Ignorance

Just an hour ago I was at a friend's room, waiting for him to copy something to my pen drive to me when I noticed his room mate's notes on his table.

It was a course on critical reasoning, and it was notes on logical fallacies that people are prone to.

I look down and I saw this note:

Argument from ignorance
Example: There is no proof that watches exist, therefore, they do not exist.

Immediately i felt something wasn't right. It was obvious what this was an analogy to.

There is no proof that God exists, therefore, he does not exist.

By using such a bad example, which does not clearly show what the argument from ignorance actually is, it makes me suspicious of the lecturer's intentions.

First off, the argument from ignorance is essentially a logical fallacy in which it is claimed that a premise is true only because it has not been proven false, or is false only because it has not been proven true.

The example that the lecturer give appears to be correct at first glance. Just because one cannot prove that watches exist, it is not a good enough reason to conclude that they do not exist. However, because watches do indeed exist (I hope none of you doubt the existence of watches), it is hard for anyone to relate to the point of the fallacy.

A much better example would be: There is no proof that the BigFoot does not exist, therefore Bigfoot must exist.
Or: You cannot prove that evolution happened, therefore evolution is false.

Indeed, the argument from ignorance is essentially drawing too much from too little evidence, or drawing too little from important evidence, usually because one has reasons to support one particular stance.

If anything, we have to take all the evidence as a whole before drawing conclusions. One might not be able proof that the Bigfoot does not exist, yet after years or searching, all evidence claimed to be found has been fakes, and all we can find is personal testimonials that do not always tally with each other. In other words, given all the available data, there is a high chance that the Bigfoot does not exist.

As for the watches example, it would have been more accurate if it has been phrased like this: You cannot prove that watches exist, therefore watches do not exist.

This way, the reader can clearly see that just because 1 person cannot prove that watches exist, it is not enough of a reason to conclude that watches do not exist.
In fact, if there is no proof that watches pretty safe to conclude that they do not exist.

You cannot prove that purple invisible hippos exist, therefore, they exist.:)