Since 2012, IBM has been conducting a research project to develop an artificial intelligence that can engage in a real-time formal debate with humans. The first public demonstration featured a debate between a machine and Noa Ovadia, the 2016 Israeli national debate champion on the assertion "We should subsidize space exploration." The topic was chosen from among a set of possibilities designed to ensure meaningful debate, but the AI was not specifically trained on the subject. Each side gave a four minute opening statement, a four minute rebuttal and a two minute conclusion. A poll showed that a majority of the audience thought the AI enriched their knowledge more than the human debater. AFAIK, no "winner" was chosen.
As a former debater, I am aware that winning a debate is not the same as arriving at truth--sometimes it's quite the opposite. Still, to debate effectively requires more than simply having a large set of facts to choose from; it requires an understanding of the logic of argument and the ability to persuade. This goes way beyond the abilities of Siri or Alexa. For now.
I haven't been able to locate a complete video of the debate, though I imagine one will be available soon. In the meantime, IBM has posted a teaser here, and you can find details in their project blog. Like most of the developments in AI one can see both good and bad possibiliites: imagine conversing with an AI as a means to clarify your thinking about a topic. Now imagine an AI robocaller with superior persuasive abilities. Fascinating stuff, I think