It struck me last night that what we're all really up against in this thread is a logic problem. This is going to be a long post, but I'll do my best to make it worth your time and hope you will read on. Who knows? The information may be useful for something later.
It's been a while since college but, far as I can tell, the argument that the matching unidentified DNA found in two different places on JBR's clothing proves that she was killed by an intruder is a logical fallacy.
In deductive reasoning, an argument is valid when both premises are true, and it is not possible for the conclusion to be false when both premises are true. The most famous example is:
1. All men are mortal.
2. Socrates is a man.
3. Therefore, Socrates is mortal.
The one you'll remember from high school if you didn't have algebra right after lunch is:
If A = B
and B = C
then A = C
Assuming for a moment that the two DNA samples of interest here absolutely match, it is logically valid to say, for instance:
1. Unidentified DNA matching the same profile was found in two different places on JBR's clothing. (True)
2. The DNA of JBR's family members is known. (True)
3. Therefore, the unidentified DNA described belongs to someone who is not a Ramsey.(Valid)
It is not logically valid to say (for example):
1. The unidentified DNA described did not come from the Ramseys. (True)
2. It has been proved that the unidentified DNA described was deposited at the time of the murder. (False)
3. Therefore, the unidentified DNA described belongs to JBR's killer. (Invalid)
OR
1. It is proven fact that the DNA described could only have come from JBR's killer. (False)
2. It is proven fact that said DNA did not come from the Ramseys. (True)
3. Therefore, none of the Ramseys killed JBR. (Invalid)
OR Construct your own argument:
1. No one here but BlueBottle knows for sure who killed JBR. (True)
2.
3. Therefore,
Just razzin' you, BB : ) :seeya:
Moving right along.... There is a second type of argument using inductive reasoning. This is the type we use every day. One advantage of the inductive argument is that the logic is less rigorous so it's easier to construct. One disadvantage is that it is more prone to fallacy. This means that even the strongest inductive argument can never be the foolproof, all-other-bets-off-the-table creature that a valid deductive argument is.
Here's an inductive argument:
Since the beginng of recorded time, the sun has risen in the east. Therefore, it will continue to rise in the east.
Pretty strong.
Here's another one:
Our unspayed outdoor cat has never had kittens. Therefore, she will probably never have kittens.
Surprise!
Below are two examples of inductive arguments specific to the Ramsey case, and those of you who have stuck it out this far can decide how strong or weak they are and how they compare.
1. In the overwhelming majority of cases where a minor child is found violently killed in the home, one or both parents had a role in, or have knowlege of, the child's death. Since JonBenet was found violently killed in her own home, there is a very high probability that her parents, who were at home at the time of the murder, were involved in her death or know who was.
2. The increasingly sophisticated science of DNA mapping and identification continues to solve cold cases, sometimes for murders that occurred even 40 years before. Unidentified DNA matching the same profile was found in two different places on JBR's clothing, and the profile has been entered into CODIS. Although no identification has been made so far, there is a very high probability that the DNA will one day be ID'd, and we will then know who killed JonBenet Ramsey.
So where I am going with all of this? Here's the wrap-up:
-- Deductive arguments can be good or bad (well constructed, poorly constructive), but all are either valid (airtight) or invalid (open to further argument).
-- Inductive arguments can be strong or weak, but even the strongest inductive argument is never airtight ; i.e., it cannot prove something to a certainty, only to a degree of probability.
-- A valid deductive argument is always superior to an inductive argument. (the "A Smith & Wesson beats four aces." principle).
-- An inductive argument cannot become a deductive argument or carry the vaildity of one.
-- A string of facts alone does not constitute a logical argument.
It is a logical fallacy, then, to claim that an inductive argument makes an absolute case. And, while it is possible to do, it is not nice to beat fellow Inductivites over the head with a logical fallacy. As long as one is in Inductionland, the matter remains arguable - period, end of story ; ) This is not a matter of opinion. It is a principle of logic.