Spinoza is undoubtedly one of the greatest rationalist philosophers of the West. He developed the Cartesian theory of Substance into a full-fledged system of symmetry and perfection. To Spinoza there is only one Substance, God, and this he accepted in agreement with one of the aspects of the philosophy of Descartes. All things in the world follow for Spinoza from the supreme Substance, not as evolutes of it in the process of time, but in the manner of corollaries of a geometrical theorem. The universe is necessarily deduced from the one Substance as we deduce mathematical truths in our calculations and reasonings. Space, time and objects are all modes of the one Substance. Spinoza does not give time a separate reality; to him there is only eternity and time is only a mode of thought. Anticipating Hegel, as it were, he argues that the conclusions arrived at logically are not different from what exist really. He would agree with Hegel that logic and metaphysics are essentially one. To Spinoza thought and reality lose their distinctness and become one. Spinoza conceives the universe as an interrelated system in which every element is accommodated as an indispensable and necessary feature in the exact place assigned to it. The universe is a strictly determined whole and becomes rigid with the absence of any purpose or final aim directing it beyond itself. Spinoza makes thought and extension, the properties of the mind and matter in the philosophy of Descartes, the two attributes of the absolute Substance, and thus a greater consistency and method is seen in the system of Spinoza than in that of Descartes.
Substance is God, and, being independent, it is also infinite. All finite things are dependent on some other things. The Substance is its own determination, nothing else can determine it; it is not dependent on anything else. The great motto of Spinoza is that all determination is negation, and so the Substance is free from the determination of individuality or discreteness. God, being infinite, cannot be possessed of the psychological organs or be endowed with the volitional and intellectual functions known to man, which are valid only on a dualistic basis. Spinoza differs from Descartes in his view that God and the world are not two distinct principles. He merges God in the world and the world in God. Thus we get a pantheism where God is the world and the world is God. Students of Spinoza have, however, endeavoured to discover a transcendent aspect of the Supreme Substance and save him from the charge of pantheism.
Thought and extension are considered by Spinoza to be the two outstanding attributes of the supreme Substance, God. God has infinite attributes, but out of these only thought and extension are intelligible to man. These two attributes are everywhere, for they are inherent in the Substance which is infinite. There is no part of the Substance which is not defined by thought and extension. Spinoza is inclined to make each of these attributes infinite in nature, though on account of his endowing God with infinite attributes he is hesitant to make them absolutely infinite. The theory of parallelism which Descartes propounded finds a place again in Spinoza's system, though in a modified way. Spinoza holds that thought and extension cannot have interaction between themselves, for they are the inward and outward expression of one and the same process. One and the same entity appears as mind within and matter without. The order and connection of mental phenomena is not dissimilar to that of physical phenomena. The two laws run parallel to each other in their method and working. Mind and body are consequently considered to be modes of one process, having one law, and, thus, they cannot exercise influence on each other in any way. Thought and extension have equal reality and are subsistent in the infinite Substance and proceed from it as necessarily as mathematical deductions. There is no substance independent of God, Who is the supreme Substance and Whose attributes are thought and extension. In short, God, to Spinoza, is a thinking and extended being, which would mean that God is possessed of mind and body, though by God's mind and body Spinoza does not mean the mind and the body with which we are familiar, but the mental processes scattered over all space and time and the physical processes that constitute the stuff of the world. While Spinoza dismisses the dualism of substances admitted by Descartes, he accepts the same by making them attributes of the supreme Substance. The same difficulty remains, though the terminology in which it is expressed is different, and the rigour of the dualism is attempted to be overcome by its association with the One Substance.
