Perhaps the first step toward solving the free rider problem is to accept that each of us is a free rider in some area. I may drive a dirtier car or have more kids or shop at stores that horribly exploit their workers, but maybe those things are offset by some others that improve the commons of whatever in some other way, like composting, walking on short trips, and volunteering to build homes for the poor.
But the free rider problem is both a real concern and also an overused excuse with regard to the commons. On the one hand, it can be difficult to get enough participation to make a commons viable, and then it can be too easily destroyed by the thoughtless or even intentional abuses of a few.
Sometimes I wonder if the only defense against free riding is thoughtful , moral awareness so that we recognize the incentives to free ride before we are lured by them. And yet can it still be avoided?
In a work situation, on a team, let's say, there are stronger and weaker members, or some whose strengths are more valuable at one time than those of others. Consequently, some of us may be free riding on the talents or work ethic of others. But in a small team, especially if it is well formed, in the end everything could balance out, so that everyone feels fairly compensated and also not exploited.
So here's the first part of the taxonomy of free riding: knowing and unknowing. Some are clearly aware that they are skating on the labors of others and not contributing fairly in spite of their ability. Others may honestly feel that they are contributing mightily, but are misdirected in what they're doing to improve the whole.
Now a second part: caring and uncaring. Some, like ranchers who gleefully avoid payment for use of federal land, are the uncaring. Then there are those who are keenly aware of their free riding and are concerned enough to seek ways to mitigate it. It sounds insane, I suppose, but some are happy to pay their taxes for just this reason.