"He started it!" is a grade school defense, it isn't a legal defense.
This has been coming up a lot, in the manuscript I'm working on with Lawrence, in various videos people have asked me to watch, in some training I am planning and the video shoot in September. If you are defending yourself, it is because you are losing.
What does that mean? That the bad guy picked the range and his position. That he probably moved in such a way as to hamper your response (amazing how real knives are almost always used after grabbing the head or your arm and unbalancing and how few people practice against that). That before you are even aware things have started, your structure is compromised and you have taken damage.
Whatever your best move is, how well will it work if you are already folded over with your wind knocked out, wedged into a corner and with the bad guy riding your closest arm and slamming strikes into the back of your head and neck? 'Cause that's the baseline, my friends.
And you can fight from there... but you have to practice fighting from there. There are ways to use a compromised structure or the momentum of being slammed.
Bad guys have it easy. Almost any technique from any system will work if you are the bad guy. You can pick the range, the target and the orientation. From target shooting to soft arts, almost anything works if you can choose the when and where. Only the bad guy ever gets to choose that.
Sparring or dueling is really a contest between two bad guys. It starts at a range when there is a huge choice in how to close and where to close and what to do. It's contested, (which makes it a contest) but the essence of being attacked is the utter lack of those kinds of options.
When we teach self-defense, we tend to forget this, teaching techniques from a solid base with clear vision. When we pressure test in the ring we lack respect for how huge the difference is between prevailing in a contest and recovering when a human predator has stacked everything in his favor.
Distance, stance, blocking... that's stuff the bad guy will have time for, but probably won't need. If you have all that, if you have time to get into a proper fighting stance or set up a shoot, you may not be the bad guy... but you can almost certainly walk away.