This scenario you describe pushes very hard on the distinction between moral guilt and legal guilt, at least in American law. Are we debating Knox’s legal culpability or moral culpability?
Well, it would still be illegal.
That’s why I specifically reference American law, which contains no general duty to rescue. That is one of the differences between English-descended Common Law, and French-descended Civil Code (which the common model in most of continental Europe).
I’m going to do a probability estimate for Knox and Sollecito having discovered and encouraged the attack. I’d do it in response to one of brazil84′s comments, but I’m already waiting on him to respond to some other questions and don’t want to sidetrack him.
Let’s start with the prior probability that Knox and Sollecito would witness the murder. Knox and Kercher lived in the same apartment, and Knox and Sollecito spent a lot of time together. Let’s call it .2
Neither Knox nor Sollecito meet the criteria for Antisocial Personality Disorder or any of the FBI dangerous individuals criteria. What should we call the probability that such a person, upon witnessing a violent attack on an acquaintance they have no motive to harm (the prosecution having established no motive) would stand back and encourage the attacker? I’ll call it >.0001. So if you have two individuals, the chance that they’d both be the sort of person who would hang back and encourage the attacker is >10^-8. But both of them would probably expect the other person to consider this behavior crazy and horrible, much like a person is less likely to commit actual murder in front of another person who they don’t know to be sympathetic, so I’ll assign a probability of .1 that if both were the sort of person to encourage the attacker, either would make the first move to start doing so. So at this point we have a probability of about 2x10^-10.
Factor in the mutual failure of Knox and Sollecito and Guede to implicate each other; I’ll assign this the same .05 probability that I did before. So now we have a probability of >8x10^-12.
If brazil84 assigns .85 probability to the prosecution’s account being correct, and .9 probability to their involvement, (I believe he may have been simply giving this as an example rather than actually asserting this,) then let’s suppose that the remainder of the probability lies in Knox and Sollecito being physically present and encouraging the attacker, but not entering the room or participating themselves. How much weight would we have to give to the prosecution’s evidence against them to get from our current probability to 5%? Their evidence would have to be more than 6.2x10^9 times more likely given Knox and Sollecito’s guilt than given their innocence.
As I stated in my earlier comment, I think that crediting them with a likelihood ratio of 50 times, including Knox’s mannerisms at the scene, is generous to their case.
Some additional thoughts on the arguments of the prosecution...
As I said in my first probability analysis, the arguments the prosecution put forward are mostly in the form of “This action seems more suspicious for an innocent person than a guilty person.” But for much of their case, I think even that is giving them too much credit. Let’s look at some examples.
The three-second phone call from Knox to Kercher. This is unusual behavior, right? Well, I’ve done this more than a few times myself, but I agree, it is pretty unusual. So how much weight would I assign that evidence?
None. The question is not how unusual the behavior is, but how much more unusual if she’s innocent than if she was involved in the murder. If I know that Amanda Knox was going, later that day, to come across Meredith Kercher being attacked, and encourage or participate in the attack, the three second phone call will not be any less confusing to me. Stalking and incessant phone calls are certainly more easily explained in light of a murder, but I know of no evidence whatsoever to suggest that murderous inclinations and unusually short phone calls are associated, nor can I think of any particular reason they would motivate one.
The time at which Amanda Knox claims to have woken up. The Massei-Cristiani report finds suspicion in the fact that Knox claimed to have gotten up at 10:00-10:30 AM that day, while her roommates characterized her as an early riser. For a person to violate their established sleep habits is unusual, although still normal enough that their say-so is generally enough to establish it as probably true absent additional reason to doubt them. I am personally not an early riser, but this morning I got up and left the house for a walk at 6:00 AM, while the stars were still bright out (which is in fact what got me thinking about the prosecution’s report in the first place.) But Amanda Knox was a murder suspect, doesn’t that give us additional reason to doubt her claim?
Well, no. Whether she was up at 10:30 or hours earlier has no bearing on the strength of her alibi. We know that the murder didn’t happen in the morning, and we know that she was in other places later in that day prior to the murder; it’s not as if she failed to establish that she ever left the house. Being involved in the murder doesn’t give her any additional reason to claim that she got up at 10:30.
Combined with misrepresentations and mistreatments of forensic evidence, including claims like the pattern of glass being inconsistent with a break-in, which was found to be simply false when tested, a large part of the prosecution’s body of arguments does not represent any weight as evidence at all.
