“Can one change one's character? Yes, if one changes one's body.”
"Voltaire's Philosophical Dictionary"
Our emotions are physical in nature. The effects of brain damage, tumours and brain disease show us that biological factors can have deep and profound effects on our personality, memories, free will and character. Neurology and biochemistry have delved deep into the brain and discovered many of the specific parts of the brain that generate our emotions and drives. When these bits are tinkered with, severe changes to personality can be made. The way that biological change affects our personality is surely proof that consciousness and emotions are all physical, with no need for soul theory.
Modern neuroscience has proven that all mental processes start with the firing of neurones in the brain - and that this activity is itself caused by preceding firings and sensory input. In other words, modern brain scanning techniques and scientific experiments have proven that our mental life is constructed out of physical events in the brain, and nothing more.
In Neuroscience, professors Bear, Connors and Paradiso (1996)2 introduce the book with a little history of research into the brain. Several Greek scholars in the 4th century CE, 2400 years ago, believed that the brain was the center of sensation. Hippocrates, the great pagan philosopher and physician (called the 'father of medicine'), correctly taught that not only was the brain our sensing organ, but it was also the seat of our intelligence. But then, a progression of religions and cultures asserted that the heart is the source of mind - the Christian Bible is full of such references. Christians later in history were even to be found repeating Aristotle's (394-322CE) belief that the brain was merely a radiator.
Since then, biologists, neurologists, doctors and psychologists have amassed a wealth of evidence that tells us clearly and comprehensively that the physical brain is the center (and producer) of intelligence, creative thought, willpower, moral thinking and emotions. What is the point of calling our minds souls when we know that all our experiences derive from the physical actions of neurones, neurotransmitters and hormones? Not only that, but they very formation (and loss) of memory is purely physical in nature. Brain damage results in loss of memory; it must be that the soul either doesn't have any memories, or doesn't use them. Brain damage, psychoactive drugs and psychosurgery can permanently change every element of our personalities. Electrical stimulation of parts of the brain cause desire itself to arise3. All of this is only possibly if our emotions and personality are completely determined by physical, not spiritual, processes.
“We have seen that neurological and medical evidence strongly indicates that our memories, emotions, thoughts and indeed our very personalities reside in the physical particles of the brain or, more precisely, in the ways those particles interact. So this would seem to say that when our brains die, we die.
"God, the Failed Hypothesis: How Science Shows That God Does Not Exist"
Prof. Victor J. Stenger (2007)4
“Our memories and habits are bound up with the structure of the brain, in much the same way in which a river is connected with the river-bed. The water in the river is always changing, but it keeps to the same course because previous rains have worn a channel. In like manner, previous events have worn a channel in the brain, and our thoughts flow along this channel. This is the cause of memory and mental habits. But the brain, as a structure, is dissolved at death, and memory therefore may be expected to be also dissolved. There is no more reason to think otherwise than to expect a river to persist in its old course after an earthquake has raised a mountain where a valley used to be.”
Russell's watery metaphor highlights the fact that there is no apparent mechanism for a soul to influence the brain, or for the brain to influence a soul. It is as if souls do not exist, and they apparently carry out no function. If the soul copies memories that are imprinted on to the brain, then, brain damage that affects memory will also affect the soul, and it appears that brain death itself would also remove the memories of the soul. The same occurs with emotions and personality. The resolution of such philosophical problems lead to an immensely complex and improbable theory of how souls work. It is much more realistic to admit that the idea of a 'soul' makes no sense: Neurology and science has enabled us to understand the brain to such an extent that such an ethereal concept is no longer needed to explain anything. Modern brain scanning methods include a wide range of technologies, including fMRI, PET, SPECT and EEG. Using these, neuroscientists have made many exciting discoveries, including the physical basis of important thought processes. In all cases, the firing of neurones in these parts of the brains come before awareness and conscious choices are made.
“All these techniques confirm that thought processes are accompanied by localized physical activity in the brain. Let us look at just a few of the examples relevant to our discussion. Using fMRI, scientists in the United States and Brazil have discovered that the region of the brain activated when moral judgments are being made is different from the region activated for social judgments that are equally emotionally charged. [... It] is not just that physical processes in the brain take part in thinking; they seem to be responsible for the deepest thoughts that are supposed to be the province of spirit rather than matter. [...]”
