from something that that thing is not. Anselm made a similar point in Chapter II of the Proslogion (Anselm 21). What it means to be contingent is that it is possible to be something else, and if it is not something else, then there is a reason sufficient to explain it such that it is that and not something else.For example, let me illustrate the point by assuming that a chair is a contingent being. From now on, whenever I use chair it shall be synonymous with a contingent being. So, a chair by definition may or may not be. Leibniz claims here that if there is a chair there, there is a reason sufficient to explain it. Why is it a chair and not something else? Well, perhaps we can think of several reasons, but if the reasons are not sufficient, then it still could be something else. The "something else" is what I mean by its opposite. Anything else that a chair is not is contained within the meaning of "opposite of a chair."Therefore, after arguing that contingent beings fall under the principle of sufficient reason, Leibniz argues that there cannot be an infinity of contingent reasons, by the law against infinite regress (Leibniz 238). Therefore, he concludes that if contingent beings exist, it necessarily follows that there is a necessary being which exists. If an infinity of contingent explanations be allowed, then it follows that there is no reason sufficient to explain the contingent being. Yet, a contingent being without sufficient reason to explain it was shown to be absurd. The law against infinite regress as it applies to the principle of sufficient reason is the same as saying a partial explanation is no explanation at all because there could be at some point introduced a further explanation which negates what had been previously thought. An infinite regress would never fulfill the demands of the principle of sufficient reason. Therefore, given that contingency depends upon necessity such that there is no infinite regress, ther...
