The idea of a unified reputation currency is starting to take hold online, writes Josh Klein in the blog of the Harvard Business Review.

“With broad agreement that reputation is a form of value, and various mechanisms already existing to score people and institutions on it, convergence on one metric seems achievable—even inevitable.

It’s an enormously appealing idea. Imagine you could type in my name or email address or social software account and get a single number by which to judge whether you should do business with me—or indeed whether you should bother reading my point of view. What if, as a business, you could get a single number to determine how much to discount your product for a particular customer (because they might promote the product if they like it) or better yet, increase the price for those unlikely to enhance its appeal to others? Regardless of your motivation, having a single number to replace what would be a messy evaluation would be a huge convenience that computers seem ideally suited to provide.

But the idea is fatally flawed. As someone who is subject to hysterical bouts of techno-utopianism myself, I can recognize the signs. We want a single number to evaluate other people by, and it really, really, really seems possible, so it must be so. Except that it isn’t.

It’s nearly impossible firstly because reputation is so deeply context-dependent.”

[My emphasis]