Although Leonard Peikoff (and Objectivism) disagrees entirely with Plato, he admits the genius of the philosopher. Plato was the first to gather all the “suggestions” that had been produced by the pre-Socratics and the sophists, in addition to all the teachings of Socrates in a coherent whole. In doing so, he created philosophy as it is, for better or for worse.
As for Socrates, true knowledge for Plato (his best and most famous disciple) must concentrate not on particulars, but on universals. Remember that the pre-Socratics wanted to understand change and multiplicity. Universals are immutable, eternal and indestructible truths; they are the “one in the many,” the common denominator unifying the multiplicity of entities. Particulars, in turn, are the many entities we see around us, changing all the time in every respect and every moment, forming the “world of flux” of Heraclitus.
Moreover, Parmenides, Heraclitus, and practically all the pre-Socratic philosophers, including the sophists, have agreed that the senses deceive; they make the world seem to change when it is really stable, or immobile when it is fleeting and unstable, or they show one thing to you and another to me — that is the world of appearances, the physical world of particulars apprehended by the senses. Universals, therefore, can not be physical. They must be immaterial entities apprehended only by the superior faculty of man: his intellect.
In a word, universals are perfect.
But nothing in this world is perfect. If something changes, it is not perfect, because if it were, it would just stand still, it would not lack anything. Yet we have acquired the concept of perfection somehow. How? There must be a world of perfect universals that we have contemplated at some point before this life: the World of Ideas or Forms. The World of Forms is the true one; the world we live in is just an imitation, a projection of the real world.
To explain the origin of our world, Plato tells the myth of the Demiurge, a tale that is the forerunner of many religious visions. This divine entity sorted and organized matter, molding it using the perfect Forms as an architect to produce as much order and harmony as it could; that was the real source of the natural laws we observe in the world. This is the most primitive version of what later became the “argument of design” for the existence of God.
The forms are therefore logically related to each other within an integrated system. The sciences are, in fact, attempts to discover the structure of this system, first by assuming certain relations between forms and then trying to deduce their consequences.
Now, says Plato, this represents a problem: unless we can validate the basic premises of each science, all our knowledge will remain hypothetical. We need some fundamental point from which we can deduce the axioms of the various individual sciences: a fundamental form. Plato called this ultimate form the “Form of the Good,” since the good is that which everything seeks. Metaphysically, it is the purpose of all existence, the purpose of the universe. Epistemologically, it is the fundamental axiom of all knowledge.
To understand the Form of the Good, one must transcend the intellect and have an intuition, a vision that brings total illumination, a sort of clairvoyance that, if not personally attained, cannot be explained by anyone else. This, of course, is mysticism, and Plato may be considered the father of mysticism in Western philosophy.
“Our world is not real.”
This unhappy idea of a genius will take on many guises throughout the history of thought, and will eventually morph into the subjectivism and relativism we see in our era.