An artificial intelligence system has engaged in the first ever live public debate with human competitors.

At IBM's Watson West site in San Francisco, its Project Debater took on two human champion debaters in front of a live audience.

During the first of these debates the AI system competed with Noa Ovadia, the 2016 Israeli national debate champion, on the topic "We should subsidize space exploration".

Neither competitor had prior knowledge of the topic and they were given the same time to prepare.

They each delivered a four-minute opening statement, a four-minute rebuttal and a two-minute summary.

This required the IBM machine to argue, listen, respond and ultimately attempt to convince the audience of the merits of its argument.

So how did it do?

One example of this robot's rebuttals was its response to Ms Ovadia's argument that there were more important things to spend money on than space exploration.

It said: "It is very easy to say that there are more important things to spend money on, and I do not dispute this. No one is claiming that this is the only item on our expense list. But that is beside the point.

"As subsidising space exploration would clearly benefit society, I maintain that this is something the government should pursue."

And later, it even opted for an analogy: "Subsidising space exploration is like investing in really good tyres, it may not be fun to spend the extra money but ultimately you know that you and everyone else on the road will be better off."

The machine did make some mistakes too.

Its arguments were sometimes repetitive, for example it made the point that space exploration was good for the economy a number of times, just in slightly different ways. Occasionally its use of language was also clumsy.

During the second debate the AI system took on another Israeli debate aficionado, Dan Zafrir on the topic "We should increase the use of telemedicine."

In both debates the audience (of journalists and IBM staff) concluded that the human competitors had better delivery, but that the machine's arguments had more substance.

Project Debater has access to a library of millions of articles and for these initial demonstrations, IBM's director of research Arvind Krishna said the topics were selected from a curated list, so the AI system could effectively engage in the debate.

"Over time, and in relevant business applications, we will naturally move toward using the system for issues that haven't been screened," Mr Krishna wrote in a blog post.

IBM scientists and researchers in Ireland are part of the global team that has been working on this project and the company intends to commercialise this technology.

Acknowledging that their work was far from complete, Mr Krishna wrote that this technology "has the potential to assist with thousands of complicated human decisions.

"For example, by helping to identify financial facts that either support or oppose a financial thesis, or by presenting pro and con arguments related to public policies.

"Project Debater could be the ultimate fact-based sounding board without the bias that often comes from humans."

As for its human competitors, the BBC asked Ms Ovadia about the prospect of this machine becoming an even better debater.

"I think, eventually, when it can do what we do, but better, that'll be a great thing for the human race, for informed decision making, for informed voting, for informed everything," Ms Ovadia said.

"I believe that the best decisions are made by information and by logical reasoning. So I'm excited to see where it goes." she added.