The Group of Seven, comprised of leading democratic industrial nations, has long looked past its prime. Once accounting for about 70 percent of the global economy, its members now constitute less than 50 percent. It has been eclipsed by the Group of 20 as the top institution for global economic guidance. Still, an intimate gathering of leaders of those countries could be valuable if they forged a common front on issues of concern. Yet even that is proving too big a challenge in the era of U.S. President Donald Trump, whose "America First" agenda and mercurial temperament have proven virtually insurmountable obstacles to joint action.

The Trump factor was evident before this year's meeting began, when the host, French President Emmanuel Macron, announced that he would issue no joint statement after the summit for the first time in the group's 44-year history because "it's pointless." He knew that Trump would not agree on the issues that it would address, such as fighting global warming and protectionism. Macron was also recalling the dispute that followed last year's meeting in Canada, when Trump took offense at comments by Canadian Prime Minister Justin Trudeau, said he would withdraw his signature from the joint statement and then verbally attacked Trudeau.

The intimacy of the G7 is also a problem. If discussions among heads of state are to be meaningful and productive then participants must be able to trust each other. There are no position papers or documents that provide a baseline for analysis and consensus. Trump's fabrications, exaggerations and meanders undermine the value of those conversations by depriving them of a factual basis. It's impossible to develop a foundation for meaningful action if participants' statements aren't credible.