You’re upper-class if a collapse in the economy as a whole is the only thing that could threaten your standard of living.

You’re middle-class if a fall in the market value of work in your profession would harm your standard of living. (Think of all the computer programmers worried that cheap competition from India is going to make them unemployable.)

You’re lower-class if, along with the above two risks, you face the risk of losing your physical capacity to perform the labor. (Think of a factory worker whose hands get mangled in an industrial accident.)

I think that there is an interesting analysis of class based on exposure to risk, which creates room for that bastard entity the “middle class”, which famously doesn’t have any room to exist in class theories (like Marx’s) based on relationship to the means of production. Say we define three classes thus:

• The “upper” or rentier class, whose standard of living is at risk if the economy as a whole fails to produce as much as anticipated.
• The “middle” class, whose standard of living bears the risk of surprises in the production of firm-level business units (economic entities larger than a household but small relative to the economy as a whole).
• The “working” class, who bear both of the above risks, but who are also exposed to risks associated with their own bodies.

It’s not a fully worked out theory, so don’t take it seriously. But it strikes me that what’s bad about being a proleterian in Marx’s analysis is that you have to sell your labour in order to live, and a lot of what’s bad about [it is] that the fluctuations in your ability to supply it are potentially as dangerous to you as fluctuations in the demand for it. I’d certainly argue that one of the biggest differences between the working class and the middle class in the ordinary language senses of the terms, is that if you’re middle class, it’s not such a big deal to miss a few days through illness.

Lots of other interesting stuff in that posting … check it out.