I understand exactly what you are saying, but you are looking at things in a different way than human (business) behavior actually operates. Yes, if all businesses were to simulatiniously increase their production, they would hire people, and those people would spend (more) money, and thus the simultanious but unilateraleral production increase may be economically justified. Most of conservative economic theory is 100% correct - from a macroeconomic theoretical point of view.
But in reality, no business is going to just randomly crank up production without the realistic expectation of an increase in orders (sales). From the standpoint of the individual business (micro-economics), that doesn't make any sense. I, as a business owner/manager have absolutely no reason to believe that just because I independantly increase my production, that my sales are going to increase. The only way that I would make such an assumption is if sales were trending upward over a long period of time with no chance of a decline seeable on the horizon. But of course there is ALWAYS a very likely chance that sales will either decline or quit increasing, so any business manager who expands faster than actual real life current conditions warrent, with the expectation that every other businesses is also going to expand, would be a fool.
Besides, many businesses, like mine, cannot produce until there is an order. Everything I make is custom. I make custom signs, custom commercial printing, custom screen printing, custom advertising specialty items. I can not produce a custom product without an order for a custom product. Think about it. You think I would just randomly make some signs hoping that a business with that particular name and address and phone number in that particular industry with that particular logo and corporate colors would just happen to place an order for the sign? I'd be much better off "investing" in the lottery than investing in speculative production.
While conservatives have cornered the market in unproven (and unprovable) macro economic theory, they don't have a clue about individual business and consumer microeconomic behavior. The practical application of macroeconomic theory depends on the aggregate of microeconomic reality.