Spinoza holds that Nature is in reality the one universal Substance, and its appearance as consisting of diversified phenomena is the result of our imperfect ways of looking at it. Everything in the world is an attribute or a mode of the eternal Substance, and its existence is the reality of all things. Spinoza goes beyond Descartes when he thinks that God and mind, too, are determined by the laws of mechanics. Spinoza makes strict determinism prevail in Nature. Purpose and design are to him delusions transferred to the objective universe by the limited vision of individuals. The will of God and the laws of Nature are not two different things, but mean the same thing. The laws are unchangeable and mechanical. There is a distinction, however, made by Spinoza between his conception of the supreme Substance and the ordinary view of substantiality or concreteness which many are likely to hold in regard to substance. By Substance Spinoza means essence or ultimate existence and not corporeal matter. He identifies his Substance, or God, which is the cause or origin, with what he terms Natura Naturans, as distinguished from the visible physical universe of diversified bodies, which is merely an effect and which he calls Natura Naturata. Spinoza's God has no will or intellect of the ordinary kind. He identifies God's Will with the totality of all causes and laws and God's Intellect with the totality of all minds in the universe. Thus, it appears that his God is in all ways the sum-total of individualities.
In the philosophy of the Vedanta, time is not a mode of any individual's mind but is necessarily valid to all minds. It is a part of ishvara-srishti and it can be called a mode of thought only when this thought is identified with the cosmic Will of Ishvara. All individuals are in time and no one creates time. Space and time are the necessary presuppositions of all perceptions. Even the ideas that arise in the mind of man are determined by the properties of space and time. Sensation, thinking, understanding and reasoning are all dependent on the universal properties of space and time. It is true that there is only eternity, and time is a relative appearance, but it has to be added here that this appearance is not the product of any individual's thought, but is the determining factor of all individual thoughts. Time belongs to the cosmos and hence it is an extramental reality. The Vedanta would agree with Spinoza that time is a mode of thought only when this thought is identified with God's Thought.
Spinoza's view that the universe is determined and rigid without any purpose or design directing it is not fully acceptable. The Vedanta makes a distinction between the universe as such which it calls ishvara-srishti, and the universe in relation to the individual which guides the processes of a secondary universe, which it calls jiva-srishti. When it takes into consideration the universe as such, the Vedanta would agree with Spinoza that it is determined and has no purpose beyond itself. For, the universe as it is in itself, independent of individual perceivers, is the body of Ishvara, and it is its own end. It has no other aim which may determine or direct its processes. God's Will is an eternal law, without a beginning and an end, and, as the universe as such is the very body of Ishvara, it must be eternally determined in its workings, allowing in no change, modification or amendment of any kind. Cosmic determination, relentless and immutable, is the law of the universe of Ishvara. But in the relative universe, which is what is observed by the individuals, there is purpose, design, aim, an ultimate goal. We cannot deny the fact of change in this universe. Change is movement and movement cannot be merely a chaotic changing of positions without a directing principle behind it. All change is movement towards an aim, a fulfilment in a higher principle, which is more inclusive and which transcends all the lower ones. The realisation of the highest perfection in the consciousness of what does not admit of any further transcendence is the ultimate directing principle of all movements seen in the world and the individuals. In other words, God-realisation or Self-realisation is the goal of life. Thus, there is a purpose in the workings of Nature, of which the different individuals are parts and which constitutes their environment with which they are inextricably bound.
