Suddenly, everything is a computer. Phones, of course, and televisions. Also toasters and door locks, baby monitors and juicers, doorbells and gas grills. Even faucets. Even garden hoses. Even fidget spinners. Supposedly “smart” gadgets are everywhere, spreading the gospel of computation to everyday objects.

It’s enough to make the mundane seem new—for a time anyway. But quickly, doubts arise. Nobody really needs smartphone-operated bike locks or propane tanks. And they certainly don’t need gadgets that are less trustworthy than the “dumb” ones they replace, a sin many smart devices commit. But people do seem to want them—and in increasing numbers. There are now billions of connected devices, representing a market that might reach $250 billion in value by 2020.

Why? One answer is that consumers buy what is on offer, and manufacturers are eager to turn their dumb devices smart. Doing so allows them more revenue, more control, and more opportunity for planned obsolescence. It also creates a secondary market for data collected by means of these devices. Roomba, for example, hopes to deduce floor plans from the movement of its robotic home vacuums so that it can sell them as business intelligence.