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The problem of universals – how can one thing in general be many things in particular – was solved by presuming that Form was a distinct singular thing but caused plural representations of itself in particular objects.
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He supposed that the object was essentially or "really" the Form and that the phenomena were mere shadows mimicking the Form that is, momentary portrayals of the Form under different circumstances. Form answers the question, "What is that?" Plato was going a step further and asking what Form itself is. The Forms are expounded upon in Plato's dialogues and general speech, in that every object or quality in reality-dogs, human beings, mountains, colors, courage, love, and goodness-has a form. What is the form really and how is that related to substance? The status of appearances now came into question. The answer was substance, which stands under the changes and is the actually existing thing being seen. The pre-Socratic philosophers, starting with Thales, noted that appearances change, and began to ask what the thing that changes "really" is. Plato used the terms eidos and idea (ἰδέα) interchangeably. The original meaning of the term εἶδος ( eidos), "visible form", and related terms μορφή ( morphē), "shape", and φαινόμενα ( phainomena), "appearances", from φαίνω ( phainō), "shine", Indo-European *bʰeh₂- or *bhā- remained stable over the centuries until the beginning of Western philosophy, when they became equivocal, acquiring additional specialized philosophic meanings. Plato uses these aspects of sight and appearance from the early Greek concept of the form in his dialogues to explain the Forms and the Good. The early Greek concept of form precedes attested philosophical usage and is represented by a number of words mainly having to do with vision, sight, and appearance. Nonetheless, the theory is considered to be a classical solution to the problem of universals. The theory itself is contested from within Plato's dialogues, and it is a general point of controversy in philosophy. Plato speaks of these entities only through the characters (primarily Socrates) of his dialogues who sometimes suggests that these Forms are the only objects of study that can provide knowledge. According to this theory, ideas in this sense, often capitalized and translated as "Ideas" or "Forms", are the non-physical essences of all things, of which objects and matter in the physical world are merely imitations. The theory of Forms or theory of Ideas is a philosophical theory attributed to Plato, that the physical world is not as real or true as timeless, absolute, unchangeable ideas.
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