The strategy he used is called running a kritik. Depending on what style of debate you’re doing and what league you’re in, kritiks can operate in a host of ways. The basic gist, though, is this: A kritik is an a priori argument, which means it has to be addressed before either side of the debate can move on to talk about anything else. The term “kritik” didn’t come into the common debate lexicon until the 90’s—long after Cruz’s days as a parliamentary debate champion were over. But the strategy existed and was fairly common during his time in academic debate.

Anyway, a debater who runs a kritik (or that style of argument) argues that the entire premise of the debate round is fundamentally flawed. For example, in 2013, two African-American college students—Ryan Walsh and Elijah Smith—won the Cross Examination Debate Association’s national championship in part by deliberately ignoring the tournament’s stated resolution and, according to The Atlantic, arguing instead that “the framework of collegiate debate has historically privileged straight, white, middle-class students.”…

“One of the things Cruz seems to have learned from his debating experience is that it’s powerful to identify shared assumptions with the audience and then use those shared assumptions to your advantage,” said Kate Shuster, co-director of the Middle School Public Debate Program who once coached a team to the championship of the National Parliamentary Debate Association.