Reproduced with permission from an essay originally, and fully, published at DEATH NOTES: an online source for Death Note Analysis and Discussion
(links at the end)
Disclaimer: This is a fan essay, only for fun on my part with the hope of generating discussion. I'm well-aware that characters in any form of media are always open for interpretation, and this is just mine.
Light Yagami certainly has a reputation among the fandom, and that reputation isn't founded for pointlessly. The justice-toting boy-genius murdered thousands of people, most of which without so much as batting an eye. And he doesn't regret a single one.
On the contrary, he probably views each as a job well done. It isn't just the killing, either. Light claims each victim with boyish enthusiasm and possesses a childish demeanour that leads him to be competitive to the point of taunting the condemned with a sinister smile and dancing on their grave (literally, if he gets worked up enough). Yes, that's the Light Yagami we know, our unforgettable protagonist of Death Note.
But the aforementioned facts are not all there is to Light Yagami, and it's a slam to the complexity - and, I emphatically insist, realism - of his character to assume as such merely because he kills. 'Killer' and 'sociopath' are not interchangeable words. The nature of the killing has to be taken into consideration. As far as the victim is concerned, murder is murder is murder, but not as far as the perpetrator is. The immediate fact of the matter is that sociopaths are, as a rule, self-focused and unable to empathize with the world or the people around him. This contradicts the very nature of Kira's legacy. Certainly there's the fact that Light was a bored, under-challenged genius in a society where he functioned solely on outward appearances and achievements, and certainly there's no doubt that a part of Light was perhaps waiting for the opportunity to test himself. But I honestly cannot conceive how this in any way discounts the fact that the reason Light took the opportunity he did was out of his zealous sense of idealism.
We know for a fact that Light has a societal conscience, beyond mere conditioning (if that were the case, Light wouldn't possess even half the passion that he does). The first chapter/first episode of the series is exclusively about Light's convictions. First, the shock at perhaps having actually taken a person's life, and then the total horror when he's tested it again and realized that he's killed people and yes, it's his fault. The anxiety he feels, that he's capable of feeling, does inexcusably deny him from the title of sociopath. Light is so disturbed by his actions that he can't eat, can't sleep, loses ten pounds in the first week and looks as though he's about to throw up. And finally, the resolution: doing this could make the world a better place. "Even if I sacrifice my mind and soul," Light states (even predicts). "The world is rotting. Someone has to do it." Light even acts initially under the impression that a Shinigami is going to come take his soul as soon as he's found, and when Ryuk arrives he's surprised that he's not going to be punished. Agree with his methods or not, it wouldn't be wrong to call Light's ambition selfless, wanting to "protect the weak" and "make a perfect world" without, as far as the text writes, asking in return for anything conventional such as money, sex, or political power (which also separates him from being a dictator, by definition).
Some argue the sincerity of Light's resolve as being only an excuse to jump at the chance to ease his boredom. I don't personally think that's fair, but nonetheless, the very fact that Light experiences such vivid anxiety before impulsively engaging in such risky behavior already excludes him from the title.
Now to get technical. "Sociopath" isn't a medical term, and though it has general uses it's not a proper diagnosis. When talking about sociopaths/psychopaths in the psychology field, most often we're talking about Antisocial Personality Disorder. The brief definition as listed in the DSM-IV is "The essential feature for the diagnosis is a pervasive pattern of disregard for, and violation of, the rights of others that begins in childhood or early adolescence and continues into adulthood." Sure, that's pretty vague and by that sentence alone, I'd agree without a doubt that Light is quick to violate the human rights of others, in particular the right to life (but let it be stated that the same can be said of L, Near and Mello). But the criteria goes beyong that. First, we can't quite call Light an APD at the beginning of the series - one has to be an adult aged at least 18. Furthermore, APDs ought to have a history of conduct disorder (breaking the law, inappropriate actions, truancy, running away from home, etc) since before the age of 15. I think it's safe to say that the Yagami's golden boy who so emphatically values the law hasn't even come close. Also, APDs are known for drug and alcohol abuse, which again, does not apply...
DEATH NOTES is an invaluable resource for those who like a bit of academia in their reading of the Death Note manga. Largely inactive now, its archives nevertheless contain a rich bounty of timeless essays written during the period when Death Note was first coming to the attention of international audiences and readers. The site's essayists emanate from varying disciplines within the academe, with less formal - sometimes downright flippant - pieces interspersed for flavour.
The excerpt above was republished here with permission from DEATH NOTES' editor Jennifer Fu.