Fostering critical thinking among senior high school students in Colombia has been an unfulfilled goal. This undesirable situation has multiple causes: “critical thinking” has become a mere slogan and its meaning and scope have not been clearly specified despite being widely used in the different levels of the education system. Furthermore, the strategies designed to teach critical thinking lack creativity, reinforce rote learning and the sheer repetition of logic rules besides misallocating the goal of reasoning and argumentation by focusing only on rhetorical persuasion. Textbooks and core literature in critical thinking suggest that a critical thinker is someone who always has plenty of arguments to defend her beliefs besides being ready to address even destructive criticism. By contrast, critical rationalism emphasizes the importance of a humble approach, acknowledges error, and portrays a critical thinker as someone who is ready to test her most beloved theories against experience and to reject them in the light of the facts that contradict her beliefs and certainties. We consider that a pedagogical approach enriched with fallibilism might be central for a better education and endorse these views with the results of a case study conducted in Manizales, Colombia, which shows that teaching the basics of logic and argumentation by using the central tenets of critical rationalism fosters critical thinking among senior high school students