III. Some Popular Arguments for Dualism
A. The Argument from Religion
"A major source of dualistic convictions is the religious belief many of us bring to these issues. Each of the major religions is in its way a theory about the cause or purpose of the universe, and Man's place within it, and many of them are committed to the notion of an immortal soul -- that is, to some form of substance dualism. Supposing that one is consistent, to consider disbelieving dualism is to consider disbelieving one's religious heritage, and some of us find that difficult to do. Call this the argument from religion" (from Churchland, Matter and Consciousness).
Weaknesses with the Argument from Religion:
1. Attempts to decide scientific questions by appeal to religious orthodoxy has a sorry history.
("That the stars are other suns, that the earth is not the center of the universe, that diseases are caused by microorganisms, that the earth is billions of years old, that life is a physicochemical phenomenon; all of these crucial insights were strongly and sometimes viciously resisted, because the dominant religion of the time happened to think otherwise.")
2. Even if we grant that there is an afterlife, it is not clear that the afterlife cannot be accommodated within a materialist framework. That is, it might be possible for a materialist to believe in life after death.
B. The Argument from Introspection
"A more universal consideration is the argument from introspection. The fact is, when you center your attention on the contents of your consciousness, you do not clearly apprehend a neural network pulsing with electrochemical activity: you apprehend a flux of thoughts, sensations, desires, and emotions. It seems that mental states and properties, as revealed in introspection, could hardly be more different from physical states and properties if they tried. The verdict of introspection, therefore, seems strongly on the side of some form of dualism" (from Churchland, Matter and Consciousness).
Weakness in the Argument from Introspection
1. This argument assumes that our faculty of inner observation or introspection reveals things as they really are in their innermost nature. This assumption is suspect because we already know that our other forms of observation -- sight, hearing, touch, and so on -- do no such thing. (For instance, we cannot detect, just from looking at water, that it is actually composed entirely of tiny molecules.)
C. The Argument from the Parapsychological Phenomena
"Finally, parapsychological phenomena are occasionally cited in favor of dualism. Telepathy (mind reading), precognition (seeing the future), telekinesis (thought control of material objects), and clairvoyance (knowledge of distant objects) are all awkward to explain within the normal confines of psychology and physics. If these phenomena are real, they might well be reflecting the superphysical nature that the dualist ascribes to the mind. Trivially they are mental phenomena, and if they are also forever beyond physical explanation, then at least some mental phenomena must be irreducibly nonphysical" (from Churchland, Matter and Consciousness).
Weaknesses in The Argument from the Parapsychological Phenomena
1. "It is not entirely clear that such phenomena, even if real, must forever escape a purely physical explanation."
("The materialist can already suggest a possible mechanism for telepathy, for example. On his view, thinking is an electrical activity within the brain. But according to electromagnetic theory, such changing motions of electric charges must produce electromagnetic waves radiating at the speed of light in all directions, waves that will contain information about the electrical activity that produced them. Such waves can subsequently have effects on the electrical activity of other brains, that is, on their thinking. Call this the 'radio transmitter/receiver' theory of telepathy." It's not that we have any reason to think this particular theory is true; rather, this just shows that the existence of parapsychological phenomena doesn't automatically suggest dualism.)
2. Parapsychological phenomena are very dubious.
There is not a single parapsychological effect that can be repeatedly or reliably produced in any laboratory suitably equipped to perform and control the experiment.