Facebook has two big problems. Solving one might make the other worse.

It's almost a cliché in Silicon Valley now. "The pivot" — turning a company around to focus on a new goal or message — is something every young firm seems to go through. But when the company in question is Facebook, a pivot is no joke. With what is possibly history's largest customer base, changes at Facebook affect people across the globe.

So it seems worth poking at what happened this week, when Facebook presented a new vision for itself as a company focused on privacy.

The new, shiny image...