This article is aimed at problematizing various obstacles that hinder or make it impossible for a cognizing subject to know the objective reality. Recognizing the impossibility of absolute truth, the fragility of our thinking becomes evident, always full of uncertainties and limitations, so we are interested in knowing the obstacles that arise in the process of knowledge. To identify and analyze them, we used the concept of epistemological obstacle that Gaston Bachelard developed to talk about the scientific spirit, adapting it to education through the concept of obstacle to knowledge. Obstacles to knowledge are presented as challenges to be overcome in order to get closer and closer to the objective truth, knowing that it will always be unattainable. To achieve this, it is necessary to identify such obstacles and submit them to criticism, a task that our students must learn and develop, which implies important challenges for critical thinking in education.