Objective: How can I get my dog to go to the bathroom outside more?

Which of the following solutions is more sound in terms of naive physics reasoning?

(1). Take the dog indoors more or leave him inside longer when possible to get him used to going out there, and give the dog treats when he or she does..
(2). Take the dog outdoors more or leave him outside longer when possible to get him used to going out there, and give the dog treats when he or she does..
(2).