As their names implies, the Progressives were strong believers in human progress. They cited history in support of their belief that humankind was constantly improving, becoming healthier, wealthier, and more knowledgeable.
Of course, there was a lot of work still to do. During the Progressive era, the United States, though the richest country in the world, still had a number of serious social and economic problems that required attention. Child labor, extreme poverty, and lack of equality and opportunity for women were just some of the monumental challenges that the Progressives hoped to address.
But the Progressives, fortified as they were by a firm belief in human progress, believed that it was just a matter of time before all the social evils that afflicted society were swept away. To be sure, this wouldn't happen overnight; nor would it take place entirely of its own accord. Interested groups and individuals, such as the Progressive movement itself, would need to fight every inch of the way to make change happen.
But the Progressives were confident that this would happen. History was on their side, and they were the instruments of a historical process that would, they believed, inevitably lead to the general improvement of humankind.