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Part III. Neutral Monism

Spinoza's Neutralism

Philosophy of Baruch Spinoza
Baruch (Benedictus) Spinoza was one of the most original and independent thinkers in the history of philosophy. He wanted to present his system modo geometrico (which in Latin means: following the example of geometry) starting from simple and unquestionable axioms and rules of reasoning and proceeding to more complex theorems. Spinoza's attempt provoked an important methodological discussion that resulted in the conclusion that philosophy cannot be built in the same way as geometry or an exact science. Despite the rejection of Spinoza's geometrical method by contemporary philosophy, many of his philosophical ideas are still influential.

Spinoza was the first modern philosopher claiming that God is everything in the universe. The view that everything is God is called philosophical pantheism. Spinoza claimed that God was the only substance in the universe and that it had two kinds of characteristics: material and mental. Hence, whatever we call matter is really a material characteristic of God; also the soul (or other mental characteristics) is a mental aspect of God.

Generalized view of neutral monism
For Spinoza the only substance in the universe was God. However, Spinoza's general idea of neutral monism (or neutralism) can be presented also in a more general way which does not involve his pantheism.

Neutral monism acknowledges that materialism and dualism are both right that we perceive certain things (like tables and trees) as a material substance. It also agrees with idealism and dualism that we perceive other things (such as thoughts and feelings) as a mental substance. But neutralism sees the question of how the mental and the material substance interact as unsolved by dualism. Therefore, neutralism rejects every conception in philosophy of mind discussed above. Instead, it postulates the existence of a single substance which underlies both material and mental characteristics.

Spinoza's version of neutralism has an interesting feature. Every version of neutralism claims that neutral substance can be perceived only in terms of its material or mental attributes. Yet, according to Spinoza, this is just because of the limitations of human beings. Spinoza claims that neutral substance has infinitely many attributes (that is why he identifies it with God) and other beings, for instance angels, could have more kinds of ways to perceive it.

Russell's new version of neutral monism
While Spinoza was a pantheist, Bertrand Russell (1872-1970) was one of the leading exponents of philosophical atheism. Rejecting the idea of God Russell endorsed a very different version of neutralism than the one presented by Spinoza. However, he agrees that there is only one substance that is neither mental, nor material.⁶

Russell's view introduces us to contemporary analytical thinking, which is our main focus in Part B of the course.⁷ Now I will present only the bare bones of Russell's version of neutralism.

Let us take into account a certain characteristic such as color. We can describe a color from the first person perspective as a certain mental phenomenon. For instance, you recognize the colors yellow and red as being warm whereas blue as cold. This way we perceive colors in their mental aspect. But a physicist can define colors as certain wavelengths -- this is their physical aspect. In his neutral monism Russell claims that everything can be perceived in these two aspects (under two kinds of descriptions) material and mental. Every sound, smell, every object that we can know in the universe must be perceivable from the first person perspective as a mental object. It is necessary because if any object had not been perceivable at least as an object of your thoughts (what Berkeley calls an idea), then you could not know about it. On the other hand, every idea must have a material aspect to it (in this sense Russell was very close to materialism). Even such subjective feelings as your pains must have some material basis for them to occur; some of the neurons in your body must be stimulated to produce the feeling of pain. Therefore nothing is merely physical or merely mental but every object has these two aspects.

In the second part of the 20th. Century many materialists endorsed the elements of Russell's view while trying to give priority to the material substance. For example the double aspect theory, which is a version of materialism, claims that material substance can be perceived in its two aspects, one of them material, the other mental. It seems difficult to justify calling this kind of theory a form of materialism; Russell's reference to neutralism seems more accurate.

In Part B of the class we shall read an article by Thomas Nagel who subscribes to another version of materialism, called non-reductive materialism. Nagel tries to accommodate within a materialistic model some intuitions that led Russell towards neutral monism.