Barry Beyerstein lists five main types of empirical evidence which support the dependence of consciousness on the brain.His is work is often cited by Atheist bloggers as irrefutable evidence against the existence of a non-physical consciousness.
Empirical evidence is that data which has been acquired via observation,experimentation,replication and published in peer reviewed journals (hopefully not behind any paywalls).With that in mind,let's flesh out the empirical evidence from the conjecture;
1."First, phylogenetic evidence refers to the evolutionary relationship between the complexity of the brain and a species' cognitive traits (Beyerstein 45). Corliss Lamont sums up this evidence: "We find that the greater the size of the brain and its cerebral cortex in relation to the animal body and the greater their complexity, the higher and more versatile the form of life" (Lamont 63)."
The brain-to-body-mass-ratio myth has been around since the days of Aristotle.Fortunately,contemporary neuroscience has adequately refuted this myth in this article .Humans and mice for example have similar brain/body size ratio.According to Beyerstein and company,mice should be either on par with human intelligence or second smartest creatures on this planet.To make matters even worse,small birds have relatively larger brains than humans according to their E/S (brain/body weight) ratio.This would mean birds are the most intelligent creatures on the planet,and the term "bird brain" takes on a whole new meaning.Bird brain = Einstein.
2 Second, the developmental evidence for mind-brain dependence is that mental abilities emerge with the development of the brain; failure in brain development prevents mental development (Beyerstein 45)
Dualists admit that the brain can influence the mind and vice versa.However,the Materialist begs the question when he assumes that functional dependence equals existential dependence.For example:I depend on my computer for certain tasks,entertainment,communication,etc. Should my computer be destroyed,it does not mean I am destroyed too in the process.My survival is existentially independent from my computer but I depend on it to function for certain activities.
This is what is meant by the mind being functionally dependent on the brain but existentially independent from the brain.
3.Third, clinical evidence consists of cases of brain damage that result from accidents, toxins, diseases, and malnutrition that often result in irreversible losses of mental functioning (45).If the mind could exist independently of the brain, why couldn't the mind compensate for lost faculties when brain cells die after brain damage? (46)"
Dualist philosopher,William James, developed his transmission theory of consciousness,which posits that the mind-body relationship is bi-directional,ie. the effects run both ways.Mind can influence body - and body can influence mind.James delivered his Ingersoll Lecture in 1898 which formulates the actual position adopted by contemporary dualist philosophers and not the caricature invented by Beyerstein et al,which forces dualists to defend a straw man.
As has said William James:"Every one knows that arrests of brain development occasion imbecility, that blows on the head abolish memory or consciousness, and that brain-stimulants and poisons change the quality of our ideas.’ He then makes the point that modern physiologists ‘have only shown this generally admitted fact of a dependence to be detailed and minute’ in that ‘the various special forms of thinking are functions of special portions of the brain."
Thus the clinical evidence showing disease,toxins and accidents influencing mental states are consistent with the transmission theory of dualism,and does not in the least undermine it.As for the argument that mind must compensate for lost faculties is a non sequitir that conflates the types of dependence I mentioned above (in no.2).The mind is functionally dependent on the body to operate in the material plane.Therefore any damage to the brain will cause a distortion in consciousness but the mind does not depend on the body for survival,just as I don't depend on my cell phone for my existence even if my phone no longer functions.
Note: This mind-body issue regarding its ontology and functionality is an extremely difficult concept to follow for any Materialist.They cannot allow themselves to understand it and require repeated explanations.
4.Fourth, the strongest empirical evidence for mind-brain dependence is derived from experiments in neuroscience. Mental states are correlated with brain states; electrical or chemical stimulation of the human brain invokes perceptions, memories, desires, and other mental states (45).False.The evidence of neuroscience remains neutral concerning the mind-brain ontological issues.The Materialist assumes neuroscience supports metaphysical naturalism because they interpret the data in such a way to support their a priori beliefs.For example,when the Materialist concludes that brain causes consciousness/mind because certain mental states are correlated with certain brain states,he is committing a logical fallacy called Cum hoc ergo propter hoc.If X and Y occured simultaneously then X caused Y.This type of reasoning fails to account for other possible explanations,and that possibly the direction of causation could be the reverse.
5.Finally, the experiential evidence for mind-brain dependence consists of the effects of several different types of drugs which predictably affect mental states (45).
This argument is a variant of numbers 2-4 which I've already dealt with.The unstated assumption is that drugs (a physical/chemical substance) must not affect the mind if dualism is true.But dualism makes no such claims and happily concedes that chemicals alter consciousness.Dualism postulates a bidirectional influence regarding the mental and physical relationship.See William James quote in no.3