If an alien could talk, could we understand it?

Wittgenstein believed that individuals need to have things in common, like experiences and points of view, if they are to understand one another. It is for these reasons that he remarked, “if a lion could talk, we could not understand him” – a lion’s experiences and points of view are likely so different to ours that they cannot mean what we mean even when they utter English words. If this is the case with lions, then what about intelligent extraterrestrials? If space-venturing aliens were to visit Earth, would we be able to strike up a meaningful conversation? In this chapter, I draw from Wittgenstein’s Tractatus Logico-Philosophicus and Philosophical Investigations to provide answers that give reason for both optimism and pessimism. I argue that although an alien’s language will not be logically closed off from human understanding (and vice versa), our forms of life may differ so considerably that we may never develop enough in common for mutual understanding to occur. I conclude with the following as a guiding principle to human-alien communication: ‘whereof our forms of life differ, thereof we cannot understand one another’. Unless something like evolution causes humans and aliens to develop similar forms of life, then we will not understand one another without a great deal of luck.