"God, the Failed Hypothesis: How Science Shows That God Does Not Exist"
Prof. Victor J. Stenger (2007)6
Some people reject this type of thinking. The science is new (even if the idea of a physical basis of consciousness comes from antiquity) and it often takes a while for new discoveries to find their way into popular thinking - neophobia may play its part too. Prof. Stenger warns that "the implication that "we" are bodies and brains made of atoms and nothing more is perhaps simply too new, too disturbing, too incompatible with common preconceptions to be soon accepted into common knowledge"6, so, we, as scientists and enlightened readers, should always strife to spread the great depth of our scientific understanding of neurology and consciousness.
Below are several discussions and examples from various fields of medical science which are all only possible if emotions are physical, not spiritual, in nature.
The neurotransmitters serotonin and norepinephrine are both related to our mood, and their flow causes changes in mood. antidepressants such as tricyclics and monoamine oxidase inhibitors increase the effect of certain neurotransmitters, and thereby alter mood.7. Mood disorders are inheritable8. This means, before a person is even conscious, they are predisposed to suffer from a neurotransmitter dysfunction that causes certain moods and even some mental disorders. Free will and choice cannot overcome biology. When these symptoms become serious, depression can be lifted by the correct medication. All this shows that moods are biological in nature. If there is a soul, it is not the source of the feelings of happiness, sadness, depression, etc, and that these things can even be beyond our conscious control at all.
The frontal loves are the most recent parts of our brains and they develop last of all during gestation.
“A slight drop in blood sugar levels can also inhibit self-control, since the frontal lobes require lots of energy in order to function. [...] This research can also help explain why we get cranky when we're hungry and tired: the brain is less able to suppress the negative emotions sparked by small annoyances. A bad mood is really just a rundown prefrontal cortex.”
"The Decisive Moment: How the Brain Makes Up Its Mind" by Jonah Lehrer (2009)9
Diabetics (amongst others) who are experiencing low blood sugar undergo can undergo radical in personality. Our emotions and moods are biological, and dependent upon homeostasis: when the chemicals and neurones in our bodies and brains are askew, then so is our mind.
If things happen to our bodies that we do not choose (such as the progression of Alzheimer's disease, which causes senility and dementia)10, we are forced to change our behaviour and feelings. The cases and examples below document many occasions when disease, accidents or surgery have directly altered a person's character and personality, their life memories, their moods, and their consciousness. This is only possible if character and personality, moods and consciousness, are all biological in nature. A biology textbook concurs thusly:
“A small amount of damage [...] might even cause rather dramatic changes in your personality. Why? Because your brain is the seat of your self-awareness, the locus of your intelligence, your compassion, and your creativity. All of your mental activities - your thoughts, emotions and feelings - and all your bodily processes are affected by the functioning of your brain.”
"Understanding Human Behavior" by James V. McConnel (1986)11
As a result of encephalitis resulting from a cold virus12, Clive Wearing cannot form any long-term memories.
“Clive Wearing [...] lives in a snapshot of time, constantly believing that he has just awoken from years of unconsciousness. For example, when his wife, Deborah, enters his hospital room for the third time in a single morning, he embraces her as if they had been parted for years, saying, 'I'm conscious for the first time' and 'It's the first time I've seen anybody at all'.”
“He is so impaired that he cannot remember what happened more than 5 minutes before, with the result that he is convinced he has only just recovered consciousness. He keeps a diary and records this obsession - page upon page of records indicating the date, the time and the fact that consciousness has just been regained. When confronted with evidence ... he denies the evidence, even after many years of being in this condition [...]. Whenever his wife appears, Clive greets her with the joy appropriate to someone who has not seen a loved one for many months. She only has to leave the room for two or three minutes and return for the joy to be repeated, and always expressed in the same way.”
From 'Your Memory' by Alan Baddeley
Deborah Wearing, Clive's wife, says that "even if I just leave the room, he doesn't know if he's seen me just 10 minutes ago or 10 years ago"12. He is capable of showing all the emotions of any person, including his strong emotions for his wife, who he constantly misses. The brain damage that he suffered has caused all this, what are the implications for those that study the soul? Clive Wearing shows us that there is no 'soul' which is responsible for our emotions; or, if there is a soul, it is completely overridden by physical biochemistry. There is no part of Clive Wearing's emotions that are not affected by his brain damage. No 'soul' emerges as being responsible for those emotions. Life is purely biological and not spiritual.
