Collecting postal history has gone from a labor of seeking out interesting shops and sales and digging through musty boxes to one of logging on to eBay, typing in a search request (19th-century postal history), and clicking on whatever envelope covers catch my eye. The search process has for all practical purposes become frictionless, and the net result is that it just isn't fun anymore. My collection has been placed in a storage locker. I'm done with it.

Now I realize that the economic language of frictionless markets isn't very romantic, but the fact is that the dating game is a kind of market whether we want to admit it or not. Finding a partner used to be expensive, and the market was inefficient. If you lived in a large city, there were always people looking for partners, but the problem was how to find them. Pick-up bars were imperfect markets to say the very least. Now you go online, select a partner, and you are immediately dating someone who is at least interested in you. Of course online dating is still work, but the emotional labor and risk of failure has been significantly reduced.

Slater picks up on two unintended consequences of a low-friction dating market. First, if it is too easy to find something you just don't value it as much. If diamonds grew on dandelions no one would care about diamonds. The other consequence is that it reduces the cost of moving on to something new. Not only is what you have less valuable, but trading for something new is less expensive as well. Sure, there is the breakup drama, but online dating markets mean you won't have to suffer that drama sitting home watching sad movies; you can find a replacement within days.

I agree that those are two of the problems with online dating markets, but they are really just the tip of the iceberg. Here is another problem that I consider to be more serious. One advantage of inefficient dating markets is that in times of scarcity we sometimes take chances on things we wouldn't otherwise try. In times of plenty, we take the path of least resistence (someone who appears compatible) and we forgo difficult and prima facie implausible pairings. And this is our loss. 1950s romantic comedies turned unlikely pairings into a formula—happenstance throws two unlikely people togetherand the sparks and romance begin. We all understand this kind of romance—it involves the strange chemistry of putting together two people who are, on the face of it, incompatible. Of course online dating services can randomize their matching algorithms to supply unlikely options—but these options are always served against a backdrop in which more likely options are plentiful, easy to obtain, and on the face of it less risky. We need the scarcity to propel us to try the unlikely pairings.

Much of what is valuable in this world is the product of mashing up ideas or music or personalities that are on the face of it incompatible. And the secret is that great chemistry (for example in music) isn't about putting together people who are on the same page—it is about putting together people who are different and making it work. The result is often unexpected and beautiful. So it is with relationships; compatibility is a terrible idea in selecting a partner. It leads to stasis, both for individuals and for relationships and (turning my music example into a metaphor) it leads to music that is predictable and unexciting.