmony with other cells to accomplish tasks that go beyond the capability of a single individual.
The whole is greater than the sum of it's parts.
Complex behaviour emerges from the interactions of many single units following simple rules.
Reductionism & Neurophilosophy.
High level phenomena emerge from the low level domain.
The priciples of the high level phenomena are unexpected given the principles of the low level domain but can be deduced to those low level principles.
Possible to apply reductionist approaches so that the whole can be explained in terms of the parts.
Emergent consciousness could be explained using reductionist approaches.
High level phenomena emerge from low level domains but the priciples cannot be deduced to the principles of the low level domain.
The whole emerges from the sum of it's parts, it is impossible to 'reverse engineer' to explain the whole in terms of its parts
Argument against Churchlands reductionsim.