It doesn't need to make sense. Sticking knifes in other peoples bodies doesn't make sense either, yet it happens every single day. So what makes sense to you is a pretty poor yard-stick to evaluate a case like this.
Two fundamental reasoning errors here.
Firstly, people sticking knives into each other does make sense, in the only sense that matters. It's a known and far from uncommon human behaviour. Any rational and informed person is going to expect people to threaten other people with knives thousands of times per day, and to murder other people with knives tens of times per day at least.
Secondly, a rational person estimates all of these probabilities in light of the known facts, specifically that Meredith Kercher was found murdered with a knife.
Given the known facts, what are the odds someone murdered Meredith Kercher with a knife? 99.9...9%. The only other alternatives are incredibly unlikely.
What are the odds that Amanda Knox carried around a kitchen knife in her bag to defend herself? Massei's proposition was that the odds of this were >51%
just because Raffaele was into knives, but that doesn't survive even a moment's scrutiny. What percentage of young women whose boyfriends are into knives carry a kitchen knife in their bag? I'd guess <1%.
What are the odds that a young woman, her boyfriend of six days, and a local crook she had met once at a party and seen once at her place of work would team up to molest and murder one of the young woman's friends? Well, it's hard to estimate seeing as it has only ever happened once in the history of the world if it ever happened at all, but it's got to be <1% until some more evidence of guilt comes in.
What are the odds that Raffaele could participate in a three-way sexual assault and murder, get his DNA on the metal hook of the bra clasp and on absolutely nothing else, no part of Meredith and nothing in the room? I don't know. Murderers have left no DNA trace in the past, but it's not usual. Say <50% to be really generous.
What are the odds Amanda could participate and get her DNA on nothing except the handle of the knife she supposedly carried around with her, and then leave her DNA on the handle while removing all but a picogram trace of Meredith's? I don't know either, but I think this is even more unlikely.
So we're chaining together a whole bunch of suppositions, none of which make any sense or even rise to the level of being more likely than not... where is the good evidence that's going to make a rational person buy this chain of absurdities?
It's incredibly telling that no pro-guilt poster whatsoever will even try to answer this question. They have no coherent theory of the crime, and they don't even have any coherent idea what evidence convinces them of Knox and Sollecito's guilt!
How you can believe X to be true yet be able to give no sensible account whatsoever for
why you believe X to be true, and still consider oneself a skeptic, baffles me.
