Jon Reading brings up very good points as always and I, of course, agree with them concerning the perspective of assault. For me, it is primarily about the physical action that is necessary to be called a martial art.. Yes, psychological factors are involved and yes there is a psychological aspect to training and conflict...no doubt. But, if you strip away things down to the base elements, what controls the psychology are two things...the willingness and the ability to take physical action as necessary.
The psychological aspects or qualities are largely secondary or a by product of physicality. So, we must be willing and able to do something physical in whatever situation.
Going to the issue of the dynamic of a fight. I tend to focus on the model of OODA, observe orient, decide, and act. It is essentially a decision loop and if we understand it provides a frame work in which we can judge or assess what we do physically in a situation.
in most training is we perceive the conditions or the situation we are in when we train.. We have this idea, for example, that we are reaching for our car keys in a parked garage and we are grabbed from behind. Of we are confronted by a bully in a bar that won't allow us to back down from a fight.
Two good scenarios, but how well do we actually set the conditions up when we train? Do we assume a high degree of initial failure in our physicality? That is, does that person physically have the upper hand?
I think this is were we fail many times in our training as we assume we have more control than we do. i.e we are way, way behind in the decision loop, and we really do not have good initial actions or solutions to solve the problem physically. Barring that, we really cannot deal with the situation pschyologically nor can we really do much to "de-escalate" as we like to discuss in aikido so much.
so, we need to come up with ways to gain back that control physically. I think this is where our practices should spend 80 percent of our time. If we are doing this, then I think this is true self defense. We have lost control and we simply are working back to "stasis". This is my definition of Self Defense.
As Jon points out, once we go beyond that, well then we are entering into a phase of illegal assault. Yes, it is still assault while you are in a phase of gaining back control...the difference is I think you can call it justifiable assault.
We can even use pre-emptive assault as long as we can demonstrate that we felt that there was no other way to resolve the situation because of impending danger. That is, you "jump" the OODA loop or decision cycle and ACT before your opponent puts you behind.
However, I think there is much in the process that can be done pre-emptively that does not involve assault. for example, in the going to your car in the garage scenario.....don't go alone. Park in well lit area, if you see something strange, disrupt the cycle by going back inside the building.
Yes, these are all part of the cycle and continuum....but we don't practice these things in a dojo because common sense tells us they are not a part of the physical realm of martial practice.
So, it kind of bothers me when someone comes up with the solution set "I never got in a fight...as the ultimate self defense." and essentially uses that as an excuse to practice substandard things in a dojo where it should be primarily about the physical aspects of a fight.
If this is an area of concern for us, we should be practicing failure over and over. Understanding our physical limitations (and emotional), through being in positions that are very very bad. your own the ground, he is on your back, being choked, pinned against a wall...all those things and figure out ways to get out of them, turn the tables, and take back control.
Of course, we can also practice the esoteric stuff too that I think is interesting and fun, challenging, stimulating and intellectual as a form of budo. There is also much to be gained there as well, however, primarily we should always remember that first and foremost it is about the physical, violent nature of imposing wills.