Rene Descartes’ “mind-body problem” stemming from his substance dualism thesis was left, for the most part, undeveloped. Though he affirmed that mind and body were two separate and distinct substances causally interacting, the process of how the interaction takes place was left up to the reader to interpret and discern. In attempts to rescue Descartes his successors – philosophers of his era, responded by either offering an explanation of the causal relationship of mind and body or removing the interaction altogether. In this essay, I will focus on Malebranche’s occasionalism and Spinoza’s monism as available and potential solutions to the mind-body interaction problem. For each, I will relate a general understanding of the idea. I will conclude by defending Spinoza’s monism theory as the more persuasive of the two.
First, I will begin by summarizing the main points of occasionalism. Malebranche claims that “it is God who does everything in all things (217).” This follows from the idea that finite beings have no causal efficacy; no power to bring about any movement and unable to cause anything to happen. According to Malebranche, God is the “universal cause”, his will is what moves bodies and what allows us to perceive their motion (218). In other words, there is no direct causal interaction between mind and body. Instead, God acts as the mediator, moving the body according to the person’s will and generating the appearance of direct causal interaction to be perceived by his creatures. The individual’s willing of an action provides God with the occasion to move or change a body.
To better convey this idea, I think it beneficial to provide an example. Movement in our body appears to be causally related to our will to move. If I reach out to open the door, for example, it seems that the act of willing that I open the door, and me actually taking hold of the doorknob are directly connected. It also seems that touching the doorknob provokes a sensation that engenders the ideas of coldness and smoothness in my mind. However, Malebranche would contest and claim that my volition to take hold of the doorknob merely provides God with an opportunity, better yet, an occasion to exercise his power and efficacy of will to move my body. My volition to open the door is not the true cause of my arm extending and my hand taking hold of the doorknob, rather, the true cause of my movement is God. Additionally, the ideas of coldness/smoothness are put in my mind by God, “I grant that man wills and that he determines himself… but it is because God gives him all the ideas and feelings that are the motives by which he determines himself (220).” These ideas aren’t communicated to the mind by means of touching the doorknob, rather God puts the ideas about the doorknob in our minds.
Malebranche uses an example of a ball striking another to express a similar notion. He states that though it seems apparent that our will/mind is the cause of the movement of our bodies or other bodies, if we examine our reason we will realize that “the mind will never conceive that a body, a purely passive substance, can in any way whatsoever transmit to another body the power of moving it (216).” Simply put, bodies are passive and inert, they do not and cannot move unless they are moved first, God is what moves and continuously conserves them from place to place. And as previously mentioned, the same happens for ideas. God is the means of communication between minds and bodies.
Now, I will touch on Spinoza’s Monism. Spinoza, rather than assign causality to God, approaches the mind-body problem by removing it all together, simply by denying substance dualism. According to Spinoza, there are no two distinct substances as Descartes had claimed. Instead, he argues, there is but one substance, God or in a broader sense, nature. Humans, animals, and objects are not substances, they are modes of substance. Before going further, it’s appropriate to clarify what Spinoza means when he uses the term “substance” and “mode”. By substance, Spinoza means, “that which is in itself and is conceived through itself (E1d3).” A substance is then something that does not depend on anything outside itself for its existence, it is self-sufficient. That is to say, that God was conceived through himself and exists independently of anything else. That leads to the concept of modes. Modes are the properties of one substance, also referred to as affections (E1d5). So, people, animals, and objects are all properties of this one substance that manifests itself as any and all of the three (and anything that exists in the physical world) throughout different places in space.
These ideas, along with “attributes” is relevant to the mind-body interaction problem as explains why we perceive there to be two substances rather than one as Spinoza would have us consider. Now, attributes are the essential characteristics by which we conceive of a substance in a particular way, they are the essence of a thing, it’s what it is to be that kind of thing (E1d4). Now, according to Spinoza, “the more reality or being a thing has, the more attributes it has (E1p9).” This is relevant to our discussion because two attributes ascribed to God are thought and extension (E2p1-2). These two attributes, through which we perceive the world are what Descartes referred to as two distinct substances. Spinoza is saying that extension and thought are not substances, rather they are two ways in which we perceive the substance that is God of which people, animals, and things are only properties of. Because substance has an infinite number of attributes, “each of which expresses eternal and infinite essence (E1p11)”, we get people, animals, and things.
Though both occasionalism and monism address the mind-body interaction problem it is my opinion that of the two, monism is the most persuasive. I will now address my concerns with occasionalism. Malebranche proposes a way of understanding that there isn’t a direct interaction. God is the mediator between the two distinct substances that wouldn’t otherwise interact or be able to communicate with each other. To provide an example I will recycle a metaphor previously utilized in my essay on Descartes’ argument for dualism. Now, if we liken the mind to electricity and the body with an appliance and we understand these “substances” to be distinct from each other, as Descartes would affirm, then we understand that there must in some way be a connection that allows for the appliance to interact with electricity. Descartes himself did not offer the answer as to how, but Malebranche, through occasionalism is saying, in keeping with the metaphor, that God is the hand that moves the plug of the appliance and inserts it into the outlet full of electricity. A necessary act because there is no causal efficacy between the two to achieve movement/change and maintain this interaction on its own.
I struggle to accept this is a viable solution. For one, Malebranche is maintaining Descartes dualism. He is affirming, like Descartes that they are truly separate and distinct and as a result need a mediator. This is conflicting given that Descartes also claims that God is, “a certain substance that is infinite, independent, supremely intelligent, and supremely powerful… (51).” If God is infinite than he is complete and lacks nothing. But if God lacks nothing, then there can be nothing that is not God, no other substance should exist. If it could exist aside from God than God would be lacking in something. Malebranche maintains the dualist position and in doing so subjects his theory to a contradiction.
In contrast, Spinoza claims that there is only one substance, manifested in different modes. This doesn’t just address the mind-body interaction problem, it completely removes it. There is no distinction to be made, and so there is no interaction that needs to be mediated or explained. What is considered two substances, mind, and body are one in the same, one substance, perceived by the senses as through different attributes, namely, thought and extension.