One of my Facebook friend posted this. Sharing anonymously with permission.

The Echo Fallacy: When you shout "hello!" in a cave, and upon hearing the echo, conclude the cave walls are saying "hello" to you. More generally, when you put a certain idea into your environment, have it reflected back to you, and conclude that the reflection shows the idea originating independently from yourself.

Some examples:

* What Scott Adams calls "laundry list persuasion". This is when you say: "Maybe bigfoot videos are blurry and questionable, but there are so many of them! Why would there possibly be so many unless bigfoot is real?" Well, the answer is simple: bigfoot believers promote the idea of bigfoot, which prompts people to create fake bigfoot videos. The volume of bigfoot videos is merely a reflection of the belief in bigfoot. Similar logic applies to UFO videos, examples of pizza shops with spirals in their logos as evidence of a conspiracy, and the compilation of grievances against Jews over centuries. This is also related to apophenia, and the streetlight effect.

* When you bully someone about a quality they supposedly have, until they retort, sarcastically: "Yes, I totally have that quality! I'm just the biggest possessor of that quality on the face of the planet, dingus! Now leave me alone!" Whereupon you say they've admitted to it.

* Saying: "That guy over there loves <group>! Hey, everyone in <group>, go be friends with that guy!" Then, when some members of the group believe you and flock to that guy, saying: "See? I told you he liked them."

(I'm probably coming up with my own name for a concept that someone else has already given a name. If so, help me out.)