None of them vanished; the area used for all the 14 leprechauns in The Vainishing Leprechaun remains the same when the paper is swapped to form 15 leprechauns. However, notice that parts of the legs or body of some of the leprechauns in the arrangement of 14 leprechauns are not there anymore in the one for 15 leprechauns? For example, the first leprechaun on the left gets shorter when you rearrange it to Leprechauns the vanishing. All this area is used in creating the 15th leprechaun. This means that none of the 14 leprechauns vanished. One was created out of some areas from the other leprechauns.
Also, the allegory with the prisoners killing the one who escaped could be an example of the natural of mankind’s “unwillingness to change”, unless there is a need to. In the prisoner’s example, when the one who escaped could not recognise anything in the real world, he was forced to make sense of it and integrate it into his reasoning. Likewise, wars provided the ultimate incentive for major breakthroughs in technologies such as weapon systems and long range communications, all of which benefit us today. Furthermore, were it not for the Soviets, the space race would not have happened, and mankind would not have every set foot on the Moon. Now that there is not major source of competition, the incentive for discovery to show the scientific capability of USA is literally not existent, since there is no other nation to threaten their “throne” as the most scientifically and technologically advanced nation. The result? Now USA does not even have their own fleet of spacecraft that can fly, and have to rely on Russian rockets. Therefore we can conclude that unless there is a major incentive to change, man will not change.