Spinoza's view that God is a thinking and extended being requires a higher clarification and amendation according to the Vedanta. To say that God is thinking and is extended would be to make God a spatial entity. If God is in space, He is temporal and finite, and if He is not in space, He cannot be extended or have the need to think of anything. Thinking is always of something, and thinking in God can be accepted only when it is raised to the status of the activity of pure Consciousness in its own being and not considered as a faculty of mentation which requires an object outside it. God has to be really beyond space and time, for He is infinite. In the philosophy of the Vedanta, God and the Absolute have to be theoretically distinguished from each other. God is Ishvara, and the Absolute is Brahman. Ishvara, however, in His aspects of the Consciousness underlying the causal, the subtle and the gross universes is said to be defined by the characteristics of the universe. Thought and extension are not attributed even to Ishvara in the ordinary sense of these terms. No doubt, we speak of the Cosmic Idea or Will arising in Ishvara, but it is not an idea of any external object, not a will that determines anything outside itself. Ishvara is above space and time, for He is prior to the creation of the visible universe. Extension is divisibility and divisibility admits of change. Not only this; extension is an object of sense-perception. But Ishvara, or God, is not an object of the senses. When we attribute the characteristics of the temporal universe to Ishvara, we do not make Him an object of the senses, for He is infinite in nature. There is a great difference between the conception of Ishvara in the Vedanta and that of God in the system of Spinoza. Ishvara in the Vedanta is merely the objective counterpart of the individual's perceptions and experiences, logically deducted and accepted on the ground of the necessity of positing Brahman, or the Absolute, on the one side, and of taking for granted the visible universe of physical bodies on the other. The nature of Ishvara, therefore, is determined by the logical necessities arising from individual experience in the relative universe. What is experienced in individual perception is not necessarily a part of the Cosmic Reality, but the need for a satisfactory explanation of the implications of individual experience necessitates a transference of the contents of individual experience to the constitution of the Cosmic Reality. This transference, of course, is purely the result of individual necessity. Thought and extension are not considered to be essential aspects of Ishvara, but they are posited as necessary characteristics of His constitution merely to offer an explanation of the implications of human experience. It does not, however, mean that there is an 'objective' Ishvara absolutely independent of Brahman, mediating between the Jiva, or the individual, and Brahman, the Absolute. Else, the immediate salvation of the individual on the rise of perfect knowledge would be impossible and it would become necessary for every individual to get lodged in the state of Ishvara. Ishvara is Brahman itself visualised from the point of view of individual experiences. If there are no individuals, there cannot be an Ishvara, too; there would be only Brahman. But Spinoza's God has thought and extension as His necessary attributes. This God, thus, would be subject to spatial divisibility and become finite.
Spinoza merges God in the world and does not allow of a transcendent aspect of God. If the universe and God are one, the changes characteristic of the universe would be present in God, too. When God is subject to change and modification, He becomes finite, again. The Vedanta preserves the transcendent aspect of God, which remains unaffected by the changes that occur in the universe. Moreover, the universal changes are only apparent from the point of view of Reality, so that there is no possibility of God's being affected by the changes in the world. For the Vedanta, God is not exhausted in the world. His eternal aspect shines beyond the dust of the earth.
Spinoza identifies the Will of God with the totality of causes and laws and the intellect of God with the totality of minds in the universe. If God were but a sum total of all individual constitutions, the errors and defects present in them would also be present in God. The universe is characterised by ignorance, error, change, modification and death. The causes and laws in the universe are seen to be relative and not absolute. The minds of individuals are possessed of limited knowledge, and that too, of external things alone, and not of the essential reality of things. An accumulation of many finites cannot give us the Infinite. God is not merely an aggregate of the imperfect individuals and their laws. God is superior to the individuals, not only in quantity but also in quality. God, in the Vedanta, is not a sum total of individual beings, but the original or prototype consciousness, of which the individuals are limited and distorted reflections. As the defects of the reflections do not affect their original, so the defects of the individuals do not affect God – so holds the Vedanta. The individuals have a twofold defect: they are limited – this is quantitative deficiency; they are also distorted reflections – this is qualitative deficiency.
Spinoza denies free-will and establishes strict determinism. Human willing is determined by another cause, that by another cause, and thus ad infinitum. Man has the wrong notion that he is free, because he is unable to know the causes that direct his will. It is this ignorance on his part that is the cause of his being affected by censure, praise, pain, pleasure, etc. Spinoza compares the free-will that man seems to have to the thinking of a stone, if it were endowed with thought, that the positions which it occupies when it is thrown into space are chosen by its own free-will. In the philosophy of the Vedanta we have a blending together and a reconciliation of determinism and free-will. According to it, the universe as the manifestation of Ishvara is eternally determined by the Will of Ishvara. The past, present and future are all eternally fixed by His Cosmic Will. No individual, by any stretch of effort, can bring about the least change in this eternally determined universe of Ishvara's Will. But there is free-will. Free-will is the consciousness of independent individual agency which is given rise to by the Will of Ishvara when it manifests itself and works through the egoism of the individual. As long as this appearance of free-will is the sole director of the life of the individual, so long will the latter be responsible for its actions. The moment universal knowledge dawns in the individual, it rises above its notion of independent free-will and gets identified with the Will of Ishvara. In this universal identification consists the real freedom of the individual. The greater the approximation of the knowledge of the individual to the universal knowledge of the fact of the absolute supremacy of the Will of Ishvara, the greater is the freedom that the individual enjoys.
