Q. My puppy refuses to walk outside on the leash. This only happens when we're outside... Is it stubbornness or fear?
A. It is never stubbornness. Dogs are not stubborn, they can't be. Dogs do not generalize well, and dogs display fearful behavior that appears to be stubbornness. Absolutely NEVER force this dog to walk outside when he is uncomfortable with doing so.. the more you force him to do it, opposition reflex - the more he will resist. The more he resists and is forced into it, the less he learns about being comfortable, and the more he becomes fearful of you and of the situation.
What you can do is carry extremely high value treats outside with you. Things like cooked white meat chicken, cooked fish, turkey pepperoni, turkey bacon, diced ham, mozzarella cheese sticks - all cut up into tiny little pea-sized pieces. You can also use peanut butter in a squeeze tube. First, put on the leash indoors and begin feeding him the treats. Help him make positive associations with having the leash put on. Then, take the leash off, and start over in 10min. Put the leash on, feed treats, walk to the door, open the door, feed treats, close door, take off leash. Start over in 10min. Put on leash, feed treats, go to door, feed treats, open door, feed treats, go outside, feed tons of treats and praise. Keep Titus in his comfort zone. If he doesn't want to go far, just feed him tons of treats where he IS comfortable going. Make sure everything is calm/happy/positive. I bet in a week of doing this, he will be happy with walk further and further all of the time. If ever he is uncomfortable, feed him lots of treats for being a brave boy, and then turn around and go back home. It's all about keeping him in his comfort zone.. it's all about remaining within his threshold and never forcing him to feed uncomfortable.
This is very common for puppies. The world is scary! It's brand new to them, and it's up to you to make their interactions and discoveries positive, happy, calm, and to never force them into anything.