Mind-Body Dualism: Leibniz, and Spinoza\'s

Mind-Body Dualism: Leibniz, And Spinoza's Approaches To The Problem

The Mind-Body problem is one that plagues philosophers, asking what the relationship is between the mind and the body? Human beings seem to exhibit distinct physical and mental properties. Their physical properties can be described by observation and describe appearance and physical ability, but their mental properties cannot be described by the same type of objective observation. The mind-body problem seeks to answer the question: is there a distinction between mental and physical properties? In order to answer this question, the mind-body problem looks at several distinct subcategories of questions, to further examine the relationship between mind and body. Those subcategories include, but are not limited to, the relationship between physical and mental states, the issue of consciousness, and the definition of the self. For the dualist, mental and physical states are both distinct and real. Not all dualists tackle this problem in the same manner, but the essence of dualism is that the mental and physical are distinct components of a being.

In order to understand how Leibniz solves the problem of mind-body dualism, one must have a greater understanding of his philosophy, as a whole, because Leibniz's view of both God and the universe impact his explanation of dualism. Leibniz considers every subpart of the universe to be reflective of the whole of the universe, which shows interrelatedness between all things. Specifically, Leibniz believes in a particular variety of dualism, parallelism, which suggests that the physical and mental realms may run in harmony with one another, but that they do not actually interact with one another. Leibniz, like many other parallelist dualist philosophers explains parallelism by referencing the divine.

Leibniz bases his system of knowledge on five fundamental principles are: the principle of contradiction (PC); the principle of sufficient reason (PSR); predicate-in-subject principle (PIS); principle of the best (PB); and principle of the identity of indiscernibles (PII). Furthermore, while Leibniz believes in the idea of God, he places some type of conditions on God's goodness. In other words, Leibniz ties the rationality of God's actions to the issue of moral evaluation. Therefore, God's actions and creations should not be praised because they are God's actions but because they are morally good. To come up with these conceptions, Leibniz reformulated divine freedom as exercising rational choice in contrast with absolutely independent will; God is constrained by morality. Furthermore, Leibniz concludes that there are independent moral/normative standards against which a person can evaluate God's actions. It places God inside a system with normative rules.

Leibniz wonders why God would create this world among all possible worlds and comes to the conclusion that this world is the most perfect of all possible worlds. Leibniz thinks that the contrast between the abundance of events and the meagerness of laws in the universe is what makes this universe better than any other possible universe. This shows how PSR and PB interact, and how tightly they are logically connected to one another. Furthermore, it is because this universe is the best of all possible worlds that God chose to create this particular universe. In contrast, others might suggest that it is because God chose to create this particular universe that it is the best of all possible worlds, but Leibniz believes that even God's actions must have a logical, rational basis.

Leibniz also discusses the notion of an individual substance that includes everything that has happened and will happen to it. Leibniz argues that the complete notion of an individual substance contains the traces of whatever happens in the entire universe. Therefore, every substance is a mirror of the whole universe from its own point-of-view. Knowing any individual substance completely allows a person to know a great deal about the whole universe, particularly the neighborhood of the substance.

Leibniz attempts to reconcile modern and ancient philosophies by suggesting that the knowledge of substantial forms is necessary in metaphysics, even if the scholastic belief that substantial forms are instrumental in explaining physical phenomena was misguided. He is dissatisfied with the idea of extension as the essence of bodies. Leibniz thinks that extension and its attributes such as size, shape, and motion are not sufficient to describe the substantiality of bodies. Instead, he believed that there had to be something soul-like in bodies to account for their substantiality. He rejected the primary/secondary qualities distinction. Instead, Leibniz felt that the extension account of physical substance was lacking, especially the activity and unity that a substance should have.

Although Leibniz's thoughts about individual substances would appear to commit him to a strict determinism that would undermine God's free will. In fact, the distinction between contingency and necessity makes Leibniz's proposed system appear similar to Spinoza's. However, Leibniz does not want to commit to strict determinism. He makes a distinction between certainty, which he looks at as hypothetical/comparative necessity, and necessity, which he looks at as absolute/logical necessity. Therefore, even though everything that happens is certain, everything that happens is not the result of an absolute necessity. In other words, the fact that something has happened does not mean that its opposite could not have happened, even if its opposite could no longer happen.