Spinoza's determinism has, of course, its higher ennobling side which attempts to free man from his petty individualism and unrestricted passions, and to make him understand that all events in the universe are parts of a perfection that is the whole. Spinoza feels that we would have no occasion to find fault with one another, to get angry or discontented, if only we could enter into the knowledge of the self-determined perfection of Nature and God. Guilt and error are results of ignorance of the universal perfection that reigns over the scheme of things, and Spinoza advises that though we punish evil-doers, we ought to have no hatred towards them, for they perpetrate evil on account of lack of real knowledge. We may add here that the punishment usually inflicted on evil-doers is more a measure against elements disturbing social peace than a process of educating the evil-doers, though there is no denying that many a time fear of punishment becomes an important factor in one's practice of virtue and goodness.
The great good that Spinoza tries to do by his theory of determinism is to enable man to bear the brunt of all pains and misfortunes with serenity, peace and an inner strength, and to be free from the emotions of joy when something desired takes place; for Nature is no respecter of persons or things; it is strictly impartial, and its love consists in law. God is both a kind mother and a stern father. This higher determinism is to be seen brilliantly expounded in the Vedanta, too. With such knowledge one becomes fit for the contemplation of the essence of things, which Spinoza calls the 'Intellectual Love of God'. It is intellectual love, rational love, love based on understanding, and not the emotional love which surges as a result of instinctive pressures. This divine contemplation requires as its pre-condition a knowledge of the greatness of God and the perfection of His Nature, which is manifest as the laws of the universe. 'All for the best' – this spirit should animate a person after he does intelligently all that he is capable of doing in the right direction, within the limits of his discriminative reason. Determinism, however, is not a licence for idleness or fatalistic surrender; on the other hand, it is the understanding of the great law that God alone is real and that He alone is capable of doing anything at all. Determinism is the higher phase of things, while an amount of free-will which makes itself apparent in man's life, though it may ultimately be discovered to be a chimera, rules the ways of man, and is indispensable for a well-governed and sensible life. Here we have to bring about a reconciliation between determinism and free-will. Spinoza's determinism which pays no heed to the fact of free-will and which makes the human soul a mode of God's Thought has, however, the sublime intention of raising man to God and divesting him of the wrong notion regarding his own importance in the world. The decision of the will and the determination of Nature coincide in the philosophy of Spinoza, for whom nothing higher than God or even equal to God can ever be. God cannot be loved unless His supremacy is known and accepted. If man, too, has some freedom on his part, then the state of God is not one of absolute freedom. Spinoza's love for God was intense and he did not wish that there should be anything in the world that would diminish this love, even in the least. Man's independent existence is, to him, an illusion. The truth is the oneness of man and his mind with Nature. From the interrelated system of Nature we are made to understand that man's love for God and God's love for man are both the same as God's love for Himself, for man is a mode of God. The highest good and the highest virtue, Spinoza makes clear, consist in the knowledge of God, the supreme Substance. This knowledge is attained in intuition.
Like Aristotle, Spinoza identifies the highest good of the individual with the highest good of the universe. And this highest good is the intuitive knowledge of God. Individualism and altruism, here, coalesce; selfishness is rooted out, for the one good of all is the love of God and the knowledge of God. In all these, Spinoza and the Vedanta are one.