Spinoza is seen as a philosopher whose work is often obscure and difficult to understand, unlike, for example, Descartes whose texts are well written with clear and distinct concepts. Especially Spinoza’s Ethics is considered opaque, not only now but also by readers in his time. Nonetheless his ideas are still important today, which becomes apparent if one gives them a somewhat anachronistic interpretation that relates them to present discussions.
Take for instance Part I of Spinoza’s Ethics. Spinoza had read the philosophical works by Descartes very well. He had even written a course on Descartes’s philosophy for his friends and followers. However, Spinoza did not agree with Descartes. Especially he rejected his dualistic world view. I think that many readers of this blog will know that according to Descartes the world is made up of two basic substances: matter and mind. Although these substances could interact with each other (in man this happened via the pineal gland in the brain), they were independent of each other. It was not what Spinoza thought. Let’s see what he writes in the beginning of his Ethics, where he expounds his world view. Spinoza has built up his Ethics as a mathematical theory. This involves that he starts from definitions and axioms and that with the help of them he proves his propositions. Since substances are what make up the world, he starts his works with discussing them and their characteristics. First he gives eight definitions. For us the most important are:
III. By ‘substance’ I mean that which is in itself, and is conceived through itself: in other words, that of which a conception can be formed independently of any other conception.
IV. By ‘attribute’ I mean that which the intellect perceives as constituting the essence of substance.
Next Spinoza presents seven axioms. Then with the help of the definitions and axioms he develops his propositions. Until now I assumed that there are several substances, but in proposition V Spinoza clearly rejects Descartes’s dualism of matter and mind by concluding from his definitions and axioms:
There cannot exist in the universe two or more substances having the same nature or attribute.
Or as the last sentence of the proof of this proposition reads:
[T]here cannot be granted several substances, but one substance only.
All this is rather vague. However, I think that Spinoza’s view becomes clear, if we see it as a first version of what nowadays is presented as the dual aspect theory of body and mind.
One of the main current ontological discussions is on the nature of the relation between mind and matter, and especially between mind and body, in case we study the problem how man is constituted. Are mind and body one? Are they separate? If the former, what then is mind exactly, if we assume as undisputed that man has a body anyway? If the latter, how do mind and body relate? Since Spinoza rejects the dualism of mind and body as two substances, we can ignore the latter question. But what is mind then given the presence of body (matter) anyway and Spinoza’s monist view that there is only one substance? A view accepted by many philosophers today is that man is a material being and that the mind is a kind of epiphenomenal effect emerging from the human matter. Others, like me, prefer a dual aspect view on man, which says that man can be considered and studied in two different ways: as a biological body or as a conscious and thinking mind, although in the end man is both together. In other words, man has two aspects: a bodily aspect and a mental aspect, which are two sides of the same coin, so to speak. This is now what Spinoza wants to say, too, I think. We have seen already that – against Descartes – Spinoza maintains that there is one substance, which we can interpret that way that there is only one “stuff” that makes up the world. But how must we conceive such a substance? That’s why Spinoza has introduced the concept of attribute. As defined by Spinoza it’s a difficult concept. However, following Lord in his Spinoza’s Ethics – which is an explanation of and introduction to the book – we can say that “attributes are the different ways in which a substance can be perceived. ... An attribute is the substance itself, as perceived in a certain way” (p. 21; italics Lord). According to Spinoza, two attributes are relevant for man: Extension and thinking. Also for Descartes extension and thinking are relevant for man. The difference between both philosophers is, however, that for Descartes extension and thinking are separate substances, but for Spinoza they are two different attributes of the one substance that exists in this world.
Once we know this I think that the analogy between Spinoza’s view on the world and the dual-aspect theory is clear, certainly if you know that the latter is also called dual-aspect monism. Spinoza’s attributes are nothing but what we now call “aspects” and his extension and thinking are what the dual-aspect theory calls “matter” and “mind”. Even more, also Spinoza speaks often of matter and mind in this way. Seen thus, Spinoza’s view is actually quite simple.
I want to add yet one remark. According to Spinoza, the one existing substance has an infinite number of attributes. So in fact, his theory is a multi-aspect theory. But because only two attributes are relevant to man, we can ignore it.
Spinoza, Benedict de, The Ethics, on http://www.gutenberg.org/cache/epub/919/pg919-images.html)Lord, Beth, Spinoza’s Ethics. Bloomington, Indiana: Indiana University Press, 2010. Also available online: http://www.faculty.umb.edu/gary_zabel/Phil_100/Spinoza_files/guide%20to%20spinozas-ethics.pdf