This article intends to answer the question of the ethics of hospitality, according to a specific objective, that of raising the hospitality to the rank of a philosophical question, with a view to delivering it, in these days, from the calculating game of politics in search of nationalistic votes, and the media spread of the dominant news on terrorism and migrants. Such an approach presupposes that the concept of hospitality fits into the field of the thinkable, that it is welcomed as a knowable host, figure, and object of knowledge. It is a question of asking for hospitality, the cousin of ethics, to think about the welcome and being-welcomed. One of the objectives of this text is to demonstrate that the concern for transnational solidarity is not a new phenomenon and that more than two centuries ago, Immanuel Kant, without forging the concept, already theorized certain issues. It is also true that most contemporary philosophers have addressed this important subject in one way or another. As the theory of international relations is increasingly shaken by the debate between constructivists and postmodernists (or deconstructivists), it seemed interesting to us, instead of studying the contribution to the understanding of transnational solidarity of the main political scientists involved to one or the other current, to look closely at the attempts at theorizing of the founder who is Immanuel Kant. Emphasis will be placed on the duty of transnational solidarity, which is to say on the ethical aspect.