How many of us actually take this into consideration when attacked? Did you actually know when you applied force for self-defense that this also would influence whether your actions would be judged legal vs. illegal?
This also promotes just how important it is for anyone teaching or learning self-defense to get the knowledge and apply it to your practice and training. You may have assumed that these type of things don't matter; mistake.
Example, there was an article not long ago about a woman who was standing in a parking place so as to hold it until her boy friend could bring the car around the block to park. This is not an uncommon action by many in big cities especially when parking is a premium. Anyway, while the boy friend was going around the block another man pulled up and told her to get out of the way. The woman explained, etc.
To shorten the story the guy got out of his car and apparently decked her. He claimed that the woman attacked him first. She was knocked out and he was arrested. She was about 120 pounds and he was about 215 pounds. She was a small person and he was about 6' 1 or 2". The age was not mentioned so we don't know how far apart their ages were.
Here is where I would have added to the "Size, Strength and Age" the word "gender." I do believe that "gender" would also be of high consideration in a self-defense strategy.
With out any additional information I would "assume" that in front of a Jury those twelve folks would see both parties, if she lives, and say, "Hm, small woman, big man; stronger man vs. average strength woman; age makes no difference; woman vs. man?"
How can a man who is obviously much larger and stronger with a definite advantage as to perceptions and social behaviors to be of greater ability who applied his greater ability against one with less using force that is apparently much greater than necessary to defend, if it was actually defense against her say, slapping him, could not be guilty of assault?
So, you can readily see that size, strength, age, and GENDER do matter. I don't think I could "articulate" anything well enough to overcome my actions and convince a jury of twelve that I was justified in putting a woman in the hospital for a parking space! Right?
p.s. considering the story I used for an example, the need to train and practice to control the monkey brain seems really critical for at least the male species. I say this because in the story above it seems that guy is using the self-defense strategy in desperation because it would appear he allowed his monkey brain to run the show resulting in the assault on the woman. Monkey Brain Training, yea, sounds good to me.
Miller, Rory. "Facing Violence: Preparing for the Unexpected." YMAA Publications. New Hampshire. 2011.