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Modal Logic Quotes

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Modal Logic Quotes

“Also, I say that although things other than God are actually contingent as regards their actual existence, this is not true with regard to potential existence. Wherefore, those things which are said to be contingent with reference to actual existence are necessary with respect to potential existence. Thus, though "Man exists" is contingent, "It is possible for man to exist" is necessary, because it does not include a contradiction as regards existence. For, for something other than God to be possible, then, is necessary. Being is divided into what must exist and what can but need not be. And just as necessity is of the very essence or constitution of what must be, so possibility is of the very essence of what can but need not be. Therefore, let the former argument be couched in terms of possible being and the propositions will become necessary. Thus: It is possible that something other than God exist which neither exists of itself (for then it would not be possible being) nor exists by reason of nothing. Therefore, it can exist by reason of another. Either this other can both exist and act in virtue of itself and not in virtue of another, or it cannot do so. If it can, then it can be the first cause, and if it can exist, it does exist—as was proved above. If it cannot [both be and act independently of every other thing] and there is no infinite regress, then at some point we end up [with a first cause].”

PhilosophyLogicTheologyMetaphysicsOntologyModal Logic
Book:A Treatise on God as First Principle
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“Moreover, if there were two natures having necessary being of themselves, neither would depend upon the other for existence and consequently no essential order would exist between them. One of them, therefore, would not belong to this universe, for there is nothing in the universe which is not related by an essential order to the other beings, for the unity of the universe stems from the order of its parts. Here it is objected that inasmuch as each is related to the parts of the universe through the order of eminence, this suffices for unity. To the contrary: One is not so ordered to the other, for a more perfect existence characterizes the more eminent nature. Nothing however is more perfect than a being having necessary existence of itself. What is more, one of two is not ordered to the parts of the universe, because if the universe is one, then it is characterized by a single order and this obtains where there is but one first. Proof: If you assume there are two first natures, since there is a dual term of reference, the nature next to the first has no unique order or dependence and the same is true of each subsequent nature. And thus through the whole universe there will be two orders, and hence two universes. Or else where will be an order only to one necessary being, but not to the other. If one proceeds reasonably, then, it seems he ought not to postulate anything for no apparent need, or whose entity is not clearly revealed by reason of some order to other things,—for, according to Physics, Bk. I, more than one thing should not be postulated where one suffices. Now we show there is a necessary being in the universe from the uncausable, and this in turn from what is first in causing, and the latter from what is caused. But from these effects there is no apparent necessity for assuming several first causing natures; furthermore, this is impossible, as will be shown later in the fifteenth conclusion of this third chapter. Therefore it is not necessary to assume that there are several things which are uncaused and necessarily exist. With reason, then, they are not postulated.”

PhilosophyReligionTheologyMetaphysicsOntologyModal Logic
Book:A Treatise on God as First Principle
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