Absence of Evidence is NOT Evidence of Absence

I apologize in advance, but a lot of this post is going to be copied and pasted from Wikipedia. Any professor I've ever had would highly disapprove of this. =) This will also be a rather long post...

Basic Definitions

Fallacy-an invalid argument that appears valid, or a valid argument with disguised assumptions.

False Dichotomy-a type of logical fallacy that involves a situation in which only two alternatives are considered, when in fact there is at least one additional option.

Argument from ignorance (or appeal to ignorance)-a fallacy in informal logic, where "ignorance" stands for "lack of evidence to the contrary."

Informal fallacy- an argument whose stated premises fail to support their proposed conclusion.

Argument-an attempt to persuade someone of something, by giving reasons or evidence for accepting a particular conclusion.

Absence of evidence-the absence, or lack of, any kind of evidence that may show, indicate, suggest, or be used to infer or deduce a fact.

Evidence of absence-evidence of any kind that can be used to infer or deduce the non-existence or non-presence of something.

Argumentum ad Ignorantiam---Appeal to Ignorance

This type of argument asserts that a proposition is true because it has not yet been proven false (the kidnapping).This represents a type of false dichotomy in that it excludes a third option, which is that there is insufficient investigation and therefore insufficient information to prove the proposition satisfactorily to be either true or false (What EVIDENCE has the public seen that allows one side to arrive at this conclusion so readily? What the police are privy to, we are not...You can take their word that no kidnapping occurred, but they are humans and capable of the same logical fallacies as any one of us).

Arguments that appeal to ignorance rely on the fact that the veracity of the proposition is not disproven to arrive at a definite conclusion. These arguments fail to appreciate that the limits of one's understanding or certainty do not change what is true (Sometimes law enforcement gets it wrong). Whatever the reality is, it does not “wait” for human logic or analysis to be formulated. Reality exists at all times, and it exists independently of what is in the mind of anyone. (Assertions by law enforcement do not change reality. Facts are facts...)

This fallacy can be very convincing (clearly) and is considered by some to be a special case of a false dilemma or false dichotomy in that they both fail to consider alternatives. A false dilemma may one of two forms:

• If a proposition has not been disproven, then it cannot be considered false and must therefore be considered true.
• If a proposition has not been proven, then it cannot be considered true and must therefore be considered false
  

These arguments ignore the fact, and difficulty, that some true things may never be proven, and some false things may never be disproved with absolute certainty (I often wonder, what evidence would be left behind if someone opened a door, walked into a home, and removed their child?). The phrase "absence of evidence is not evidence of absence" can be used as a shorthand rebuttal to the second form of the ignorance fallacy (i.e. P has never been absolutely proven and is therefore certainly false.).

 

Argument from incredulity/Lack of imagination

Arguments from incredulity take the form:

1. P is too incredible (or: I cannot imagine how P could possibly be true); therefore P must be false. No one could have entered the home or took Ayla without waking anyone or getting caught.
2. It is obvious that P is true (or: I cannot imagine how P could possibly be false); therefore P must be true. Justin bought a life insurance policy, Ayla had her arm broken and suffered other injuries. The pattern of abuse escalated, so he harmed Ayla and caused her disappearance.

These arguments are similar to arguments from ignorance in that they too ignore and do not properly eliminate the possibility that something can be both incredible and still be true, or appear to be obvious and yet still be false (things are not always what they seem). The allegations/assumptions in red boggle my mind. Stranger things have, and do happen, every single day!

 My Thoughts..

We have one of each type of false dichotomy in this case; ironically, both arguments are coming from the same side. This is ironic, because these terms/definitions are usually used in regard to a debate of some sort or to something that is in contention. The fact that both logical fallacies come from the same side explains why there can be no reasonable debate about Ayla's disappearance.

Referring to the bullets above, we see these two things have been alleged or put forth by the other side:

• Justin, or someone in the DiPietro household harmed Ayla and then hid her body. This has not been refuted by the "facts" in the case; therefore it cannot be considered false has to be considered true.
• Ayla was not kidnapped. There is no evidence of this happening; therefore it cannot be considered true and must be considered false.

After reading the above discussion from Wikipedia, it is obvious that these are false dichotomies based on the scant "facts" that have been released so far. There are absolutely other alternatives. To be specific, one could argue that there has not been enough investigation, or that sufficient information has not a) been provided to the public or b) been gathered from the investigation.

I feel that it is important to reiterate the fact that these so-called appeals to ignorance can be very convincing, but that one's certainty and one's understanding have limits. Reality does not change, so believing strongly that one scenario is more plausible than another, will not make it so.

When it comes to the kidnapping claim, which is central to this case despite MSP ruling it out, we don't know if law enforcement found no evidence because it does not exist (evidence of absence), or if they simply lack proper means of detection (absence of evidence).  

Note: I am not implying at all that their investigation was flawed in any way, but insufficient means of detection could refer to any number of things...such as the inability to smell B.S.

What are your thoughts? Beware, if you cannot discuss them rationally, you should simply click the red 'x' in the corner of your screen!