one infers a conclusion based on the absence of  statements or evidence rather than on presence.

It assumes that someone's silence on a matter is  proof of ignorance or an implicit agreement with  

some position, which is not a valid assumption  since silence can be due to many other reasons.

Everyday Example:

A teacher asks the class whether anyone  disagrees with the proposed solution to  

a math problem. No one speaks  up. The teacher then concludes,  

"Since no one has said anything, everyone  must understand and agree with the solution."

In this case, the teacher's conclusion is  based on the students' silence. However,  

the silence may not indicate agreement or  understanding; it could be due to other  

factors such as intimidation, apathy, or even the  students' desire to avoid a longer discussion.  

Silence is not a reliable indicator of consent or  concurrence, and assuming it is can be fallacious.