Spinoza's approach to dualism is much more complex than Leibniz's approach. Spinoza appears to reject dualism, while, at the same time seeming to embrace some of the components of dualism. Spinoza was distinctly not a dualist. He believed that a substance was a single thing, and that mind and body were both elements of that substance. Therefore, the dualist philosophy, which is that mind and body are distinct from one another, is not one that Spinoza endorses. However, he does agree with certain elements of dualism, and his philosophy is very similar to Leibniz's parallelist approach to dualism. After all, like Leibniz, Spinoza believes that mind and body do not casually interact, but run in parallel with one another.

Spinoza's philosophy has a different starting point than Leibniz and looks at individual existence as having a different relationship to God's existence. Spinoza believes in the idea of things being self-caused, and that those whose essence involves existence can be conceived only as existing. For Spinoza, causation on the level of existence is radical, as it involves an actual being causing or creating a possible or potential being to come into existence. Self-causation then is when one does not need an external cause for actualization. On the contrary, it is always actual because the actuality is part of its existence. This is how Spinoza differentiates God from other beings, because while people can conceive as other beings as not existing, it is impossible to conceive of God as not existing.

Rather than defining substance as mind and body separately, Spinoza looks at the substance of things as a whole, but a whole with distinct attributes. For him, substance is that whose conception does not require that of another thing, which makes substance both ontologically and epistemologically independent. Attributes are those things which the intellect perceives of substance as constituting its essence. A mode is that which exists in something else and that whose conception requires references to something else. Consciousness involves an awareness of all three: substance, attributes, and modes. Furthermore God, as an infinite being is a substance of infinite attributes, which are expressions of God's infinite existence. Therefore, there is no way to negate God's existence. This substance-attribute-mode trinity also allows Spinoza to differentiate between those things which are free and those which are necessary. Free things are those that exist through the necessity of their own nature and whose actions are determined by themselves, while necessary things are those things whose existence and acts are determined by another being.

Spinoza believes that substance is logically as well as ontologically independent. Substance must be able to be conceived without reference to anything else, and, therefore, must have unique attributes so that its conception will not contain a reference to another substance. This makes each substance one of a kind. This is the root of Spinoza's challenge to dualism, particularly Cartesian dualism, which separates the beings into minds and bodies. Spinoza expounds upon this idea to build the argument that there is actually one substance, God. He makes this argument by saying that substance has a unique essence and shares nothing common with another possible substance, and therefore cannot be the cause of another substance. Things can either exist as finite or infinite beings. However, for a substance to be finite, it would have to be limited by another substance of the same nature, an idea that Spinoza has previously rejected. Therefore substance exists as infinite. Spinoza clarifies this by explaining that human beings are likely to confuse substance with modifications and believe that those things seen in natural things are substances, but those are not substances, simply parts of substances. Modifications can actually be conceived as non-existent because their essence is included in something else. Modifications can even be conceived if they do not exist (imagined) because their essence is part of something else. As a result, each substance can have multiple attributes. In fact, an entity with an infinite essence will, by definition, have infinite attributes.

Spinoza builds upon the idea of an infinite God by going further and stating that absolutely infinite substance is indivisible. This is because, if it were divisible, and if each part would retain the nature of the infinite substance, which would result in there being more than one substance of the same nature, which Spinoza has already demonstrated is impossible. Moreover, if this substance were divisible in a way that meant that each part did not retain the nature of infinite substance that would result in the absolutely infinite substance ceasing to be. Because that is impossible, Spinoza comes to the conclusion that there can be no other substance but God.

If there can be no other substance but God, then extension and thought, if they exist, are either attributes of God or modes following from the attributes of God. Recalling that a substance can be a bearer of multiple attributes without being divisible, because an attribute is an essential property of substance and can be conceived through itself, it becomes clear that substances can have different attributes. Moreover, Spinoza suggests that the reality of a being goes parallel with its attributes. Therefore, an infinite being will have infinite attributes.

