Hi
A quick follow-up question: Do you think it's that much easier to kill with a gun than with a machete? Don't the same factors come into play when someone decides to shoot a bunch of people for the first time as do when the goal is to chop them to death?
The same basic factors are at play. The key difference is that the resistance to killing is not an absolute thing, it's a variable and it is affected by a host of factors. The actual killing methodology and proximity to the victim plays a key part.
The more removed the killer is from the actual act of killing, and from the victim, the easier it is to overcome the resistance (and also the lower or more delayed the backlash, allowing for continued killing).
The actual act of killing itself can vary from the extreme case of killing someone by penetrating their body with your own (say killing them by shoving your thumb through their eye into their brain) or issuing an order for someone to fire a missile that flies across the world before blowing up a house.
On this scale shooting someone with a firearm would involve a lesser resistance than actually cutting them with a machete. Firstly it's a simple matter of range - with a machete you have to be close. Secondly with a machete you are physically holding the object that enters their body and kills them, whereas a person firing a gun has no physical contact with the bullet.
Distance from the victim is the second major component and pretty much mirrors what I said above - you physically need to be closer to a victim to kill them with a machete. At that range it becomes impossible to deny the pain and anguish and suffering you have inflicted on the victim. They may even make some physical contact with you.
Another aspect to consider in this specific case is how people were targeted. In terms of the above factors, with a machete it is undeniable that you yourself killed the particular person dying right in front of you. In contrast if you fire a shotgun indiscriminately into a large crowd of people you have not individually targeted anyone, and so at an intellectual level you can deny personal responsibility for the death of a specific individual.
Lastly, killing someone with a machete would typically take longer than killing them with a firearm. You pull the trigger, there's a bang, they fall down, and you move onto your next victim (they of course might not actually be dead yet, but you have dismissed them from your mind). In contrast when you kill someone with a blade you are immediately in the presence of their pain and suffering as they are initially injured. You may have to inflict additional wounds on them to kill them.
Last thing to consider is the "blowback" or the psychological repercussion of overcoming your resistance. The resistance in the machete example is more extreme for the reasons explained above, and that results in a more severe and more rapid blowback - it may occur during the actual act of killing them. As such you're more likely to be overcome with grief sooner, preventing you from continuing.
In contrast blowback from a firearm killing may be delayed or less severe, and as the actual act of killing is quicker, you're simply more likely to be able to kill multiple people before being overwhelmed by the psychological ramifications of what you have done.
A final foot note to this is that in this case the killer appears to have intended from the beginning to shoot until all ammunition was exhausted except one round which he used on himself. Knowing that suicide is the intended end result, this has a profound impact on the resistance to killing and also on the impact of the blowback (if you know you're going to die at the end of it, there's no ramification).
In contrast I have a hard time believing someone would plan to walk into a room with a machete, hack a bunch of people up, and then turn the machete on themselves.
All of these factors essentially make killing a group of people with a gun much easier than with a machete.
My personal feeling, remembering my success rate the first time I picked up a machete on the farm as a boy to chop underbrush, is that it's more easily explained as, "city boy don't know how to chop."
I don't think that's it at all. The resistance to killing is entirely independent of any ability to perform the mechanical action. Soldiers throughout history have failed to fire their weapons at the enemy despite receiving extensive weapons drill.
