Philosophical Foundations: From Ancient Greece to Kant
Socrates, Plato, and Aristotle: Foundations of Western Thought
Socrates and Plato, considered founders of Western philosophy, believed in the possibility of acquiring objective, necessary, and universal knowledge. This knowledge, they argued, must be unchanging and permanent, distinct from the fluctuating perceptions of our senses. Plato justified this concept by proposing the existence of two realms: the world of Ideas (inaccessible to the senses) and the sensible world. The world of Ideas, according to Plato, is the true reality, perfect and eternal. He believed we once had knowledge of this realm but forgot it upon entering the imperfect, sensible world.
Aristotle agreed with Plato on the existence of objective knowledge, independent of sensory perception. However, he diverged from Plato’s dualistic view. Aristotle, a realist, criticized Plato’s “unnecessary duplication” of reality. The main difference lies in their understanding of substance. For Plato, substance is the Idea, while for Aristotle, it is the actual individual, particular and subject to change. This “first substance” is composed of matter and form. Matter can be proximate or remote, with remote matter resembling Anaximander’s Apeiron. Form is the essence, the “second substance” or species, and is eternal, though inseparable from the individual. It is the object of science, as taught by Socrates and Plato.
Parmenides reduced reality to a static, immobile sphere of Being, while Heraclitus saw everything as being in constant flux. Plato attempted to reconcile these opposing views by distinguishing between the Sensible World, characterized by change, and the Intelligible World, populated by eternal and immutable Ideas. Aristotle introduced the concepts of act (Being) and potency (a peculiar form of non-being), suggesting that motion is the transition from potency to act.
Physics was a central concern for philosophers like Empedocles, Anaxagoras, and the atomists. Parmenides considered sensory knowledge deceptive, as his philosophy of Being implied a denial of nature. Plato believed nature could not be subjected to rigorous science, which should focus on Ideas. Aristotle, however, valued nature as a source of scientific knowledge. He criticized earlier philosophers for focusing solely on material causes (e.g., Thales on water, Heraclitus on fire, Anaximenes on air, Empedocles on fire, air, earth, and water) or, like Plato, on material and formal causes but in separate worlds. Aristotle proposed four causes: material, formal, efficient, and final.
For Aristotle, body and soul are one substance, related as matter and form. This view led him to reject Plato’s doctrine of reincarnation. The soul, being the principle of all activity in living beings, cannot pre-exist or exist beyond death. While Plato distinguished three parts of the soul, Aristotle defended its unity, placing it throughout the body, but assigning it different functions: nutritive, sensory, and thinking.
Greek philosophers, since the Presocratics, generally undervalued sensory experience as a source of knowledge. Parmenides believed the senses provide misleading knowledge, while reason offers reliable truth. Plato considered only knowledge of Ideas as real, with the senses being a constant hindrance. Aristotle, however, took the opposite view, valuing the empirical world and experience. He also opposed the Pythagorean use of mathematics as the sole key to understanding nature.
Plato’s ethics were intertwined with his Theory of Ideas, contrasting with the relativism and skepticism of the Sophists. Aristotle, while rejecting the Theory of Ideas, agreed with Plato that there is a supreme end: happiness, the key to which is reason.
Both Plato and Aristotle believed the state is superior to the individual and that humans are inherently social beings who can only fully develop within a state. Aristotle considered the ideal of individual autarky absurd.
Kant and the Influence of Ancient Philosophy
The Stoics, along with Socrates, Plato, and Aristotle, significantly influenced Kant. Kant, like Descartes and Aristotle, was a metaphysical idealist and a rationalist. However, he also incorporated elements of empiricism, influenced by Hume. Kant sought a balance between rationalism and empiricism, similar to Aristotle. He believed virtue leads to happiness, culminating in “Perpetual Peace” achieved through citizenship, representing the highest good. This aligns with Aristotle and Plato’s views on virtue, while Socrates equated happiness with wisdom. Kant, unlike Plato and Descartes, denied innate ideas. He saw humans as social and political beings, a view shared by many earlier philosophers. Kant believed in universal humanity, while Descartes and Plato posited the existence of universal knowledge. Kant argued that moral action is guided by duty, contrasting with Descartes (moral action guided by reason) and Plato (moral action fulfilling one’s duties). Kant rejected the idea of the Philosopher King, unlike Plato and Aristotle. He believed, like Socrates, Plato, and Aristotle, that ethics and politics should be intertwined. Kant favored a Republican government, like Plato, while Aristotle and Socrates preferred aristocracy. Kant criticized democracy, similar to Plato, Aristotle, and Socrates.
Kant emphasized the cosmopolitan state, advocating for the coexistence of diverse cultures, a view shared by the Stoics but rejected by the Epicureans. Kant held a materialistic view of the body-soul connection, similar to the Stoics, while Plato and Descartes viewed the soul as spiritual and immortal. Kant believed the state’s function is to ensure freedom, contrasting with Aristotle (educating citizens for happiness) and Plato (ensuring citizens’ virtue). For Kant, things consist of individuals plus sensations, while for Plato, things are imitations of Ideas. Regarding the active and passive, Kant saw the individual as active and the external world (matter) as passive. Aristotle similarly viewed form as active and matter as passive. Plato considered Ideas active and things passive, while the Stoics saw the universal logos as active and matter as passive. Kant believed sociability arises from a social pact, while Aristotle saw it as inherent in human nature, and Plato argued that humans need to socialize to develop fully. Finally, Kant believed all beings have equal rights as citizens, while Plato advocated for a social hierarchy in determining citizenship.
Kant’s Enduring Legacy in Modernity
Kant’s philosophy remains highly influential in modernity. He argued that peace is not natural for humans, who emerged from a state of war through a social contract. He believed that modern states exist in a state of war and require a new contract to achieve lasting peace. Kant’s rationalism has influenced modern science, emphasizing not only observation but also understanding the underlying causes of phenomena. His moral philosophy, advocating for the pursuit of the common good, continues to resonate today. Finally, Kant’s emphasis on cosmopolitanism, the coexistence of diverse cultures within a single society, is particularly relevant in our increasingly interconnected world, especially evident in countries like Spain.