This lecture discusses key ideas from the 20th century philosophical short story writer, essayist, and poet Jorge Luis Borges's story "Tlon, Uqbar, Orbis Tertius" which can be found in Collected Fictions. It focuses on the ways in which the assumption of philosophical idealism, reflected in the very languages of the world of Tlön, affect not just the mindsets of the people, but even the disciplines studied and applied within it. The most important discipline is psychology, with all other disciplines being subordinate to it. Metaphysics is evaluated on aesthetics grounds and is viewed as a portion of fantasy literature. To support my ongoing work, go to my Patreon site - www.patreon.com/sadler If you'd like to make a direct contribution, you can do so here - www.paypal.me/ReasonIO - or at BuyMeACoffee - www.buymeacoffee.com/A4quYdWoM You can find over 3000 philosophy videos in my main YouTube channel - www.youtube.com/user/gbisadler Get Borges' Collected Fictions here - https://amzn.to/3xZnwHA