Does it make sense to say you can diagnose a syndrome? (I am asking in the context of Asperger Syndrome but the question is a general one.) This is something I was trying to figure out recently. I hope people here can help me to get clarification on the issue.

Here’s where I have got to so far.

To give a diagnosis means to say what the thing is which is causing the symptoms. So suppose that I have got a sore throat and fever and a runny nose. And I get a diagnosis saying that I have influenza. Then this diagnosis is saying that there is some organic infection which is causing the symptoms. And this diagnosis explains the symptoms. In general in a diagnosis we can say: “your symptoms are caused by the fact that you have (this other thing) X which is what we have diagnosed you as having”.

On the other hand, a syndrome is just the name of a collection of symptoms. So by saying someone has some syndrome you are just saying they have those symptoms. You are not saying anything about the cause of those symptoms. So saying someone has a syndrome isn’t a diagnosis and it doesn’t explain anything.

If you tried to claim that you were explaining something by saying someone has a syndrome, then you would want to say something like “your symptoms are caused by you having S syndrome”. But S syndrome means nothing more than that you have those symptoms. So then this means you are saying: “your symptoms are caused by the fact that you have these symptoms”. It’s like saying: “that pain in your head is caused by the fact that you have a headache”. (It might even be: “your headache is caused by the fact that you have a pain in your head”.)

I read about Asperger Syndrome that when people get diagnosed with it, then this explains to them their symptoms. But I don’t see that it does do that. It just says they’ve got whatever symptoms they have. But they knew that already. Or does it tell them that they have some symptoms that, up until then, they had not noticed? But then that’s something different again from diagnosis.

Despite all of the above, I can see how saying someone has a syndrome is saying something substantive even though we are not saying what the cause is. Is this because, having noticed that certain symptoms clump together, the presumption is that there is a cause but we just don’t know what it is yet? For example Down Syndrome. But then that shouldn’t be called a syndrome anymore. Because now we do know what the cause of Down syndrome is.