disjunction
Explanation
This comic is about formal logic, specifically the concept of a "vacuously true disjunction." A man is defending himself to his partner (or friend), insisting: "No, I was NOT wrong when I said we didn't need to book tickets early. At the end of my statement, I appended a vacuously true disjunction!"
The other person demands: "Stop appending vacuously true disjunctions to your statements!" The man responds: "I promise I will" with small text that likely reads "or I won't" -- itself another vacuously true disjunction.
In formal logic, a disjunction is an "or" statement (P or Q). A disjunction is vacuously true when at least one of its disjuncts is a tautology, or more colloquially, when you add "or not" to any statement, making it trivially true regardless of the original claim. For example: "We don't need to book tickets early... or we do" is technically always true because it covers all possibilities, but it's completely useless as practical advice.
The joke satirizes the gap between logical validity and practical usefulness. The man is technically correct that his statement was "not wrong" -- a disjunction like "P or not P" is always true -- but it was also completely meaningless as advice. The final panel delivers a second punchline: when he promises to stop, he appends yet another vacuously true disjunction ("or I won't"), making his promise itself meaningless. This is a classic SMBC logic joke, finding humor in the ways formal logical principles can be weaponized in everyday arguments to be technically correct while being practically useless.