Examining Spinoza's reasoning about God, one sees further similarities between Leibniz and Spinoza. Spinoza comes to the conclusion that God cannot be conceived not to exist because existence is involved in his essence. Spinoza relies upon the principle of sufficient reason to come to the conclusion that there is always a cause for existence/non-existence. The only thing that could cause either God's existence or non-existence would have to be God. Leibniz also uses the principle of sufficient reasoning, but he uses it in a different manner. According to Leibniz, God is logically perfect, and, because he does not need anything else for his existence, nothing can prevent his existence.

Having established the existence of God, Spinoza goes on to look at what God would be described. He finds that God, as an infinite substance, cannot be bound by a finite body, shape, size, or extension. However, because God is the only substance, there cannot be corporeal bodies separate from God and created by God. If there is an extension, then it must be one of God's attributes, and therefore be infinite as well. Spinoza actually uses these propositions to declare that transcendent creation is possible, by establishing that substance cannot be produced or created from nothing, because existence is involved in its essence. Therefore, Spinoza rejects the transcendentalist approach. According to him, the main idea behind the transcendentalist approach is that corporeal substance is both finite and divisible, making it separate from God, who is both infinite and indivisible.

It is important to realize that their different conceptions of God mean that the philosophers also view morality in a very different manner. According to Spinoza God is the efficient cause of everything. He believes that intellect and will do not pertain to the nature of God. Instead, everything flows from God's nature, and not as a result of intellect or will. Therefore, God is not subject to any laws extrinsic to his own nature, including laws of morality. This point-of-view is very different than Leibniz's view, which suggests that even God's actions are guided by an overarching morality. Spinoza believes that intellect does not pertain to God's nature. If it did, it would be radically different from man's intellect, because God's intellect would necessarily come before those things of which he had knowledge, since God is prior in causality to all objects. If God's intellect was to be part of his nature, then it would not only be the cause of his essences, but also of the existences of things.

Spinoza's most difficult aspect of dealing with dualism comes when looking at the existence of finite things in the universe, if all things in the universe are extensions of God, who is, by definition, infinite. Spinoza comes to the conclusion that everything is determined by God's nature to exist and to exist in a determinate way. For him, there are two sides of Nature. First, there is the active, productive aspect of the universe, God and his attributes, from which all else follows. This side of Nature and God are identical. The other part of the universe is that which is produced and sustained by the active aspect. According to Spinoza, things could not have been produced by God in any other way than they were actually produced. God does not act from free will. In fact, according to Spinoza, God has never made a decision. God is the necessary, infinite, indivisible material substratum of all things, but not the paternalistic decision-maker he is conceived of as being in some philosophies. In other words, nothing in nature is contingent; all things have been determined from the necessity of the divine nature to exist and produce an effect in a certain way.

However, there are differences in the way that these things depend upon God. Some features from the universe follow from the absolute nature of one of God's attributes in a direct and unmediated manner. These are the universal and eternal aspects of the world, which do not come into or go out of being: the infinite modes. The general laws of the universe are among those attribute: geometry, physics, and logic. However, some things are more remote from God. These things include particular and individual things. They are affections of God's attributes or modes by which God's attributes are expressed: they are finite modes.

According to Spinoza, there are two causal orders governing the production and actions of particular things. First, they are determined by the general laws of the universe that follow immediately from God's natures. However, each particular thing is determined to act and to be acted upon by other particular things. Therefore, the actual behavior of a body in motion is a function not just of the universal laws of motion, but also of the other bodies in motion and rest surrounding it and which it comes into contact. This may not be a causal relationship, but it does imply interconnectedness between particular things.

One of the challenges that Spinoza things mankind faces in its conception of God is due to teleological reasoning. Traditionally, people have anthropomorphized both God and nature. However, conceiving of God as having an intellect like a human's, denies the infinite nature of God. It is erroneous to assume that God does things for a certain purpose or to achieve a certain end. Spinoza believes that the anthropomorophization of God has led to serious misconceptions regarding normative and aesthetic standards. Teleological reasoning leads to instrumental reasoning, because when men are convinced that everything in nature was created for the sake of mankind, then they evaluate things according to the degree of usefulness for men. Therefore, man's conception of morality is based upon how useful things are for human.