Why do piggy Ralph sam and Eric deny being and the dance?

Answer 1

Jack believed the dance would keep the storms from coming, so under the threat of bad weather and Jack's manipulative nature, Ralph and Piggy joined the dance, even though they did not want to.

Answer 2

Because to admit they were involved in the dance would also be an admission that they were involved in the violent and savage killing of Simon. All four boys are in various states of self denial, they don't want to acknowledge to themselves what they actually did.

Answer 3

The four of them are still somewhat civilized and feel guilty that Simon was murdered. Putting them away from the dance helps them to deny that it was their fault and their actions that resulted in the death of Simon.

Answer 4

All of them know that they have killed Simon but they don't know for sure either since it was dark and storming. They also don't want to feel guilty for anything either.