4X4 Vs 6X6 Deck Posts

[Vern]

Should I use 4x4 or 6x6 deck posts to go into the ground and support my deck? Will treated 4x4s rot and collapse?

 

[Wildlife]

I would use 6"x6" treated just for the added strength offer,you never know what maybe added on the deck years to come also snow loads etc.