Galef received a BA in statistics from Columbia University. In 2010 she joined the board of directors of the New York City Skeptics. She co-founded and became president of the nonprofit Center for Applied Rationality (CFAR) in 2012. The organization also gives workshops to train people to internalize and use strategies based on the principles of rationality on a more regular basis to improve their reasoning and decision making skills and achieve goals. She was elected a fellow of the Committee for Skeptical Inquiry in 2015.
In 2009, Galef began co-hosting the Rationally Speaking Podcast with the philosopher of science Massimo Pigliucci. Their first episode was released on February 1, 2010. The show hosted conversations with public intellectuals such as Neil deGrasse Tyson, Lawrence Krauss, James Randi, and Peter Singer.
Galef frequently speaks on rationality and moderates debates at skeptic conferences. She gives public lectures to organizations including the Center for Inquiry and the Secular Student Alliance. From 2010 to 2015, she was a speaker for the Northeast Conference on Science and Skepticism.
Galef began writing the blog Measure of Doubt in 2011 with her brother, as well as writing for Religion Dispatches and Scientific American. Since April 2015 she has been the sole host of the Rationally Speaking podcast. Galef's activities as a writer, podcaster and president of CFAR are mentioned by the The Atlantic, The Verge, and NPR.
In 2014, she wrote several articles and recorded several short videos for Big Think, some of which are part of the Big Think Mentor's workshops. Subsequent to her exposure with Big Think as an expert on the topic of rationality, she was interviewed in 2014 by Forbes, Fast Company, and The Wall Street Journal. In particular her idea of keeping a "surprise journal" received attention, which is one of the techniques Galef uses to record incidents where her expectations were wrong, in order to recognize personal faulty assumptions that expose and counterweight the "bias blind spot". According to Galef, it can be easier to adjust internalized beliefs by framing the new evidence as a surprise.
In February 2016, Galef delivered a TED talk on, "Why you think you're right — even if you're wrong", encouraging critical self-skepticism and prioritizing coming to the correct viewpoint using "scout mindset" instead of working to ensure your current viewpoint is seen as correct with a "soldier mindset". The talk was covered by NPR's TED Radio Hour in November 2016.
Julia Galef often explains common confusions and popular misconceptions of rationality. Frequently she distinguishes "epistemic rationality" from "instrumental rationality". She describes epistemic rationality as a way of reasoning according to logic and the principles of probability theory to form beliefs and conclusions. In contrast, she describes instrumental rationality as a decision-making process in which people choose the action that maximizes their expected utility, whatever their goals are.
Galef popularized the concept of Straw Vulcan, the incorrect perception about rationality as a way of thinking that denies emotions such as love and lacks appreciations for beauty. It refers to the fictional character Mr. Spock (a half-Vulcan) in Star Trek, who is often seen as a poster child for this caricature of rationality. On the contrary, Galef argues that Mr. Spock's failure to adjust his thinking, even though he experiences that humans do not always make rational decisions, is a case of irrationality. In 2011, Galef gave a talk on this subject at Skepticon.