Disease, sickness, illness, disorder, condition . . .

First of all, I should acknowledge that Kathy A. is basically right, I was a bit sloppy with my vocabulary. ASPD is a pretty vague and often circular diagnosis that can be applied to anybody who badly misbehaves; what I really meant to defend is the much more specific, and rare, label of psychopathy. What I meant to say is that the diagnostic label should be reserved for people who truly lack the capacity for empathy.

So let's back up a bit. In medicine, diseases are usually defined in terms of an etiological process. Similar symptoms may be ascribed to completely different diseases, e.g. infection by different viruses; while people with no subjective symptoms may be given a diagnosis because of some biological fact which is believed to create a risk for illness (the subjective experience of poor health) in the future, e.g. HIV infection or hypercholesterolemia. Physicians generally don't like to call clusters of symptoms without a known etiology diseases, rather they call them syndromes, and they tend to argue about the ontological status of such entities. Good examples are fibromyalgia and chronic fatigue syndrome.

In psychiatry, however, etiology is generally unknown. Practitioners like to tell stories about causation but they are usually poorly supported by evidence. Drug companies also market theories about biological causes of DSM-defined diseases but these are largely mendacious. For example, they have convinced most people that a disease called depression is caused by a deficiency of the neurotransmitter serotonin, but this is almost certainly false. The evidence for this is supposedly that drugs which increase serotonin levels alleviate depression, but even if that were true -- which it is not for the large majority of people diagnosed with depression -- it would not demonstrate that depression is caused by serotonin deficiency. Amphetamines cause people not to feel hungry even when they don't eat, but that doesn't mean that the cause of hunger is amphetamine deficiency, even less that the solution to hunger is amphetamines.

The DSM entities are defined by symptoms, mostly consisting of descriptions of behaviors, not by etiology. Since human behavior is continuously variable, highly flexible, highly complex, and mutable, it's very hard to rigorously sort people into behavioral buckets. Generally speaking, only the most stereotypical, rigid and simple kinds of behaviors can be measured unambiguously. For example, Tourette's Syndrome has a strong ontological claim, because we can say quite definitely whether or not a person has an uncontrollable, repetitive behavior of injecting inappropriate words into conversation. But those sorts of entities are usually thought of as neurological rather than psychiatric, and once a definite etiology is discovered, they cease to be the province of psychiatry at all.

So, now I hope I've cleared the decks enough to discuss BPD. My basic reason for wanting to do so is to argue that it is not entirely feckless to look for psychodynamic explanations for emotional and behavioral problems, and that perhaps there is a coherent story to be told about "normal" human personality development and the ways in which the social environment can derail it. We need a definition of "normal" in order to say that, and in fact the word has multiple meanings. But it can mean more than just whatever the culture currently happens to find morally meritorious, or whatever happens to be most common. In both those respects, homosexuality used to be abnormal, as it still is for some people, and probably always will be in the latter respect. But I mean to argue that BPD is different.