The Platonic Legacy: What Plato Gave Western Culture
From Plato Western thought (especially religious thought: Christian and Islamic philosophy and modern Judaism) inherits the following:
1) Idealism or The Forms: the concept of "The One" (or what Christians, Muslims, modern Jews call "God") as that eternal something which combines “the good”, “beauty” and “Truth” into a single, eternally unchanging essence, or Idea or cosmological Ideal (rather than “person”).
2) That everything in this corporeal, sensual world (the world we perceive thru our senses) is a "fallen" (a term Plato uses metaphorically) version of this Ideal (see "The Allegory of The Cave").
Mind-Body Dualism: the
mind/psyche/soul has a separate existence from the physical body. The soul
“descends” (metaphorically) and returns to from the Ideal/The One at the birth
and death of body. Knowledge of the Ideal, knowledge of Truth,
or "true knowledge", comes via this
offers the first, oldest argument that one’s physical body and soul are separate
entities and that one lives on after the other has died.
Therefore: Taken together, this relationship implies that sensual knowledge – knowledge gained via the senses – can only be of this fallen world and is therefore faulty, “fallen”, and removed from the ideal. Knowledge of Truth cannot be gained from this world but only through intelligibility. In philosophy this intelligible knowledge is generally conceived of as math, or reasoning which holds to the fundamental premises of mathematical proofs. In religion, such access is through prayer and faith: ignoring this sensible/sensual knowledge of this “fallen” world and perceiving The One through the “mind’s eye” or “the soul”.
Plato thus conceives of knowledge as innate to the human psyche/soul: it arrives with the soul at birth (or conception). This concept is fundamentally at odds, however, with nearly all modern empirically data concerning the mind and learning.
This refers, essentially, to the adaptation and spread of Platonic thinking throughout other cultures, philosophies and places. In the context of Western culture, it refers more specifically to this adaptation by first Hebrew and then Christian, and then Islamic, theology.
In a nutshell, Plato’s philosophy spread with the spread of the Greek Empire and, most importantly, had a profound effect on, first, Jewish theology. This influence continued with the rise of the Romans and then became a centerpiece of Christian theology. Many of the central elements of Christian philosophy/theology are, in fact, explicitly originally rooted in Plato, not the Bible. See Philo Of Alexandria (20 BC - 50 AD), Plotinus (ca. AD 204–270), and to a degree, Justin Martyr (100-165).
Most importantly see Augustine of Hippo (St. Augustine) (also see here) (354-430), through whom Neo-Platonism -- and thus Plato -- is translated into Medieval Christian doctrine. Augustine On Plato, From Confessions, book VII. A good focused discussion of the relationship is here.
Wait, I Thought The Jews or Christians Invented the Immortal Soul? See Platonic Dualism
It is almost impossible to now conceive of Christianity or
Islam without recourse to Platonic terms and concepts. From Jewish,
Christian and Islamic Neo-Platonists we get the concepts that:
-- God is the eternally true, eternally good from which all other truth and goodness emanates; he is not a person or being, but an eternal essence of combined Truth, Goodness and Beauty
-- These eternal truths, this eternity and truth, exists outside of, away from, detached from, the physical world, in the realm of the Ideal.
-- Our souls emanate from this Good or God
-- This relationship of soul to The Good or God is the source of human truth and knowledge of any Ideal form, including virtue, love etc.
-- We must uncover or remember eternal truths that we know innately, through our soul’s relation to The Good or God (for the Greeks, this occurs thru logic, but for the religious this occurs thru meditation or prayer)
-- Sensible knowledge – knowledge gained through our senses – is faulty, and true knowledge is gained through contemplation of The Good: a combination of logical (logos) and spiritual “thinking”
-- We must not carried away by the pleasures of this world (sex and drugs and rock 'n' roll) because this will keep the soul from returning to an eternal life with The Form Of The Good, or in non Platonic terms "God".