There are no emotional qualia.
As I have discussed before, it's all very well saying you're happy, but how can we possibly tell that your happy is the same as my happy? Describing it is no good, because any qualitative words we use would by definition only refer to our own emotional experiences and our personal definitions. The only way to be sure would be to become each other and then... well we'd actually be each other so we still wouldn't be able to compare and contrast.
Given that this is the case, it is odd that some emotions are treated the same in different people. Treated being the operative word. I am talking about depression.
Unfortunately it's an emotion that is never really taken seriously and often misunderstood. On the one hand the unsympathetic tell you to "snap out of it", "pull yourself together" or "cheer up (it may never happen)" whilst on the other the condition is used to describe trivia: "I'm so depressed - Tesco's have sold out of muffins". On the third hand some people consider it a stigma, get scared and run away as if they're afraid it might be contagious.
There's a fourth hand as well, but I'll get to that later.
It's an odd state of mind which is difficult to work out the reason for. Is it a malfunction arising as the result of something else, or a remnant of an archaic (preconscious?) mindstate like some kind of psychological appendix? Or, just like physical pain, is it a valid and useful way to feel even if it is unpleasant? In the absence of true qualia, the description of emotions may well be ultimately useless, but in the short term it might be able to give us a clue about the nature of depression.
As is so often the case I have to offer a disclaimer at this point. I'm no psychologist or neurobiologist. All I am doing is making observations and trying various logical explanations on for size.
For a start, depression is not the same thing as sadness or feeling upset. When my cat died recently I was sad and felt upset, but that was a short term thing and felt to be occurring in an entirely different emotional space. It was sad and bad but because there was an obvious cause and effect it felt healthier, and was over quicker. To use a physical analogy, it was the equivalent of the sharp pain and automatic reaction that occurs if you accidentally brush your hand against the ring on an electric cooker.
Depression is different. For a start there's often no obvious cause. Whilst conditions, situations and surroundings can trigger it off, you are not "depressed because..." You are just depressed. Sometimes you don't even realise that it's what you're suffering from. Occasionally it's a listlessness and lack of motivation that can be mistaken for laziness, which has the unfortunate side effect of provoking negative feedback as you start to feel worse about yourself. But most commonly it seems to manifest as a general miasma of slight despair. A sourceless low-grade dread of nothing in particular, like an unrefined fear. A cloud of unfocussed foreboding that seems to collect around the back of the eyeballs and in the sinuses, sometimes spreading downwards into the back of the throat.
You're afraid of life.
Sometimes this essence of unease is accompanied by violent self-destructive thoughts. Activities that you would once have drawn pleasure from now seem boring and pointless, but the thought of trying something new is out of the question. It would be too much effort. This is where the fourth hand comes in.
The fourth hand is that of the medical professional and it often contains a bottle of pills. This is in general a good thing because the condition is being treated like any other medical affliction with no stigma attached or implication that you're malingering or making a big fuss about nothing. However, since the Rise of the SSRIs - cheap effective and largely non-addictive anti-depressants - there has been a tendency of some GPs to use them as a universal panacea to silence those experiencing everyday mood-fluctuations which would otherwise soon pass.
However the way these drugs work does provide a valuable insight into what depression actually is.
It all comes down to the neurotransmitter serotonin, the body's very own happy juice. If you're depressed there's less of this stuff sloshing around in the system. SSRIs redress this balance. But what's serotonin actually for?
As far as I can see, like many things it all comes down to food and survival. In times of abundance serotonin levels become high, giving a good feeling. In times of scarcity this good feeling is remembered and is something to strive for - the carrot offered us by the human genome to ensure our survival long enough to pass on copies of itself. Interestingly though, this means that depression, or something very like it, is the natural state of sentient beings. Serotonin is simply the sugar added to the mix to give life a slightly better taste.
This kind of makes sense. Some theories state that consciousness arose as a heightened state of awareness to help prehumans survive hazardous times - if something dangerous was detected on the horizon their brains would go to battle stations and they'd awake into sentience. Fight or flight? Whatever option they ended up choosing a healthy dose of fear and aggression would help them through it.
And perhaps this is what depression is. The nebulous foreboding and the violent thoughts (that in today's civilized society end up being turned inwards upon yourself) are the descendants of our ancestors' red alert brain as they stood on the African veldt having just caught sight of a pride of lions slowly stalking the troupe.
The SSRIs may help us control these feelings in the short term, but in the long term we need to tell ourselves that the lions have gone.