1. Misleading Feedback
Most people are capable of learning difficult skills like swimming, riding a bike, or cooking a decent meal because these activities provide a lot of instant feedback on what you’re doing right, or wrong. If you put far too much salt in the sauce, your pasta will taste memorably bad. The next time, you’ll know what mistakes to avoid.
But some activities, including dangerous ones, provide negative feedback only rarely. When I am in a rush, I often cross the street at a red light. I understand intellectually that this is stupid, but I’ve never once seen evidence of my stupidity. In fact, every time I cross on red, the world sends me a signal that it’s safe: After all, I’ve never (yet) been hit by a car! So I keep crossing on red.
Exposure to COVID-19 works the same way. Every time you engage in a risky activity—like meeting up with your friends indoors—the world is likely to send you a signal that you made the right choice. I saw my pal and didn’t get sick. Clearly, I shouldn’t have worried so much about socializing! But that is just as wrong as thinking that jaywalking is safe because you haven’t yet been hit by a car.
Read: Just because you can doesn’t mean you should
Let’s assume, for example, that going to a large indoor gathering gives you a one in 20 chance of contracting COVID-19—a significant risk. Most likely, you’ll get away with it the first time. You’ll then infer that taking part in such gatherings is pretty safe, and will do so again. Eventually, you are highly likely to fall sick.
2. Individually Rational, Collectively Disastrous
We tend to think behavior that is justifiable on the individual level is also justifiable on the collective level, and vice versa. If eating the occasional sugary treat is fine for me it’s fine for all of us. And if smoking indoors is bad for me, it’s bad for all of us.
The dynamics of contagion in a pandemic do not work like that. If the case numbers in your part of the country are still relatively low—spoiler alert: They’re not—inviting five of your friends over for an indoor dinner party might not pose an unacceptably high risk for any one of you. As long as everyone is relatively young and nobody has serious preexisting conditions, the direct risk to your health is quite small.
But if everyone who isn’t at especially high risk held similar dinner parties, some percentage of these events would lead to additional infections. And because each newly infected person might spread the virus to others, everyone’s decision to hold a one-off dinner party would quickly lead to a significant spike in transmissions.
Read: The pandemic safety rule that really matters
The dynamic here is reminiscent of classic collective-action problems. If you go to one dinner, you’ll likely be fine. But if everyone goes to one dinner, the virus will spread with such speed that your own chances of contracting COVID-19 will also rise precipitously.