Many people claim that they have been abducted by aliens. But, however real theexperience might have seemed, it is the product of dreaming caused by sleepparalysis. In such sleep, the dreamer might hear strange noises, see flashing lights orstars, and sense shaking and juddering. Some dreamers also feel that they are beingturned in their beds. All of these experiences match those of people reporting supposedabduction by aliens. This type of sleep phenomenon is fairly common, being experiencedby three out of ten people. In that sleep paralysis explains the sensations reported byeveryone who claims to have been abducted by aliens, we can conclude that aliens havenot come to Earth and abducted people. Which of the following is an underlying assumption of the argument above?