In 1848, an explosion at work sent a metal pole shooting through Phineas Gage's head. He survived. The damage to his frontal lobes radically altered his personality and character. Previously he was conscientious, upright, respected. After the accident, he was suddenly abusive with profanity, irritable and had become irresponsible. Neurologists know that the front parts of the brain are associated with the tempering of impulsive behaviour, goal-setting and other areas of abstract thought.14. These ideals and aspects of personality therefore come from a biological source, not from something like a soul that is interacting with the brain.
Mary Jackson was an intelligent 19-year old student who was particularly conscientious and studious. She had a bright future as a paediatrician. But her boyfriend noticed it first, in the summer after her second year at University. She started drinking, became suddenly promiscuous, and broke up with Tom as a result. She lost all her old friends, and took crack cocaine. Nobody knew what had happened in her life. Her grades plummeted. Her adviser at University recommended a psychiatrist, but she never went. She stopped attending class. Her life fell apart. Eventually she saw a GP about an illness, where she broke down in a fit of hysterical tears, saying she had lost control of her life, and she complained that she was "unable to control her own impulses". She couldn't resist temptation. She made one reckless decision after another. She was referred to a neurologist. He found her working memory had seriously diminished, and many psychological tests just made her angry - yet she had always used to be so patient and a good student! Her internal goals and decisions were no longer moderating her behaviour.15
An MRI scan revealed a tumor in her frontal lobe, on the prefrontal cortex. She suffered from 'executive dysfunction' as the part of her brain that normally integrates emotions and rewards was becoming increasingly damaged by the tumor. As a result of this tumor, she had increasingly lost the ability to control her impulses, and her life fell apart. No-one understood why her behaviour had changed, not even her. This unfortunate case illustrates that our inner decision-making neurology is prone to biochemical and physical damage, and this can affect the very core of our agency. Mary Jackson lost her ability to control normal impulses; damage to other parts of the brain can cause massive overpowering urges.
Yet another serious case, with profound moral implications:
“There's the case of the married, middle-aged Virginia schoolteacher who suddenly started downloading child pornography and seducing young girls. His behaviour was so brazen that he was quickly arrested and convicted of child molestation; he was sent to a treatment program for pedophiles, but he was expelled from the program after propositioning several women there. Having failed rehab, he was to appear in court for sentencing, but the day before his court date, he went to the emergency room complaining of blinding headaches and a constant urge to rape his neighbour. After ordering an MRI, the doctors saw the source of the problem: he had a massive tumor lodged in his frontal cortex. After the tumor was removed, the deviant sexual urges immediately disappeared. The man was no longer a hypersexual monster. Unfortunately, this reprieve was brief; the tumor started to grow back within a year. His frontal cortex was once again incapacitated, and the urges of pedophilia returned.”
"The Decisive Moment: How the Brain Makes Up Its Mind" by Jonah Lehrer (2009)15
Psychosurgery includes medical procedures on the brain that are intended to change aspects of character. Procedures include lobotomies and leucotomies. They were used regularly from the 1930s for severely disrupted patients. Since then highly accurate and specific stereotactic tractotomies, stereotactic limbic leucotomies and the like have been developed, allowing the destruction of very small parts of the brain, normally locating particular pathways between one part and another in order to change specific aspects of behaviour and symptoms. For example, a cingulotomy is occasionally used against obsessive and compulsive patients by destroying 2-3cm of particular white matter. An amygdalotomy destroys the brain's neural connection between the amygdala and the hypothalamus and is normally used on patients who suffer from episodes of unstoppable violence and terror.16. What all this shows is that the physical structures and chemistry of the brain can control large portions of our chosen behaviours, experiences and feelings.
Henry Molaison suffered from increasingly devastating epileptic fits. He was known anonymously in medical case studies as "H.M." until his death in 200817. 55 years earlier, when he was 27, his constant fits had made his life unliveable so doctors operated on his brain, which stopped the fits. Unfortunately, a side-effect was that his memory was damaged and he lost 12 years of memories, and could not form new declarative memories. He would re-read the same magazine over and over. His motor memory was fine and he could learn new skills, although he didn't consciously know that he knew them until he was asked to try them. His knowledge of words and language was intact.14. Damage to his amygdala had damaged his ability to process emotion, and damage to his hippocampus resulted in the new-memories dysfunction. We learn from this that emotions which result from memories are completely dependent on the physical brain, as is learning. But it is emotional reactions to events around him that are of most interest here:
“He could not remember that his father had died. [...] Brenda has known him for 25 years yet she is a stranger to him each time they meet. [...] 'New events, faces, phone numbers, places, now settle in his mind for just a few seconds or minutes before they slip, like water through a sieve, and are lost from his consciousness' (Blakemore, 1988).”
