I do not understand the theory therefore it cannot be true.
Personal argument that states "I don't understand it therefore it cannot be true"
This is an arbitrary way of rejecting any argument and evidence. Dealt with by showing how effective some theories that are not widely understood are. You may not understand the mathematics and engineering involved in getting a man to the moon. However, the theories were used to get mankind to the moon and back and it would be unreasonable to reject them simply because you don't understand them inspite of the evident successful application of them.