DAVOS, SWITZERLAND — In her 2017 track “Power”, pop superstar Katy Perry warned to not “mistake my warmth for weakness.” On Tuesday, she watched her beau Justin Trudeau argue that it’s a mistake to underestimate soft power amid instability not seen in 80 years. On Tuesday, the former prime minister gave a keynote address at Brand Finance’s Global Soft Power Summit on the margins of the annual meeting of the World Economic Forum. As Perry watched impassively from the front row, Trudeau told the crowd of roughly 100 attendees and journalists that democracy is “backsliding” everywhere...