Demarcation
Explanation
The Joke
The comic addresses the "demarcation problem" -- the philosophical question of how to distinguish between hard science and soft science. A character suggests a simple test: put the word "mad" in front of a practitioner of a discipline and see how scared you are. A "mad chemist" is scary because they are a "mad genius death-ray killer robot-making killer," which makes chemistry "very scary, hard science." A "mad conservation biologist," on the other hand, might be scary but in a different way -- maybe they are "bringing back the thylacine for social justice reasons or something."
The comic continues with a "mad anthropologist," who might be "studying certain cultural beliefs" in an unsettling way. The character then claims you can easily separate the "hard" and "soft" sciences this way, noting that a "mad meteorologist" would just be someone who "talks crazy about the weather" -- not actually dangerous. In the final panel, another character says "I can't tell if this is true or just stupid," to which the first character responds: "That's because I'm a mad epistemologist!" -- an epistemologist being someone who studies the nature of knowledge and truth itself.
The Humor
The humor comes from the absurd but oddly intuitive metric being proposed. There is a genuine correlation between how dangerous a "mad" version of a scientist could be and how "hard" their science is -- a mad physicist with nuclear weapons is terrifying, while a mad sociologist is mostly just annoying at dinner parties. The final punchline is self-referential: the inability to tell whether the argument is true or stupid is itself an epistemological problem, and the character claiming to be a "mad epistemologist" means they have weaponized the very tools we would use to evaluate their argument.
References
The demarcation problem is a long-standing question in the philosophy of science, famously addressed by Karl Popper (who proposed falsifiability as the criterion) and later by Thomas Kuhn and Larry Laudan. The thylacine (Tasmanian tiger) is a marsupial that went extinct in 1936, and de-extinction efforts have been a topic of scientific discussion. Epistemology is the branch of philosophy concerned with the nature, sources, and limits of knowledge.