KEEP YOUR HANDS UP.

The "guard". The hallmark of every fighting style on the planet.  To the savant, an immediate indicator of a fighter's school.  But it serves other purposes as well.  To an untrained attacker, one's guard may serve as a deterrent. "Uh-oh, this guy knows some shit", is the most common reaction.  Many use it to bluff their way out of a confrontation (Hell, I did it when I was a kid, to great effect), while others use it to initiate conflict.

Skip to 1:08, or just watch the whole thing ;)

So formalities aside, the main reason to keep your hands up is to avoid this:

Getting knocked the F*CK out. 

A good guard protects one from an opponent's attacks while simultaneously keeping you ready to mount an attack.  Any guard that favors offense at the expense of defense leaves it's user "unguarded".  Conversely, an overprotective guard hinders the ability to seize an opportunity to strike.  An effective guard dynamically balances offense and defense.

Now we often hear of someone being "guarded" or "having their guard up" in day to day interaction.  This would be an example of an overprotective guard.  If you walk around from day to day and people can see that your hands are up, it puts them in a confrontational posture.  However, just to protect your well being and personal space, (I believe) it is necessary to be on guard without looking like you're on guard.  Especially in negotiations.  Be prepared to protect your interests and command respect from the opposite party, and be prepared to take advantage of any opportunity that presents itself.  The key to this "relaxed guard" is knowing yourself.  You must be aware of how comfortable you are in the situation, and that will determine how much you will take, and how much you can give. (I sense that this will be it's own blog entry)

I'm not going to go into how to hold your guard, because there are hundreds of variations on the basic guard, and they all serve the same purpose.

Now the "relaxed guard" is actually a higher level of guard because it requires more confidence by the user because it actually "invites" an attack by creating the illusion of an opening in the defense.

Ali was famous for fighting with his hands down, and as you see, it invites attacks which leave the opponent open for a counter.

Bruce's version further illustrates the point.  These guys were confident in their speed, reaction, reach and timing so they could violate this cardinal rule of fighting.  They were also confident in their assessment of their OPPONENT'S ABILITY. (Yet another blog to come)  The end of this clip leads into the final level of "KEEP YOUR HANDS UP"...

It's called "PUT YOUR HANDS DOWN".

The ultimate form is formlessness, to paraphrase Bruce, Musashi, and many other enlightened artists through history.  I learned this through Ninjutsu's SHIZEN NO KAMAE (natural stance)

It's literally standing with your arms at your side.  Depending on the situation and the opponent, it is either the ultimate taunt/invitation to attack, or the ultimate deterrent.  Once you have mastered the guard, you can basically forget the guard.  This is one of the great ironies of life that I love running into repeatedly.

Now do not forget: SHIZEN IS THE REPRESENTATION OF ONE'S TOTAL CONFIDENCE IN THIER CONTROL OF A SITUATION. It should never be used as a bluff. Ever.

So once again, the application of the "KEEP YOUR HANDS UP" concept is left up to the user.  Whether physical or metaphorical, you want to protect your self and your space, while remaining able to strike out and seize the day.