coining a fallacy.

Plantinga’s Fallacy Claiming that if S fails to have evidence for her belief that p, then S either doesn’t know p, or is irrational/unjustified in believing p.

Example:  “What’s your evidence that human persons have intrinsic moral worth?” 
“I have none.” 
“Then you don’t know that they do.”
“You just committed Plantinga’s Fallacy”
“Who the ef is Plantinga?”