There was no 'soul' that reminded Henry Molaison that his favorite Uncle had died three years ago: each time he was told, he was upset all over again. If there was a soul, why didn't it recognize Brenda and tell his body to react with happiness when he saw her? Emotions, memory, and the physical brain are all purely physical, and interconnected only by the neural pathways in the brain. It is clear from cases like this that there is no such thing as a soul.
There are many degenerative brain disorders. They gradually wear away a person's brain and mental health, and many of them alter personality and mood by interfering with the biochemistry of the brain. There are countless case studies available, documenting the onset of these diseases and the reactions of their victims. Take Alzheimer's disease, the most common form of dementia. Its incidence increases with age, affecting "about 10% of the population aged over 65, and as many as 45% over 85"19. It results in loss of function in every area of cognition, including an inevitable severe alteration of personality. Patients who have displayed a life long devotion to a religion tend to lose interest in their religion as a result of the disease20. It is eventually fatal. The main symptom is the loss of neurones and an accumulation of deposits of toxic amyloid plaques in the brain19.
Degenerative diseases have implications that extend into the realm of spirituality and religion. That these purely physical ailments can change a person's personality to a severe extent is proof that the personality itself results from physical biology, rather than from a soul or spirit. Also, the way that the accumulation of genetic errors and protein-processing mistakes can result in toxic plaques is an indication that our genetic make-up is not particularly well designed. Richard Dawkins, the foremost evolutionary biologist, points out that this is because our genes only have to get us through to the age at which we can reproduce, and support grandchildren. Beyond a certain age, there has been no evolutionary pressure for genes to keep a body functioning. This is why so many diseases are associated with old age. Some say this is all evidence for unintelligent design.
An agnosia is a type of brain damage that results in a loss of knowledge. Symptoms can be very specific. Prosopagnosia is the loss of recognition of faces. A patient can still identify faces and talk about them, but, does not recognize anyone by their face. It is caused by damage to the lower posterior temporal lobe, typically in the right hemisphere. This loss of knowledge only operates consciously; subconsciously their autonomous nervous system still reacts subtly to the presence of people they know. It is their conscious recognition itself which is damaged.21. If there was a soul integrated with the brain, and the soul contained our real selves, and had our life memories then our conscious self would still recognize people and experience relevant emotions, so damage to the brain couldn't cause these symptoms. Prosopagnosia, like many other forms of brain damage that effect consciousness, is proof that there is no soul that controls our experiences or emotional reactions.
Ann Klinestiver was a respectable high school teacher in the USA who was diagnosed with Parkinson's disease. The medication that she was on altered the dopamine system in the brain, as the dopamine neurones that control movement become damaged. The drug changed her personality and she found herself suddenly and hopelessly addicted to gambling, something which he had shunned for her whole life beforehand because she thought it was wrong.
“She started gambling as soon as the track opened, at 7 a.m., and kept playing the machines until three thirty the next morning, when the security guards kicked her out. 'Then I would go back home and gamble on the internet' [...] After a year of addictive gambling, Ann had lost more than two hundred and fifty thousand dollars. She had exhausted her retirement savings and emptied her pension fund. [...] 'I sold everything I could sell. [...] I stole quarters from my grandkids. I lost everything that mattered.''”
"The Decisive Moment: How the Brain Makes Up Its Mind" by Jonah Lehrer (2009)23
In 2006 doctors took her off of her medicine, the dopamine agonist. Her uncontrollable shaking and movement problems came back, but her gambling compulsion completely disappeared.
“Medical studies suggest that as many as 13 per cent of patients taking dopamine agonists develop severe gambling compulsions. People with no history of gambling suddenly become addicts. While most of these people obsess over slot machines, others get hooked on internet poker or blackjack. They squander everything they have.
"The Decisive Moment: How the Brain Makes Up Its Mind" by Jonah Lehrer (2009)23
The fact that such life-changing, behaviour-changing and motivation-altering effects can result from purely physical medications is proof that we are purely physical and material beings. There is no input from a "soul" into our consciousness or lives.
“A network of ring-shaped structures in the center of the brain's neocortex perched on top of the brainstem, associated with control of emotion and behavior - especially motivation, gratification, memory, and thought. [...] The limbic system's [...] neural function and connectedness of the limbic system are fundamentally similar in all mammals. [...] The most common symptoms of damage to this area of the brain include abnormalities of the emotions, including inappropriate crying or laughing, easily provoked rage, unwarranted fear, anxiety and depression, and excessive sexual interest.”
