Existence and Life
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Existence and Life
Life is a characteristic of organisms that exhibit certain biological processes such as chemical reactions or other events that results in a transformation. Living organisms are capable of growth and reproduction, some can communicate and many can adapt to their environment through changes originating internally.[1] A physical characteristic of life is that it feeds on negative entropy.[2][3] In more detail, according to physicists such as John Bernal, Erwin Schrödinger, Eugene Wigner, and John Avery, life is a member of the class of phenomena which are open or continuous systems able to decrease their internal entropy at the expense of substances or free energy taken in from the environment and subsequently rejected in a degraded form (see: entropy and life).[4][5] An entity with the above properties is considered to be a living organism, hence, a 'life form'. However, not every definition of life considers all of these properties to be essential. For example, the capacity for evolution is sometimes taken as the only essential property of life; this definition notably includes viruses, which do not qualify under narrower definitions as they are acellular and do not metabolize. A diverse array of living organisms can be found in the biosphere on Earth. Properties common to these organisms—plants, animals, fungi, protists, archaea and bacteria—are a carbon- and water-based cellular form with complex organization and heritable genetic information. They undergo metabolism, possess a capacity to grow, respond to stimuli, reproduce and, through natural selection, adapt to their environment in successive generations. So far, there is no evidence of extraterrestrial life. In common usage, existence is the world of which we are aware through our senses, but in philosophy the word has a more specialized meaning, and is often contrasted with essence. Philosophers investigate questions such as "What exists?" "How do we know?" "To what extent are the senses a reliable guide to existence?" "What is the meaning, if any, of assertions of the existence of categories, ideas, and abstractions." The word "existence" comes from the Latin word 'existere', meaning to appear or emerge or stand out. The word 'exist' is certainly a grammatical predicate, but philosophers have long disputed whether it is also a logical predicate. Some philosophers claim that it predicates something, and has the same meaning as 'is real', 'has being', 'is found in reality', 'is in the real world' and so on. Other philosophers deny that existence is logically a predicate, and claim that it is merely what is asserted by the etymologically distinct verb 'is', and that all statements containing the predicate 'exists' can be reduced to statements that do not use this predicate. For example, 'A Four-leaved clover exists.' can be rephrased as 'There is a clover with four leaves.' This philosophical question is an old one, and has been discussed and argued over by philosophers from Plato, Aristotle, through Avicenna, Aquinas, Scotus, Hume, Kant, Kierkegaard and many others. In mathematical logic existence is a quantifier, the "existential quantifier", symbolized by ∃, a backwards capital E. To symbolize "Four leaf clovers exist," mathematicians would first define predicates, P(x) = "x is a clover" and Q(x) = "x has four leaves", and then form the well-formed formula (∃x)(P(x) and Q(x)).
YouTube | February 28, 2009
