A friend who works in social care speaks to me earnestly about a troubled young colleague: ‘Of course, she’s got a borderline personality disorder…’ I check her there: ‘What do you mean by that?’ She thinks for a moment and continues: ‘Well, she’s very emotional, she can’t maintain relationships, and she’s very defiant…’ I wait for a moment to see if there’s anything else before I say my bit: ‘Perhaps she just has a bad character — because fundamentally that’s all a personality disorder is: epithetic psychiatry.