My thoughts on defiance in general...
There always seem to be two viewpoints on this kind of thing. One would be to change how you view your child's behaviour (not viewing "defiance" as a bad behaviour, just as a difficult one in his development)- and do the best you can with some progressive parenting to meet his needs in the belief that he will eventually grow out of it. The other category (which I fall into, for better or worse) is to have "more concrete" standards and work compassionately and age appropriately, to uphold them... I think these oft-repeated stances reflect the personality, worldview and life experiences of each individual family and each parent has to decide which they are more comfortable with to have peace in their home.
From 6 mos or so on, DS2 always listened to no- til about two months ago- 15/16 mos-when he really started to become his own separate identity in his mind, and he was practicing/experimenting with using his free will. It seemed like for a few months he was on hiatus with following any of my directions ("Come here, close the door, all done nursing, etc) that he previously accepted without question. Kind of reminds me of the way he practices any new skill repetetively- like throwing/chasing a ball, climbing up and down the two steps to our family room over and over.
Now, he is again cooperating *almost* all the time. What worked for me was, if he didn't listen, going down to his level and making sure that my instructions were very clear. For him, the mere suggestion of a way besides the way he wanted to go actually provoked mini tantrums, and since he would not want to be touched when he was upset, I set him in his playpen to calm down (30-60 seconds) safely. Then, before I picked him up I would ask him "Are you ready to such-and-such"? Sometimes he would say no, get mad again, and turn away to stay in the play pen. A minute later he'd be ready... usually the first time I asked he was ready. I felt like, with this particular child, this was what worked best for me to honor his free will and nurture the independence he was seeking to employ in that, I was patient with him *to help him reach the point where he could willingly cooperate* with those things that, in our house, are absolute. He is very happy now, happier than he was those stormy months of questioning everything, because I believe he was essentially trying to understand what the limits were- and now he is content with them. (Although I realize there will be many more stages of testing the limits/exerting independence). PLEASE NOTE- if he had not had fits of anger at the idea of doing something other than what he wanted, I would have chosen a different strategy. If he had fits of anger but would receive an embrace, I would have sat with him and held him til he calmed down in my lap and was ready to cooperate. I did not choose the playpen as a punitive "time out"... it was just a place he felt safe coming to terms with cooperating.
I believe that if you wait to introduce or enforce a family standard on something, you are essentially reinforcing its opposite. I like to hold the standard out there whether or not my child is fully ready to reach it, remaining compassionate of their age and stage and the fact that they are still learning, rather than not trying and by default, setting them up for a rude awakening that all of a sudden we are changing to some new standard on a day when I deem them ready to comprehend. I guess I believe that innately they understand most of what I am trying to communicate, and it is simply a matter of them incarnating their powers to meet my intentions (when they are reasonable and meaningful- whenever I have been arbitrary or non-compassionate they have countered with obstinacy).
