Keynesian economics works - that's what got us from the 1950's through the 1970's without an exploding federal debt - our worst economics times since the Depression all came AFTER Reaganomics took effect. And if you'll think about it, what got us out of the Depression? Our huge military build-up for WWII, right? All the shipbuilding, all the factories, all that was paid for by the taxpayers...and their taxes stimulated the economy to the point that after WWII, we were the strongest economy the world had ever seen. If the conservatives were right that economic stimulus doesn't work, then our taxpayer-funded buildup to WWII SHOULD have driven us further down into the Depression instead of bringing us out of it.
Taxes can be too high...but they can be too low. The three times since WWI that our taxes were the lowest were in the 1920's, 1981, and in the early 2000's. And what happened following each of those times? Correlation isn't causation...but the pattern is interesting.