In achieving the unlikely feat of making her arse look unattractive, Cheryl Cole has drawn our attention to one of the most significant cultural changes of recent years - namely, the change in attitudes to self and identity as betokened by the boom in the number of people with tattoos.

In my formative years, pretty much the only people who had tattoos were sailors, convicts and bikers. This was because, to us, nothing mattered so much that we wanted a permanent mark of it on our bodies. The breakdown of traditional class, gender and religious sterotypes in the 60s, 70s and 80s led to a fragmentation and weakening of senses of identity. And insofar as identities did still exist, they were things to be escaped from, as tools of class, gender or racial oppression; it's no accident that slaves and concentration camp victims were branded and tattooed.

This was reflected in pop culture. The most iconic pop stars of the 70s and 80s were David Bowie and Madonna, who adopted and discarded identities and personas. And the most significant pop lyric was "This means nothing to me."

We were - whether we knew it or not - postmodernists, Rortyean ironists who kept a distance between our "selves" and our beliefs and our identities.

What we're seeing with the rise of tattoos is a backlash against this, a desire to close this gap - to identify the self/body with what one believes or loves. Whereas my generation had the artifice and alienation of Bowie and the new romantics, today's tattooed generation has "urban" music and pseudo-folk singer-songwriters with prentensions of being "real" and "authentic." "Humankind cannot bear very much reality" wrote T.S.Eliot. But nor can it bear very much scepticism and alienation. The atomic individual of liberal and conventional economic imagination - Amartya Sen's "rational fool" - is not something people aspire to be.

Does this matter? Perhaps, for two reasons.

One is that it is potentially illberal. The more people identify with their beliefs, the more they are likely to regard challenges to them as not just a clash of ideas, but as affronts to their selves. The rise of tattoos and the increase in the numbers of people "taking offence" are in this sense two aspects of the same phenomenon.

Secondly, as Akerlof and Kranton have shown, identities influence our economic behaviour. Our perceptions of who we are, and of whom we wish to identify with, shape not only our consumption decisions but also our career choices. There is, therefore a danger that identities might constrain our options and limit social mobility, by trapping people into gender, class and ethnic roles.