SHORT CASE FOR PANPSYCHISM
Below is a brief overview of how panpsychism is a real contender for the science of consciousness. For those who wish to have a more in-depth view then read the SEP entry (SEP on panpsychism) and the many excellent articles and videos on the panpsychism blog (click here).
BRAINS AND CONSCIOUSNESS
The standard explanation is that our brains create consciousness in some way. It is claimed that this mysterious consciousness is not the property of one structure in the brain but emerges somehow due to its functioning meaning that brain size is related to intelligence, sophisticated behaviour, and everything we associate with the 'higher consciousness' of man. However, this is not what we find in reality.
What we actually find is that a bee with a million times fewer neurones than the cow can talk to its hive mates in quantitative geometry and fashion hexagonal arrays whereas cows to do little except eat grass. Brain size has little to do with the sophistication of behaviour or social activities. A crow with no cortex and a nut-sized brain can use a tool to get food from a jar and has a pecking order in much the same way as an orang-utan with a very complex brain.
And what's more, organisms such as prokaryotes, protista, blood cells, and some fungi are unicellular and yet demonstrate tasks such as associative learning (Fernando, 2009), sensing their surrounding environment and achieving complex group decision making while living in complex social groups. All of this shows that many of the traits that we ascribe to the brain are not are in fact achieved by singular celled organisms without a brain, or central nervous system. More on cells consciousness can be found here.
Plants are far more complex than singular celled organisms and exhibit even more striking behaviour and abilities. Plants are complex organisms that live rich, sensual lives and are involved in communication with other plants. They do this by sending smell chemicals triggering specific reactions in other plants. Plants can sense gravity, and can even hear and also get jet-lag when traveling. They are aware of and respond to their environment such as a caterpillar munching it leaves will make it release defensive chemicals based on the sound alone. Research has also shown that plants can form memories, and they can even react to human anesthetics.
There is even a case to be made that individual particles are conscious but that involves a journey into quantum physics and is not for the faint-hearted. A look at how this is possible can be found here.
One major problem with materialism is found with the theory of how consciousness emerges from matter and many people have argued that emergentism and thus materialism is inconsistent. The arguments begin by asserting that a proton, say, is not conscious, but that a system (eg, myself with 5 x 10^28 protons) can be. This seems very implausible because the number would be a remarkable new constant of nature. Presumably it would have to be very large otherwise, we would certainly be in the situation where everything, except very tiny microscopic systems are conscious, which would essentially be equivalent to panpsychism. Then it appears hard to see how consciousness could exist for some number, N, of nucleons, but not for N-1. We would not expect such a fundamental difference come from such a small change of nucleons.
We could put the same point a different way. If we accept materialism it follows that some physical states of my body (ie, me) are happier than others. The same would be true if you removed a few of my molecules from my body (but not too many). There does not seem to be a reason to suppose that ‘suddenly’ this process would cease and that all states would become equally happy, which would imply that consciousness had dropped to zero. In the words of David Griffin :
“The difference between the proton and the psyche is one of degree and not of type (in an ontological sense). One who holds otherwise is a dualist, however, an odious description it may be.”
The argument that consciousness can not emerge from matter can be traced back to the Ancient Greek philosopher Parmenides, who argued that ‘ex nihilo nihil fit’ - nothing comes from nothing and thus the mental cannot arise from the non-mental. As Thomas Nagel's argued :
“there are no truly emergent properties of complex systems. All properties of complex systems that are not relations between it and something else derived from the properties of its constituents and their effects on each other when so combined.”
In fact, there are a number of popular arguments against materialism starting from a premise about an epistemic gap between physical truths about truths about consciousness and infer an ontological gap between physical processes and consciousness. Arguments of this sort include the conceivability argument, the knowledge argument, the explanatory-gap argument, and the property dualism argument. Of course, materialists reply that epistemic premises do not entail the ontological conclusion. Nevertheless, before materialists can conclude that their case is won they must solve the problem of emergentism since positions like panpsychism have all the benefits but none of the problems of explaining emergentism.
EVOLUTION, NON-EMERGENCE AND MATERIALISM
The most popular empirically based argument for panpsychism stems from Darwinism and is a form of the non-emergence argument. This argument begins with the assumption that evolution is a process that creates complex systems out of pre-existing properties but yet cannot make “entirely novel” properties  . William Kingdon Clifford argued that:
“… we cannot suppose that so enormous a jump from one creature to another should have occurred at any point in the process of evolution as the introduction of a fact entirely different and absolutely separate from the physical fact. It is impossible for anybody to point out the particular place in the line of descent where that event can be supposed to have taken place. The only thing that we can come to, if we accept the doctrine of evolution at all, is that even in the very lowest organism, even in the Amoeba which swims about in our own blood, there is something or other, inconceivably simple to us, which is of the same nature with our own consciousness" (Jonathan, 2015)
ARGUMENTS FROM INSTRINSIC NATURE
Many philosophers and scientists have argued that everything must have an intrinsic nature. They argue that while the objects studied by physics are described in a dispositional way, these dispositions must be based on some non-dispositional intrinsic attributes, which Whitehead called the “mysterious reality in the background, intrinsically unknowable”  . While we have no way of knowing what these intrinsic attributes are like, we can know the intrinsic nature of conscious experience which possesses irreducible and intrinsic characteristics. Arthur Schopenhauer argued that while the world appears to us as representation, there must be 'an object that grounds' representation, which he called the 'inner essence' (das innere Wesen) and 'natural force' (naturkraft), which lies outside of what our understanding perceives as natural law.
Philosophers such as Galen Strawson, Roger Penrose (1989), John Searle(1991), Thomas Nagel (1979, 1986, 1999) and Noam Chomsky (1999) have said that a revolutionary change in physics may be needed to solve the problem of consciousness  . Galen Strawson has also called for a revised "realistic physicalism" arguing that,
"the experiential considered specifically as such—the portion of reality we have to do with when we consider experiences specifically and solely in respect of the experiential character they have for those who have them as they have them—that ‘just is’ physical". If this line of reasoning holds then consciousness must be intrinsic to the nature of the world.
If this line of reasoning holds then consciousness must be intrinsic to the nature of the world which is exactly what panpsychism maintains.
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Jonathan, E. (2015). Is Consciousness Only A Property Of Individual Cells? Journal of Consciousness Studies, 12(4), 60-76.
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