Thomas Walkom rightly notes that this fall's election has seen somewhat more discussion of government acting in the public interest than we've seen in some time. But it's worth drawing a distinction between the varieties of intervention on offer from the NDP and the Libs respectively.
As much as the latter have tried to suggest that running immediate deficits is the sole measure of progressivism, the real difference between the two lies in their longer-term plans.
For the NDP, the goal of an active government is to build up a stronger social safety net over time. Immediate funding for child care, pharmacare and other programs is intended to set the stage for the development of stable and sustainable structures which can withstand even the most harmful of governments - just as the health care system set up decades ago is still broadly in place despite the cuts and neglect inflicted by the Libs and Cons since the 1990s. (Of course, we should also see the value in putting our existing programs on a stronger footing.)
It's true that this focus on the longer term means that not everybody in need of child care immediately will get it: the goal isn't to shovel money out the door, but to develop a program that works. But in a context where no party is offering immediate implementation of universal child care, it raises the possibility - ruled out by the Libs - that a fully-implemented program will eliminate the same dilemma for all Canadian parents for decades to come.
In contrast, the Libs' pitch is for a government which leaps into action immediately, then flees from the picture equally quickly a few years down the road. (And I'll leave aside for now the issues with trying to turn short-term infrastructure into long-term P3 contracts.)
In effect, the NDP is proposing an improved nutritional regimen for the public sector to bolster its long-term health, while the Libs' plan is limited to a temporary shot of adrenaline. And while we may be at point where it's best to pursue both to reverse the damage the Cons have done, the former is surely the path most worth pursuing if we want to see benefits that last past a single election cycle.