On Aggressiveness

There is a lot to be said for aggressiveness in a self-defense situation.
As one wise man said "it is not the size of the dog in the fight, it is the size of the fight in the dog".  Experience tells us that in any self-defense situation, the victory goes to the one who displays the most aggressiveness quickest.

While we typically consider aggressiveness as an unconscious, automatic response of the body to real or imagined stress the "fight" part of "fight or flight response", in reality it is a reaction that can be harnessed to give us the full effect with only minimal downside.

Proper training is at the heart of the matter.  often I can see students in a drill shift their mental state into "attacker" or "defender" depending on their role in the drill.  Some do both parts like a zombie :-(, giving no energy at all for their partner to work with.  This is the worst.  Second worst is having a "defender" mentality.

In the "defender" mentality, you become a victim.  You wait for an attack and try to absorb, deflect or block it.  Many times this happens with the eyes closed or blinking, as if closing your eyes would somehow make the bad people disappear... it won't.

No.  It is important to always display AGGRESSIVENESS.  The level of violence should be proportionate to the threat involved, but with the maximum aggressiveness in every case.

In aikido, aggressiveness is demonstrated in three ways:
1) the kiai --- a loud yell at the attacker.  see here
2) the movement is always forward --- INTO THE ATTACKER
3) Atemi - the initial hit as we take control of the attacker's attack and redirect it

In Filipino Martial Arts as well, there is no defense.  There is only attacking the attacker and attacking the attack.

Attacking the attacker means proactively ending a situation when a threat is perceived.  There is no waiting for a punch to be thrown.  MOVE FIRST.  MOVE DECISIVELY.

Attacking the attack means Gunting.
When we gunting, we must imagine that we are ATTACKING THE ATTACK. Our goal is to disrupt the attacker, take the balance/structure away and end the situation in the most efficient manner possible.

In training it is very important to train aggressiveness as well as specific techniques and responses via drills.
That said, unless the teachers and students know it is a specific goal, often times it is not explicitly emphasized.  If so, students miss one of the most important tools in self-defense.

This can be trained by using drills.  One example is where the student faces increasing attack pressure (such as hits to the head with the pads).  The student should do their best to block/deflect/redirect these hits without panicking.  On command, the student should explode back at the attacker with a flurry of hits until told to "stop".  Another drill can have the student in a circle and being hit from all sides.  Similarly, the student should seek to evade/block/cover/deflect the hits.  On command, explode out of the circle to freedom, taking at attacker or two out along the way.  These types of drills should be repeated until the students can explode on command without any hesitation.

Again, the best defense is a good offense.