Mine is certainly rational. There is no "chemical imbalance" in my brain, as the pill-pushers like to say, because SSRIs definitely did not work for me and actually made me worse.
Instead, my depression comes from a combination of external concerns, loneliness, and trauma. All of these are rational things to be depressed by.
By "external conerns", I mean big-picture issues that are largely out of my control such as the economy and the climate. Being 24, I have now witnessed two allegedly "once in a lifetime" financial crashes and there'll likely be another crash in a decade or so. What's the point in getting back up only to be immediately knocked back down because some banker's bubble popped? As for the climate, a similiar question applies: what's the point in trying in life if the tapwater won't be safe to drink by the time I'm 70?
Now, for loneliness, depression really is a rational response. We are social animals, we need to spend quality time with others, we need to be touched, we need to belong to a "tribe" of sorts. If these social needs are not met, we begin to break down on not only a psychological level but also a psychiological level (fun fact: loneliness can significantly increase your risk of cardiovascular issues even if you are otherwise healthy!) due to the instinctual stress response caused by loneliness. Despite the fact that we evolved this instinct in the stone age, back when being exiled from the rest of one's tribe meant certain death, it is still perfectly rational in the modern age: the aforementioned physical health consequences plus what happens if I need a friend's help for a task I cannot accomplish by myself or I end up having to stay in the hospital long-term?
Even trauma is a rational reason to be depressed. For one, going through daily flashbacks is exhausting and it is perfectly reasonable to feel lethargic and hopeless when my daily routine is largely composed of screaming at ghost-people from my past and flailing about in mental agony. It also contributes to my loneliness as it makes it difficult to connect with "normal" people or simply "behave myself" whenever I have company; this often ends in interpersonal conflict which traumatises me further, starting a vicious cycle. Is it not rational to feel hopeless when trapped in a vicious cycle? Even for external issues, such as the economy, the daily flashbacks make it extremely difficult to hold down a job - I've been fired for it multiple times - and therefore I'm finished if the next financial crash wipes out the welfare state. Is it not rational to feel hopeless when you just know that your head will be one of the first on the chopping block?
