It must be possible to build a great 7-inch tablet

There's no 7" iPad. There are lots of 7" Android tablets. And there are lessons to be learned from those facts.

At the moment, there's a bit of a dispute going on in the tech media over an intriguing question: Is Apple going to release a 7" iPad anytime soon?

In a story that's currently hidden behind a paywall, Taiwanese site Digitimes says that Apple is working on a mini-iPad--with a 7.85" display, to be precise--for release in 2012. It says the alleged device is a reaction to smaller, cheaper tablets such as Amazon's Kindle Fire.

But John Paczkowski of All Things D concludes that this rumor appears to be fantasy, not fact--at least if we're talking about a 2012 release date. Paczkowski quotes an analyst who notes that Steve Jobs once explained at length why 7" tablets are an inherently lousy idea.

I side with Paczkowski. Not because Jobs went on the record against 7-inchers: He often explained at length why something was a lousy idea only to eventually do it. And not because of Digitimes' spotty record for accuracy. (With equal abandon, the site reports on Apple scuttlebutt that pans out and Apple scuttlebutt that never amounts to anything.)

Apple's iPad 2 tablet/
Apple's iPad 2 tablet. Apple

No, the reason that a 7" iPad seems unlikely in the short term is because it would only have a shot at greatness if it had an interface and apps designed with a 7" display in mind. A 7" tablet isn't just a big smartphone, and it's not a tinier 9.7" tablet. Building a 7" iPad by essentially making the iPhone's pixels larger or the iPad's pixels smaller would be the wrong way to go about it.

Apple might be able to create a pleasing 7" iPad by making its iOS mobile operating system resolution-independent--reijiggering the software so that it and its apps are capable to scaling themselves to make good use of any number of available pixels. My guess is that hints that iOS is being reegineered to support additional resolutions will precede any reliable evidence that Apple plans to ship an iPad that doesn't have a 9.7" screen.

Toshiba's Thrive 7 tablet.
Toshiba's Thrive 7 tablet. Toshiba

In the Android world, 7" of course, tablets are already plentiful. I've been trying out a few lately, including Toshiba's Thrive 7 as well as Amazon's Kindle Fire and Barnes & Noble's Nook Tablet. (The Thrive runs Android 3.2 Honeycomb in a not-massively-tweaked form at 1280 by 800 resolution; the Kindle Fire and Nook use customized versions of Android at 1024 by 600.)

Steve Jobs might have disagreed, but to me, all three of these models show that 7" is a legitimate size for a tablet. They feel different than the magazine-like iPad 2--more like mass-market paperbacks. But they feel good.

Android, unlike iOS, lets developers build user interfaces that resize themselves on the fly for an array of interfaces; that capability is mandatory for this particular operating system, since it runs on so many phones and tablets with different resolutions. When you install third-party Android apps on these tablets, however, you see lots of little reminders that you can't make a superlative 7" tablet by simply manufacturing a tablet with a 7" screen.

Some applications scale nicely to support the resolutions provided by the Thrive, Fire, and Nook. Others scale, but in unsightly ways. (The HootSuite social-media client mostly works pretty well, but some of its buttons inexplicably take up the full width of the screen.) And some apps don't even try to use all of the available pixels. You don't know what you'll get until you try.

Bottom line: Android doesn't make apps run well on a 7" tablet, it just makes them run.

Judging from past history, I don't expect Google to revise Android in a way that forces developers to write apps that work great at any resolution on any screen size. The company isn't that bossy, and it isn't that interested in aesthetics.

Apple remains the most likely candidate to build the ideal 7" tablet. But before you assume that competition from the Kindle Fire and other 7-inchers will force its hand, consider this: People have been predicting that the company would release iPhones with different screen sizes for as long as there have been iPhones. Instead, it's stuck with 3.5" screens for almost half a decade now.

That little fact may matter more than an infinite number of experts confidently declaring that a 7" iPad is inevitable--no matter how much some of us would like to see Apple go for it.