Materialism believes that everything is a material object. There're no minds, souls or spirits that are non-material. Everything is physical only. Materialists argue their claim with the brain chemistry argument. According to brain chemistry, those functions that are considered to be working with mentality, such as thinking, memory, emotion or pain, are results of chemical processes in brain. Everything is the outcome of psychological condition by means of drugs and other physical therapies. For example, when we love someone, it's not that our soul is existing and causing love, but it's hormone which is causing brain to love someone or something. Therefore materialists are claiming that we are no more than just a matter and electrochemical system.
In TED video, Ramachandran is basically supporting the brain chemistry argument which is the side of materialism. In brain, there are hundreds billions of nerve cells and they carry out each functions, such as consciousness or memory. And when these cells are damaged, the functions such as consciousness or memory will not work properly. In this video, the speaker gave 3 examples to explain brain chemistry.
First, he talked about Capgras syndrome. It's a disorder in which a person holds a delusion that a friend or a family member has been replaced by an identical-looking imposter. Usually when we think about the memory, or self-awareness, we think them as some kind of mentality. This makes us to think that we have minds which is what dualist says. However, if part of the brain that is associated with memory is damaged and we can't recall who the person is, then it proves that we don't actually have soul or mind but we have brain which is just a group of matter. This defeats dualists.
Second, he talked about phantom limb pain. According to his experiment, he had used mirror box to relieve phantom limb pain and move cut limb without phantom. The patient with phantom limb pain reflected his normal arm in the mirror. And when he moved the normal arm, he automatically moved phantom limb. Without looking at mirror, he couldn't move, but as soon as he looked at mirror again, he was able to move his phantom limb. This proves that by these kind of tricks, we can easily control the our brain and self-awareness. Many people believe that self-awareness is something that we think as mentality, however, if this is the case, we can't say we have minds, but self-awareness is just part of brain functioning which means there is no minds and souls in human being, so it defeats dualists.
Third, he talked about synesthesia. Synesthesia is condition in which stimulation of one sensory leads to automatic, involuntary experiences in a second sensory. In the video, he shows 2 shapes; a circle with smooth curve and another with croocked surface. Then people were told to decide which one would be booba and which one would be kiki. Then, most of them chose a shape with croocked surface a kiki. In this case, people were able to connect the word with the shape based on their experiences. In the brain sound and shape have cross-activated. However, when this part of brain is damaged again, then people won't be able to recognize things. Therefore this again shows that human beings are just no more than matters. Self-awareness that we hold to be mental stuff, is determined to be no more than one of brain functions which is just matter.