That’s why I specifically reference American law, which contains no general duty to rescue. That is one of the differences between English-descended Common Law, and French-descended Civil Code (which the common model in most of continental Europe).
I’m going to do a probability estimate for Knox and Sollecito having discovered and encouraged the attack. I’d do it in response to one of brazil84′s comments, but I’m already waiting on him to respond to some other questions and don’t want to sidetrack him.
Let’s start with the prior probability that Knox and Sollecito would witness the murder. Knox and Kercher lived in the same apartment, and Knox and Sollecito spent a lot of time together. Let’s call it .2
Neither Knox nor Sollecito meet the criteria for Antisocial Personality Disorder or any of the FBI dangerous individuals criteria. What should we call the probability that such a person, upon witnessing a violent attack on an acquaintance they have no motive to harm (the prosecution having established no motive) would stand back and encourage the attacker? I’ll call it >.0001. So if you have two individuals, the chance that they’d both be the sort of person who would hang back and encourage the attacker is >10^-8. But both of them would probably expect the other person to consider this behavior crazy and horrible, much like a person is less likely to commit actual murder in front of another person who they don’t know to be sympathetic, so I’ll assign a probability of .1 that if both were the sort of person to encourage the attacker, either would make the first move to start doing so. So at this point we have a probability of about 2x10^-10.
Factor in the mutual failure of Knox and Sollecito and Guede to implicate each other; I’ll assign this the same .05 probability that I did before. So now we have a probability of >8x10^-12.
If brazil84 assigns .85 probability to the prosecution’s account being correct, and .9 probability to their involvement, (I believe he may have been simply giving this as an example rather than actually asserting this,) then let’s suppose that the remainder of the probability lies in Knox and Sollecito being physically present and encouraging the attacker, but not entering the room or participating themselves. How much weight would we have to give to the prosecution’s evidence against them to get from our current probability to 5%? Their evidence would have to be more than 6.2x10^9 times more likely given Knox and Sollecito’s guilt than given their innocence.
As I stated in my earlier comment, I think that crediting them with a likelihood ratio of 50 times, including Knox’s mannerisms at the scene, is generous to their case.
Some additional thoughts on the arguments of the prosecution...
As I said in my first probability analysis, the arguments the prosecution put forward are mostly in the form of “This action seems more suspicious for an innocent person than a guilty person.” But for much of their case, I think even that is giving them too much credit. Let’s look at some examples.
The three-second phone call from Knox to Kercher. This is unusual behavior, right? Well, I’ve done this more than a few times myself, but I agree, it is pretty unusual. So how much weight would I assign that evidence? None. The question is not how unusual the behavior is, but how much more unusual if she’s innocent than if she was involved in the murder. If I know that Amanda Knox was going, later that day, to come across Meredith Kercher being attacked, and encourage or participate in the attack, the three second phone call will not be any less confusing to me. Stalking and incessant phone calls are certainly more easily explained in light of a murder, but I know of no evidence whatsoever to suggest that murderous inclinations and unusually short phone calls are associated, nor can I think of any particular reason they would motivate one.
The time at which Amanda Knox claims to have woken up. The Massei-Cristiani report finds suspicion in the fact that Knox claimed to have gotten up at 10:00-10:30 AM that day, while her roommates characterized her as an early riser. For a person to violate their established sleep habits is unusual, although still normal enough that their say-so is generally enough to establish it as probably true absent additional reason to doubt them. I am personally not an early riser, but this morning I got up and left the house for a walk at 6:00 AM, while the stars were still bright out (which is in fact what got me thinking about the prosecution’s report in the first place.) But Amanda Knox was a murder suspect, doesn’t that give us additional reason to doubt her claim? Well, no. Whether she was up at 10:30 or hours earlier has no bearing on the strength of her alibi. We know that the murder didn’t happen in the morning, and we know that she was in other places later in that day prior to the murder; it’s not as if she failed to establish that she ever left the house. Being involved in the murder doesn’t give her any additional reason to claim that she got up at 10:30.
Combined with misrepresentations and mistreatments of forensic evidence, including claims like the pattern of glass being inconsistent with a break-in, which was found to be simply false when tested, a large part of the prosecution’s body of arguments does not represent any weight as evidence at all.