Editor’s note: When people say it isn’t rocket science, ever wonder what it is that makes rocket science so darn hard? In our Decoder series, Whoopi Goldberg seeks out experts across a wide spectrum of fields to find out how things work, from the encryption on your iPod to the fine print on your tax bill. So next time you see a rocket, don’t be surprised if it’s one Whoopi built herself.

David Cay Johnston is a former writer for The New York Times and the Pulitzer Prize-winning author of Free Lunch.

WHOOPI: Here’s my first question. How is it possible that we are being taxed up the behind in such a way that no one realizes it? And the reason I say that is because you look at your bills – you know, your gas and electric bill, your phone bill, your cell phone bill. You get six or seven taxes that make no sense. Why is this OK? Why is this happening?

DAVID: Let me argue the case for why it’s done and then I’ll give you the other side of it.

WHOOPI: OK.

Click here to see just the numbers, crunched.

DAVID: If you only tax one thing – let’s say the only thing we taxed was your income, or the only thing we taxed was the house you live in, then people would find a way to get around that one tax. So you have to have an approach that taxes multiple things.

WHOOPI: So you’re telling me that basically the idea is people think people are going to cheat anyway, so we might as well just make sure they don’t have any money to cheat with?

DAVID: No, it doesn’t even involve cheating. It’s that people will simply organize their lives to get around a single tax. If there was only one tax it wouldn’t be hard to get around it.

WHOOPI: Really? Could you tell me how because I can’t figure it out.

DAVID: Well, let’s say that we taxed just wages — that’s what the flat tax proposal is. You wouldn’t pay tax on capital gains, interest, dividends, rents, royalties – most royalties. Some you would, some you wouldn’t. Well, if that’s the only tax we had then people who own a business, for example, would take a $1 salary and report everything as a capital gain — then they wouldn’t pay any taxes. You have to design the tax system to flow from the economic order; and what we have is a tax system that works against the economic order. I’ll come back to that in a second. Let me answer your question now. The reason we have all these other little taxes – your phone bill, your cell phone, your utility bill, the sales tax, all these other little taxes — is that they are perceived to be minor annoyances that the public will put up with. And the art of taxation is plucking the goose while not killing it and getting the maximum with the least amount of hissing from the goose.

WHOOPI: But do they realize that with everything that’s happening, that they are killing the goose?

DAVID: No. And I’m not sure you can make the case that they are. Taxes overall are 37 percent of the economy, net, in round figures. Figure a third – a little more than a third of the economy.

WHOOPI: But let’s take it on an individual basis. What is the tax for a middle-class person?

DAVID: For two-thirds of Americans – two-thirds of them – they pay more in payroll taxes, Social Security and Medicare taxes than they do in income taxes.

WHOOPI: OK. So this is every week, right?

DAVID: That’s right, and that’s a major part of the problem. In 1974 – now you and I were both working in 1974 — the maximum Social Security tax was about $327; it’s now going to be almost $6000. That’s an enormous increase. Even when you adjust for inflation, ‘74’s tax today would be about $1600, so it’s gone up about fourfold. And half of the decline in savings by Americans is attributable to the payroll tax collecting more than is needed to currently pay out benefits.