The stimulus will work because enough economists are saying it will work that their prestigious postnominal credentials will impress enough of the masses into thinking it will work, which in turn will make it work.
And for those who enjoy the engineering details of levitation devices, here' Frank's technical description of his Rube Goldberg self-bootstrapping perpetual motion machine:
The argument of stimulus opponents hinges on their belief that consumers and businesses will predict that stimulus won't work. The fact that stimulus opponents are far less numerous, have less distinguished academic credentials, on average, and are far less ideologically diverse than their counterparts does not guarantee they're wrong. But these factors should make rational consumers and investors less likely to side with them. And since this is really an argument about expectations, that's probably enough [to win the argument claiming that stimulus spending will reduce the government's long-run debt burden by shortening the downturn, and thus stimulus spending will not making matters worse.]