There is one economic truth that both political parties will agree on (it is long past time to change the rule against ending a sentence with a preposition). When talking about poverty, Republicans and Democrats will say that a rising tide lifts all boats. I would qualify that by adding that a rising tide lifts all sea-worthy boats. Since a rising tide serves as a metaphor for a growing economy, the principle of displacement applies.
We have known about the principle of displacement since Archimedes yelled, "Eureka" in his bathtub over two thousand years ago. However, the relevance of that principle went largely unnoticed in ship building until the last century and a half. Prior to that time, ships were built with materials of inherent buoyancy (Wood, witches, ducks, etc.). Nowadays we build ships of steel weighing hundreds of thousands of tons.
So, let's spell out the metaphor. The economy is the sea level, your personal wealth is the size of your boat (of for Mitt Romney, yacht), and your taxes are the payload on the boat (ship). In order to bettor understand the power of displacement, I invite the reader to fill a glass with water, up to the top. Now place something in the glass, even an ice cube, but have a paper towel handy. The glass will overflow. Likewise, if we overburden vessels with taxes, they will founder and sink under the water. The sinking of that vessel could raise the level of water so quickly as to overwhelm other boats. This would be bad.
Beginning 30 years ago, we took a different course. We made a decision to decrease the payload of the largest ships. Though they were in no danger of foundering, we lessened their tax burden. The irony here is that by lessening their tax burden (aka payload), these ships displaced less water and rode higher. As a result of their riding higher, the water level decreased. Hence, any rise in the tide that would lift all boats was offset by the lower displacement of the lightened payload.
So, hear we are, 30 years later. The Republicans who've pushed this agenda tell us we are drowning in debt. Debt caused mostly by reducing the tax burden of those large, not in danger of foundering ships. Thousands of houses are underwater (they don't float). These houses were not driven underwater by reckless borrowing, as the right would have you believe. The primary cause of the housing bubble was demand for securitized mortgages by the Masters of the Universe.
To recap, millions of people are drowning in their houses under shallower water than ever. The only boats that have risen are the largest ones. Any suggestion to increase the payloads, and therefore the displacement of these boats is met with charges that this will destroy an economy that functioned when these boats carried a maximum payload that more than doubled what it does today.
What am I missing?