Yeah that's why I called it philosophical, because the idea is a little more involved, shall we say. I'm not a god of this, so speculation ahead bewarned. In cases that aren't clear cut, you would also need contextual data like bigger actual physical area, or over time dimension, really any data point that can help narrow down what the thing is. It wouldn't just be pure deep learning stuff, it would be some kind of memory and data store of already classified objects and contexts. In the ultimate end, ALL of it would be sparse, but classify perfectly just that one thing it is built to classify. And if that doesn't work, several sparse things combined would result in one unique thing. On the sparsity matrix wikipedia page there is an example of balls with a string through them, this would correspond to the data being the balls and the systems we build (or alternatively unsupervised learning methods for finding new strings), whatever they may be, would be the strings (assuming all the strings are actual informational and correct to natural world). But you need the balls to begin with etc. Since all of this information should be in the natural world by its own, and also accessible to us