I got this little gem of a comparison from someone else, I forget who, but don't credit me for it. Anyway... There are a lot of people who think that if we raise taxes on gasoline, then people will drive less or buy more fuel efficient cars. Sounds like a reasonable theory. Here's the problem. Most of the people that hold to that idea are liberal or left-wing or Democrat. And those are the same people that want to raise taxes on income and businesses. Yet while they think taxing gas will lower the amount of gas people buy, they don't think that taxing work will lower the amount of work that gets done.

It will. If I have to give 50% of my income to government, I don't have as much monetary incentive to work hard as I would if they only took 30%. But you know what? Personal income doesn't go far enough to explain this. Let's look at a business.

I am company X, and I have a great idea for a product. I estimate $100 for startup costs, a 90% chance the project utterly fails and I lose that $100, and a 10% chance that it succeeds and I earn $1000. So the business weights the outcomes, (0.9)(-100)+(0.1)(1000)=$10. So I do the project because I have a positive expectation. Sure, there's a lot of risk, but the risk is worth the possible payout. But then the government raises taxes. All of the sudden the best I could expect to make with that 10% success rate is $800. Now the equation reads
(0.9)(-100)+(0.1)(800)=-$10. No longer do I want to do the project.

Raising taxes cannot help but to lower the amount of risk companies are willing to accept when innovating, which means innovation slows down big time. But people who complain about rich companies needing to pay more (they already pay ridiculous rates) don't understand this concept. This effect ripples across the economy in all sorts of businesses, and will slow down growth, productivity, and innovation.