William of Ockham,''Razor''

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''Intuitive and abstractive cognitions'' :
http://www.angelfire.com/md2/timewarp/ockham.html
Intuitive or abstractive cognitions may be simple, composite, or complex. A simple intuitive cognition is an intuitive cognition of a singular thing. A simple abstractive cognition is an abstractive cognition of more than one thing, and thus is not 'proper' to a singular thing. A composite abstractive cognition may be 'proper' to a singular thing. A composite intuitive cognition of a singular thing may include multiple intuitions of that thing, and thus may also be 'proper' to a singular thing.
Intuitive or abstractive knowledge may be clear or unclear, specific or non-specific, definite or indefinite. In some cases, intuitive cognition may only be able to establish the existence of an object, without providing specific information about the nature of the object. Further inquiry concerning the nature of the object may occur by means of abstractive cognition. In other cases, intuitive cognition may not only be able to establish the existence of an object, but may be able to provide specific knowledge about the nature of the object
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All abstractive cognitions
-knowledge derived from experience,made possible by reflection upon experience-
depend upon prior intuitive cognitions
-sense experience of things-.
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Our knowledge of the existing world is contigent upon God's will,
for he can affect our intuitive cognitions whatever the facts may be.
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Predication occurs only if the predicate term of a sentence refers to the object referred to by the subject term,and if the predicate term refers to the object not by naming it,but by referring to some feature of it.
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Universals are not single properties common to many things,
but signs which have application to a number of things.
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An explanation involving fewer assumptions than an alternative explanation is preferable to the alternative.
-OCKHAM'S RAZOR :
entia non sunt multiplicanda praeter necessitatem (Latin, roughly translated as "entities must not be multiplied beyond necessity"), is the principle that "entities should not be multiplied unnecessarily" or, popularly applied, "when you have two competing theories that make exactly the same predictions, the simpler one is the better."-
http://en.wikipedia.org/wiki/Occam's_razor
In science,
Occam’s razor is used as a heuristic (rule of thumb) to guide scientists in the development of theoretical models rather than as an arbiter between published models.
In physics, parsimony was an important heuristic in the formulation of special relativity by Albert Einstein, the development and application of the principle of least action by Pierre Louis Maupertuis and Leonhard Euler,and the development of quantum mechanics by Louis de Broglie, Richard Feynman, and Julian Schwinger.
In chemistry, Occam’s razor is often an important heuristic when developing a model of a reaction mechanism.
However, while it is useful as a heuristic in developing models of reaction mechanisms, it has been shown to fail as a criterion for selecting among published models.
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(Franciscan,who later excommunicated by the Pope and his own order)
Ockham is known for his famous ''razor'',for his logic,and for his nominalistic and empirical viewpoint.
Living in the fourteenth century,he was the dominant figure in the movement away from Albertus Magnus,Thomas Aquinas,and John Duns Scotus,the great system builders of the thirteenth century.
Although he has been called the Hume of the Middle Ages,Ockham was not a sceptic.
Negatively,he undermined and rejected most of the metaphysics and a good deal of the natural theology of his contemporaries,but positively,he was a theologian who accepted the traditional Christian dogmas on faith and who preferred to accept them on faith alone rather than to argue for them on dubious philosophic grounds.
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