"The Brain Encyclopedia" by Carol Turkington (1996)
“If we, as Humans, had to consider one part of our brains to be the core of our personal consciousness, it would be the Limbic System and, especially, the interaction between the limbic system and the cortex.”
The Human Limbic system is the most advanced known of all animals, more complicated than even those of our closest biological relations. What separates us further from other animals, though, is the complex association-areas of the cortex and their links to the limbic system. Our 'higher functions' reside within the cortex, our emotions within the limbic system, and our 'experiences' and 'consciousness' reside in the interaction between the two.
It seems that the emotions of Love, Loss and emotion can all be invoked directly with brain chemicals, and medical cases where people have suffered brain damage, or are genetically incapable of producing or reacting to certain neurotransmitter chemicals enables us to pinpoint which emotions are caused by which neurotransmitters. As a result there is a huge catalogue of chemical treatments for various brain disorders.
Oxytocin is responsible for the loving, soothing tingly feeling we get in response to physical contact with a person whom we are attracted to physically. Dopamine is a hormone that allows oxytocin to be produced, and in a relationship Dopamine is released (through simple psychological association) by thinking about the person we love, or smelling them, or being aware that they are around. It is this association that creates the deeper-than infatuation love we associate with the person - and thus stimulates the production of the mind-chemical phenylethylamine which causes a feeling of bliss. It is phenylethylamine which makes us want to reproduce the event, such as being with that person.
People who have less oxytocin receptors, or a reduced ability to produce dopamine develop less relationships and do not become "settled down" in an relationship.
Oxytocin production can be artificially stimulated with Dopamine - causing a second-class sort of euphoria that is not associated with any particular person other than the current surroundings or situation. It is the association between person and oxytocin-euphoria that creates the deeper feeling of satisfaction which results from succeeding in obtaining what you are biologically programmed to want - human company and love. This positive-feedback system is also found in species of animals that form long term relationships.
The case of Clive Wearing shows that there is nothing extra required to cause such stimulus other than biochemistry, and because he cannot form new memories the presence of his wife will always create the happy-excitement response because he is unable to learn that she has not been away for very long. If there was a soul, surely it would not be so easily fooled! But fooled it is, and it seems that in every way, even with our most important emotions, biochemistry rules supreme.
The physiological role of the limbic system and the rise of consciousness in the processes between it and the cortex result in the emotional-experience cycle. We take into account the situation and the levels of our hormones, etc, and then conclude that we are feeling a particular emotion. Once a conclusion is reached, our limbic system assists us in reinforcing the resultant experience.
We interpret our state of physiological arousal. Each emotion does not 'have' a particular physiological state, so, our various states are interpreted rather than read24. Experimenters have taken, or manipulated, our hormone and arousal levels and found that people easily mis-interpret their causes.
We experience the most appropriate emotion depending on context and previous experience. If we are anxious we interpret this as an emotional response to our situation (even if the real reason is the drug that an experimenter has given us).
Biofeedback: Once our cortex and limbic system is primed that a particular emotion is occurring, our limbic system inhibits and excites the correct pathways in order to orientate our bodies for the correct response. If we are afraid, then we pump blood even faster. Even if the real reason our heart initially started pumping was the result of manipulation by a neurologist, if we interpret it as a fear response, our emotions and body then take on a fear response which reinforces our initial guess.
We then take in our changing surroundings, observing and thinking about what is happening, although much of this may be subconscious it still results in autonomous changes in our body's state of arousal and alertness. So, we might start to sweat in response to heat (or due to an injection of adrenaline). We then proceed round to step 1, in a continuous cycle of interpretative emotional-experience.
To illustrate this with a simple behaviour, take the study reported on by the sociologist David Myers. "Sarah is hypnotized and told to take off her shoes when a book drops on the floor. Fifteen minutes later a book drops, and Sarah quietly slips out of her loafers. "Sarah," asks the hypnotist, "why did you take off your shoes?" "Well... my feet are hot and tired," Sarah replies. "It has been a long day"25. The hypnotist knows that this is not the real reason why she acted - but - if we examine the emotional-experience cycle in the light of general behaviour, we can see that she has (1) analysed her state, and then (2) concluded subconsciously about the reasons. She doesn't know that this process goes on, and, she herself believes in her interpretation of the cause of her behaviour. We would probably find that after giving this answer, she then displays other symptoms of being tired, in accordance with cognitive dissonance theory, and thus step (4) will have her interpret other internal states as being consistent with her new feeling that she is hot and tired.
