It seems to me like you're supposed to be able to try to attack people while unarmed in Pathfinder, but I'm not sure you actually can.
You threaten all squares into which you can make a melee attack, even when it is not your turn. Generally, that means everything in all squares adjacent to your space (including diagonally). An enemy that takes certain actions while in a threatened square provokes an attack of opportunity from you. If you're unarmed, you don't normally threaten any squares and thus can't make attacks of opportunity.
Let "you threaten the square" be A
Let "you can make a melee attack in the square" be B
Let "you are unarmed" be C
Let "you possess no exceptional unarmed abilities" be D
What am I doing wrong?
(In words instead of symbols)
The rules seem to say that you threaten squares if you can make melee attacks against them. The rules also say that you don't normally threaten squares if you're unarmed. Does this indicate that a character who is unarmed in that 'normal' sense is unable to make melee attacks, since they don't threaten squares?
As SSD pointed out, my error is in encoding the first sentence as B->A as opposed to (B.-C)->A, and, as he also pointed out, there are many, many, many more conditionals involved were we to represent it this way truthfully.