Epistemological solipsism as a route to external world skepticism

There are almost 8 billion human beings on the planet. Some of these I know personally. They are my colleagues, neighbors, friends, and family members. Others are distant strangers, most of whom I will never meet. I take it for granted that all of these beings are, like myself, sentient. I presume that they have opinions and aspirations, hopes and dreads; that they experience intense pleasures and sharp pains, along with dull aches, surprise, simple satisfaction, ennui, and deep longing; that they can reflect, contemplate, learn, interpret the world and themselves, and act on those interpretations. Certainly, I do not think my fellow humans are mere automata, mindless entities that somehow manage to give off the appearance of sentience. In fact, psychologically speaking, it is extraordinarily difficult for me to take seriously, even as a remote possibility, that these others might somehow fail to be sentient. Still, I can ask: Do I know that these others are sentient? Do I know that I am not alone in the universe?1 Epistemological solipsism (sometimes abbreviated to solipsism) is the view that I do not know that other minds exist. One way of motivating this view draws from the possibility that others might appear to be sentient whilst altogether lacking a mental life. On one line of reasoning, if I cannot rule out that this possibility obtains, then I do not know that other minds exist, even if the others around me are in fact sentient.2 Epistemological solipsism does not enjoy a central place in contemporary philosophical theorizing.3 The reasons for this are no doubt complex, but I would conjecture that the following is one contributing factor: epistemological solipsism is presumed to be easily refutable, for instance, on broadly abductive grounds. For presumably the best explanation of why others seem to be sentient is that they are sentient.4 If solipsism can be ruled out this easily, then perhaps solipsism doesn’t warrant a central position in philosophical theorizing. I would conjecture than an additional factor which contributes to solipsism’s neglected status is the fact that solipsism is sometimes taken to be merely a special instance of external world skepticism. External world skepticism is, at a minimum, the view that vast swathes of your empirical beliefs about the world outside your mind fail to amount to knowledge. Unlike solipsism, external world skepticism enjoys a highly central place in contemporary epistemology; indeed, its refutation is sometimes taken to be the raison d’être of epistemological theorizing.5 If solipsism’s