Solipsism is the problem that Husserl faced in his early phenomenology which had the problem of understanding intersubjectivity, for instance inCartesian Meditations. One of the main things that Heidegger was trying to do in Being and Time was to get around this problem, with his idea of the immersion of dasein in the mitsein: there-being in with-being. But Husserl solved the problem with his later generative phenomenology by getting rid of bracketing, and using the world as a horizon upon which all phenomena are seen. Heidegger probably got this solution form Husserl but I am not sure about this. Scholarship on the late works of Husserl is just now coming out. However, much of this is no longer a problem so much now that we know about mirror neurons and have a good idea about “theory of mind” and folk psychology. In other words there are built in mechanisms that are social from the beginning, like the idea that speech makes babies move with micro movements that tune their whole body to the conversation happening in the room, and also we now are pretty sure that grammar comes from children who when they learn a language with their peers will simplify the grammar if it is irregular. And for instance there is the tickle response that you cannot invoke yourself. Lots of recent research shows how the social responses that bridge the gap between separate psyches are built in from the beginning, and not just based on acculturation. For instance the study of Wolfchildren shows that they cannot really learn language after a certain age.