It may be surprising because it is rare to hear of it, but this theory - now backed by much evidence - has quite a long history.
“In 1884, American philosopher William James and, independently, in 1885, Danish psychologist Carl Lange, put forward related theories of emotions now commonly known as the James-Lange theory. They proposed that we experience emotion in response to physiological changes in our body. [...] Suppose you are extremely angry with someone. Imagine removing all the physiological accompaniments to the anger - your pounding heart slows, your tense muscles [...] relax, your flushed face cools. Without these 'body reactions' it is hard to imagine being as full of rage as you were. [...] The situation is obviously more complex, since individuals who have had a spine injury preventing some of these physiological reactions still feel emotion, although sometimes in dampened form.”
"Emotions and Mind" by Toates, Mackintosh and Nettle (2004)26
The qualia of our experiences are heavily based on these biochemical and cognitive processes. Our very consciousness results from biochemistry, and can be tricked by experimenters. If there is such a thing as a soul, then it seemingly has no input at all on the emotional-experience cycle, and no input on our conscious experiences. Indeed, it is as if souls do not exist. If souls do exist for some reason, they must have an experience of life so completely different from ours (not being effected by all the physical chemicals that affect our brains, emotions and consciousness), that they are more like alien observers than parts of ourselves.
Do emotions result from us having a soul, or merely from the laws of nature? Degenerative diseases of the brain that erode personality, and cases where brain damage causes sudden changes in character, are both only possible if character itself is biological. Mood disorders and mind-altering drugs indicate that the sources of feelings are biochemical. Inherited mood disorders and developmental diseases show us that personality is driven by biology. Depression, love, niceness, politeness, aggression, basic drives, abstract thinking, judgement, patience, considered behaviour, instincts, memories, language construction and comprehension, and every emotion, have turned out to have biochemical causes, not spiritual ones, and can all be radically affected by brain damage and brain surgery. If there was a soul, brain damage could not also damage our emotional feelings, but it does. Electrical stimulation of the brain causes actual desire to arise instantly. If memory, behaviour and emotions are all controlled by the physical brain, what is a soul for? It seems that there isn't anything for a soul to do - it certainly does not control behaviour or character, and, any free will it exerts is promptly overridden by biological chemistry, hence why so many diseases have an uncontrollable effect on personality. Modern science proves that the idea of souls is misguided. Everything is biological.
Skeptical Inquirer. Pro-science magazine published bimonthly by the Committee for Skeptical Inquiry, New York, USA.
"Evolution and the Unintelligent Design of Life: Inherited Traits, Genetic Dysfunction and Artificial Life" (2007). Accessed 2013 Sep 21.
Davison & Neale
Abnormal Psychology (1997). Hardback 7th edition. Published by John Wiley & Sons, Inc. Amazon link points to a newer edition than the one I've used here.
Psychology: The Science of Mind and Behaviour (1996). 3rd edition. Published by Hodder & Stoughton, London UK.
The Decisive Moment: How the Brain Makes Up Its Mind (2009). Hardback. Published by Canongate Books, Edinburgh.
McConnel, James V.
Understanding Human Behavior (1986). Hardback 5th edition. Originally published 1974. CBS College Publishing, Holt Rinehart and Winston, New York, USA.
Murphy et al.
Learning and Language (2004). A neurology textbook by Kerry Murphy, Peter Naish and Daniel Nettle. Published by the Open University, Milton Keyes, UK.
Social Psychology (1999). 6th 'international' edition. First edition 1983. Published by McGraw Hill.
Russell, Bertrand. (1872-1970)
Why I am not a Christian (1957). Quotes from Fourth Impression of 1967 edition, 1971, Unwin Books.
Stenger, Prof. Victor J.
God, the Failed Hypothesis: How Science Shows That God Does Not Exist (2007). Published by Prometheus Books. Stenger is a Nobel-prize winning physicist, and a skeptical philosopher whose research is strictly rational and evidence-based.
Toates, Mackintosh & Nettle
Emotions and Mind (2004). A neurology textbook by Frederick Toates, Bundy Mackintosh and Daniel Nettle. Published by the Open University, Milton Keynes, UK.
The Brain Encyclopedia (1996). From 1999 paperback edition published by Checkmark Books, USA.
Voltaire's Philosophical Dictionary (1764). Digital edition produced by Juliet Sutherland, Lisa Riegel and the Online Distributed Proofreading Team. Accessed via Amazon.co.uk