Last week, we examined Spinoza's metaphysics, looking at how his radical reinterpretation of the philosophical terminology of substance, attribute and mode produces a new vision of reality. According to Spinoza, only God can be called a substance – that is to say, an independently existing being – and everything else is a mode of this single substance. But what does this mean for us?
One of the central questions of philosophy is: what is a human being? And this question can be posed in a more personal way: who am I? As we might by now expect, Spinoza's view of the human being challenges commonsense opinions as well as prevailing philosophical and religious ideas. We are probably inclined to think of ourselves as distinct individuals, separate from other beings. Of course, we know that we have relationships to people and objects in the world, but nevertheless we see ourselves as autonomous – a view that is reflected in the widelyheld belief that we have free will. This popular understanding of the human condition is reflected in Cartesian philosophy, which conceives human beings as substances. In fact, Descartes thought that human beings are composed of two distinct substances: a mind and a body.
For Spinoza, however, human beings are not substances, but finite modes. (Last week, I suggested that a mode is something like a wave on the sea, being a dependent, transient part of a far greater whole.) This mode has two aspects, or attributes: extension, or physical embodiment; and thought, or thinking. Crucially, Spinoza denies that there can be any causal or logical relationships across these attributes. Instead, he argues that each attribute constitutes a causal and logical order that fully expresses reality in a certain way. So a human body is a physical organism which expresses the essence of that particular being under the attribute of extension. And a human mind is an intellectual whole that expresses this same essence under the attribute of thinking.
But this is not to suggest that the mind and the body are separate entities – for this would be to fall back into the Cartesian view that they are substances. On the contrary, says Spinoza, mind and body are two aspects of a single reality, like two sides of a coin. "The mind and the body are one and the same individual, which is conceived now under the attribute of thought, now under the attribute of extension," he writes in book two of the Ethics. And for this reason, there is an exact correspondence between them: "The order and connection of ideas is the same as the order and connection of things." In fact, each human mind involves awareness of a human body.
This way of thinking has some important consequences. One of the most obvious is that it undermines dualistic and reductionist accounts of the human being. Descartes's mind-body dualism involves the claim that we are, in essence, thinking beings – that the intellectual should be privileged above the physical, reason above the body. Conversely, modern science often regards the human being as primarily a physical entity, and attempts to reduce mental activity to physical processes. In Spinoza's view, however, it is incoherent to attempt to explain the mental in terms of the physical, or vice versa, because thinking and extension are distinct explanatory orders. They offer two alternative ways of describing and understanding our world, and ourselves, which are equally complete and equally legitimate.
Another important consequence of Spinoza's account of the human being is his denial of free will. If we are modes rather than substances, then we cannot be self-determining. The human body is part of a network of physical causality, and the human mind is part of a network of logical relations. In other words, both our bodily movements and our thinking are constrained by certain laws. Just as we cannot defeat the law of gravity, so we cannot think that 2 + 2 = 5, or that a triangle has four sides.
Spinoza's criticism of the popular belief in free will is rather similar to his analysis of belief in miracles in the Theologico-Political Treatise, which we looked at a few weeks ago. There, we may recall, he argued that people regard events as miraculous and supernatural when they are ignorant of their natural causes. Likewise, human actions are attributed to free will when their causes are unknown: "That human freedom which all men boast of possessing … consists solely in this, that men are conscious of their desire and unaware of the causes by which they are determined." For Spinoza, belief in free will is just as much a sign of ignorance and superstition as belief in miracles worked by divine intervention.
