In today's Washington Post, Anne Applebaum wonders over the seeming disparity between American society's trust in financial transactions that are often paperless and our distrust of electronic voting systems that don't produce a paper ballot:

When the ATM asks whether I want a receipt, I usually say no. When a Web site wants my credit card number, I usually say yes. When I pay bills online, there is no paper record of the transaction. In my failure to demand physical evidence when money changes hands, I am not very unusual. Most Americans now conduct at least some of their financial transactions without paper, or at least sleep happily knowing that others do. Yet when it comes to voting -- a far simpler and more straightforward activity than electronic bank transfers -- we suddenly become positively 19th century in our need for a physical record.

It is, if you think about it, quite inexplicable.

She carries on for several more paragraphs, meandering among conspiracy theories, the lack of any evidence of vote fraud, irrational paranoia about computer voting, distrust of politicians, and on and on.

But, Occam's Razor being what it is, it's much simpler than that.

While we may not have a paper record of financial transactions, they're auditable. We can see when, where and how much we're charged, how much is credited to or debited from our charge accounts, how much is paid to a merchant, and so forth. We can follow the trail, even though it's electronic, every step of the way to ensure that the numbers at the beginning, although rearranged and split and recombined, match the numbers at the end.

But voting is intended to be anonymous. By design, your vote can't be traced back to you. In this day and age, that may be an anachronism; I can't imagine where I'd be concerned about who may know how I voted on any particular candidate or question on the ballot, but let's say the anonymous approach is still necessary.

With that in mind, once you cast your vote electronically, you can't audit it. You can't trace it through the system to ensure it was counted, or if it wasn't, figure out why. It's completely anonymous and not auditable.

That's why we need a paper printout of our votes to accompany electronic voting. We need the computer to tell us how it thinks you voted, so you can examine it for accuracy and confirm your vote by depositing your paper record so that it can be used should any recount (it's just an audit, after all) be conducted. In a purely electronic system, what's to recount? All you can examine are aggregate counts, by state, county or city, district, precinct or machine, but no matter how finely you slice it, since it's anonymous, your vote will never be examined except as a part of some group of votes.

That's why it's vital now and for the foreseeable future to require electronic voting systems to produce a paper trail. Our votes must be auditable.