Plato’s Idealism
Plato’s theory of knowledge, which Aristotle says is different from that of Socrates, was based on the idea that the object of knowledge must be permanent, eternal, and since nothing under the sun is permanent, we must seek stable knowledge outside this fleeting and deceitful world of material things. When Diogenes ridiculed the theory of Ideas, by saying he could see the cup, but not ―cupness,‖ Plato retorted that that was because he had eyes to see, but no intellect. And it is true that merely to base oneself on sense-perception is not enough. It is necessary to go from the particular to the universal. The fundamental flaw here is to think that the generalisations of the intellect can stand on their own, divorced from, and counterposed to, the material world from which, ultimately, they are derived. Marx and Engels in The Holy Family explained: in the philosophy of Idealism, the real relations between thought and being are stood on their head, ―for the absolute idealist, in order to be an absolute idealist, must necessarily constantly go through the sophistical process of first transforming the world outside himself into an appearance, a mere fancy of his brain, and afterwards declaring this fantasy to be what it really is, i.e., a mere fantasy, so as finally to be able to proclaim his sole, exclusive existence, which is no longer disturbed even by the semblance of an external world.‖ (MECW, Vol. 4, p. 140.) The sophistical trick whereby this is done was wittily explained in the same work: ―If from real apples, pears, strawberries and almonds I form the general idea ‗Fruit,‘ if I go further and imagine that my abstract idea ‗Fruit,‘ derived from real fruit, is an entity existing outside me, is indeed the true essence of the pear, the apple, etc., then—in the language of speculative philosophy—I am declaring that ‗Fruit‘ is the ‗Substance‘ of the pear, the apple, the almond, etc. I am saying, therefore, that to be a pear is not essential to the pear, that to be an apple is not essential to the apple; that what is essential to these things is not their real existence, perceptible to the senses, but the essence that I have abstracted from them and then foisted on them, the essence of my idea—‘Fruit.‘ I therefore declare apples, pears, almonds, etc., to be mere forms of existence, modi, of ‗Fruit.‘ My finite understanding supported by my senses does of course distinguish an apple from a pear and a pear from an almond, but my speculative reason declares these sensuous differences inessential and irrelevant. It sees in the apple the same as in the pear, and in the pear the same as in the almond, namely ‗Fruit.‘ Particular real fruits are no more than semblances whose true essence is ‗the substance‘—‘Fruit.‘ (Ibid, pp. 57-8.) Far from advancing the cause of human understanding, the idealist method does not take us a single step forward. Only a study of the real, that is to say, material world, can deepen our understanding of nature and our place in it. By directing men’s eyes away from ―crude‖ material things towards the realm of so-called ―pure‖ abstraction, the idealists played havoc with the development of science for centuries. ―By this method one attains no particular wealth of definition. The mineralogist whose science was limited to the statement that all minerals are really ‗the Mineral‘ would be a mineralogist only in his imagination. For every mineral the speculative mineralogist says ‗the Mineral,‘ and his science is reduced to repeating this word as many times as there are real minerals.
Spinoza's Monism
Spinoza, by the strength of reason, and with the very limited scientific results available to him, arrived at one of the greatest hypotheses of all time. Breaking with Descartes, with his notion of a body without a soul and a soul without a body, he advanced the idea that body and mind are two attributes of one and the same thing. The universe is not composed of mind and matter, as alleged by Descartes’ dualism. There is only a single Substance, which contains within itself all the attributes of thought and being. It is infinite and eternal, and possesses all the potential to give rise to the abundance of phenomena we see in the universe.
Spinoza gives this Substance the name of “God”. But in reality, to make God equal to nature is to abolish God – a fact which was not lost on Spinoza’s enemies when they accused him of atheism. In Spinoza’s universe, infinite and eternal, and therefore uncreated and unbounded by heaven or hell, there is no room for a separate deity. Indeed, there is no room for anything whatsoever except Substance, which is just another way of saying nature.
Thus, in a strange way, the philosophy of Spinoza, despite its idealist appearance, is the real point of departure for materialism in the dialectical, that is, non-mechanical sense of the word. All that is necessary is to substitute the word ‘matter’ for ‘God’ and we get a perfectly consistent materialist position.