At one time*, Yagami Soichiro states, "It is the power to kill that is evil, not the person who has it." Later, his son remarks to Ryuk that he has contrarily considered the note "the best thing that ever happened to me".

Did the death note create Kira, or was it just the perfect killing tool that Yagami Light couldn't resist? Did it just rationally prepare him to do what he had always been capable of, or did it enable him to commit an act that he would otherwise have never been capable of? Well, that's what this essay will try to address.

In our very first glimpse of Light, he idly thinks "this world is rotten" while in class. Soon after, he encounters the death note. At first he disbelieves, calling the idea behind the note "stupid". However, he seems to be preocuppied with it, and later he tells Ryuk "that notebook has a power that makes you want to try it".

When he finally seems motivated to use it, he starts to think critically. Part of his criteria for the ideal victim is "someone whose death doesn't matter." When the murderer Kurou appears to have died, he seems visibly disturbed, but mutters, "It could be a coincidence... one person isn't enough" and concludes he should verify it by killing another person "that deserves to die". Later on, he thinks "Nobody would think anything if a few guys like him died" when considering his classmate. And walking in the city, he wordlessly remarks, "Looking at all these people... I start to think the world would be better off without all of them."

But upon recognizing the note's authenticity, Light has to hold back his own vomit as he leans against a wall for support. He thinks, "I've killed two people." He remembers the murder on the news and thinks, "Who cares if he died...?" He then thinks, "But what about the second one...? He didn't deserve death." After a moment, he reconsiders, "No... It's what I'm always thinking. This world is rotten. The rotten should die", his face half-shadowed, and stands up straight.

He loses sleep that night as he's shown to wrestle with his own moral conflicts. He realizes that he can "do it" (cause "the rotten" to die) with the death note. However, he finds he has difficulty committing murder. He wonders if he should quit, but tells himself, "No, I can't quit. Even if it costs me my mind and my life... Someone has to do it! Things can't remain as they are!" His deliberations continue into the next day and early classes. Finally, he decides that there is no person so incredible he could trust them with the notebook, and concludes, "I'll use the death note... and change the world!"

Over the next five days, he loses four kilograms and has more trouble sleeping. He continues to write down the names of criminals "to cleanse the earth". Now, what to make of all this?

Evidently, he possessed the belief that "this world is rotten" before he ever knew of the note. In his own words, "It's what I'm always thinking." Judging from the way he's depicted to think in chapter one, his determination that "the rotten should die" followed at least partially from that concept. So, the base of his desire to become Kira existed before he ever could have been influenced by the note.

He was able to consider murder rationally and had even developed criteria for what type of murders would be acceptable. (It's unreasonable to conclude that he was able to develop those beliefs "on the fly" upon obtaining the note, even though we were only able to observe Light's thoughts on the matter after he'd obtained it.) Therefore, he was capable of seriously pondering murder and did not consider murder universally unacceptable before he ever encountered the death note.

Since Light had not killed before he obtained the note, we can't know for certain if it enabled him to consciously kill another person. However, Occam's Razor states that "entities should not be multipled beyond necessity"; that is, the simplest explanation is the best one. Why attribute the act of murder to the death note alone, when it's a known fact that people premeditate murder all the time?

A person could falsely demonize the note out of empathy for his fellow man, and his desire to believe in the human individual could motivate him to deceive myself. Light's father is that person. Judging from all that I've described, Light had the mind of a killer, and there's no reason to believe that he could not commit murder. Kira is a function of Light, and the death note cannot be held responsible for his decision to kill.

*Chapter 22.