This book provides the foundations of trust amidst radical uncertainty. Specifically, it addresses the question of under what condition it is possible to trust relative strangers. As the first logical investigation of its kind, the book breaks with many preconceived ideas we have about trust and the scientific method that leads to its clarification. It builds on the insight that, contrary to widespread belief, it is not risk but freedom that is most fundamental for explaining trust. In fact, trust is the giving of freedom, out of freedom, and one's consciousness of the potential risks involved merely disturbs one's ability to trust. The book makes the twofold normative claim that any legitimate scientific preoccupation with trust must necessarily include the concept of freedom in its account, and that theories of trust that run against the logical prerequisites of freedom are a-priori falsified. It presents a theoretical proposal that makes sure that trust, instead of being constructed as a passive and functional "illusion" of natural love, is understood as the necessary product of an active reason that is oriented towards developing human autonomy.