Res High Educ https://doi.org/10.1007/s11162-018-9513-3 1 3 Efect of Critical Thinking Education on Epistemically Unwarranted Beliefs in College Students Kathleen D. Dyer 1  · Raymond E. Hall 2 Received: 4 April 2017 © Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract The degree to which students hold epistemically unwarranted beliefs, beliefs not founded on reliable reasoning or credible data, can be used as a measure of critical thinking skills. To this end, college students (n = 806) were surveyed at the beginning and end of a semester. Epistemically unwarranted beliefs were pervasive. Several sections of a critical thinking class that specifcally and directly addressed pseudoscience, taught by three diferent instructors, produced a large and signifcant reduction of those beliefs, but research methods classes and unrelated general education classes did not. Most likely to be reduced were beliefs in health pseudoscience and extraordinary life forms. Conspiracy theories were least likely to change. Demographic variables (gender, race, SES) were asso- ciated with beliefs at pre-test, but not related to reduction of belief as a result of the class. Similarly, academic indicators that suggest intelligence were related to belief at pre-test, but not change. The one exception was that reduction of belief in health pseudoscience was widespread in all groups at pre-test, but showed the greatest reduction among students with indicators of academic aptitude and achievement. We conclude that the educational approach of directly addressing pseudoscience is efective for changing beliefs, not just increasing knowledge, and that it works for most college students, not just a select subset. Keywords Critical thinking · Pseudoscience · General education · Epistemically unwarranted beliefs · Evaluation · Educational outcomes * Kathleen D. Dyer kdyer@csufresno.edu 1 Department of Child and Family Science, California State University, Fresno, 5300 N. Campus Drive, M/S FF12, Fresno, CA 93740, USA 2 Department of Physics, California State University, Fresno, Fresno, CA, USA