- Extension (metaphysics)
In
metaphysics , extension is, roughly speaking, the property of "taking up space".René Descartes defines extension as the property of existing in more than one dimension. For Descartes, the primary characteristic ofmatter is extension, just as the primary characteristic ofmind isconsciousness . This can be contrasted with current conceptions in quantum physics, where thePlanck length , an almost unimaginably tiny quantity, represents reaching that distance scale where, it has been theorized, all measurement seemingly breaks down to that which can be subsumed at this scale, as distance only, or extension.For
John Locke , extension is "only the space that lies between the extremities of the solid coherent parts" of a body. It is the space possessed by a body. Locke refers to the extension in conjunction with 'solidity ' and 'impenetrability ,' the other primary characteristics of matter.Extension also plays an important part in the philosophy of
Spinoza , who claims that substance (that which has extension) can only be limited by substance of the same sort, i.e. matter cannot be limited by ideas and vice versa. From this principle, he determines that substance is infinite. This infinite substance is what Spinoza callsGod , and it possesses both unlimited extension and unlimited consciousness.The property of extension has not played a significant role in philosophy roughly since the time of
Kant . Kant maintained a distinction between the mind and the body, differentiating space as the realm of the body andtime the realm of the mind. He makes only cursory mention of "extension," however, and no philosophers have dealt extensively with the topic since Kant's writing.Infinite Divisibility
Extension or Quantity, when divided and divided further infinitely, cannot reach the point of zero quantity. It can be divided into very small or negligible quantity but not zero or no quantity at all. Using mathematical approach, especifically goemetric models, Leibnitz and Descartes discussed the infinite divisibility of extension. Actual divisibility may be limited due to unavailabilty of cutting instruments but its possibility of breaking into smaller pieces is infinite.
Compenetration
Compenetration refers to occupation of two or more extensions in the same place at a given time. This, according to scholastic philosophers, is impossible. Only spirits or spiritualized matter can occupy a place occupied already by an entity (matter or spirit).
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