Double-Edged
Explanation
The Joke
A researcher at a podium announces that after a decade of research into the history of science, they have concluded that "all technology is double-edged." Someone from the audience asks: "What about single-edged swords?" The next panel shows a newspaper headline: "Prominent Historian Commits Seppuku" — a form of ritual suicide performed with a single-edged blade (a Japanese katana or tantou).
The Humor
The comic operates on multiple levels of wordplay. The researcher's thesis — that all technology is "double-edged," meaning it has both positive and negative consequences — is a common and fairly uncontroversial observation in the history of science and technology. But the audience member's question takes the metaphor literally: what about swords that are literally single-edged?
The punchline escalates the literalism to dark absurdity. The historian, presumably unable to cope with having their grand thesis undermined by a pedantic counterexample, commits seppuku — which is performed with a single-edged blade, thereby proving the point that at least one technology (the single-edged sword) has a clear single purpose (cutting). The joke also works because seppuku itself is a "double-edged" act metaphorically — it's both an act of shame and an act of honor in Japanese tradition, ironically reinforcing the historian's original thesis even as the method of death seems to disprove it.