“It takes a thief to catch a thief.”  The scribes were using this way of thinking when they accused Jesus of working with devils.  They said because he could call demons out of others he must be possessed of demons:  A sort of 'like attracts like' theory.  Being a demon and knowing how demons work would in their thought be a help in calling out demons.  But Jesus says that he can destroy demons because he is the opposite of demons.  His ability to destroy demons comes not from demons but from the Holy Spirit.
 
A man will not help you steal from him and destroy his house; a thief would have to subdue the man first before he could destroy the man’s belongings.  Satan will not help call demons out of possessing people; the prince of demons must be subdued before his demons can be stolen from their possession of people and destroyed.  He’s not going to help destroy his own.  The evil don’t want to destroy evil.  They want it to flourish.  Destroying demons is not in their best interest.  Because Jesus the opposite of evil, he is able to subdue Satan and destroy the demons.  

The scribes are erring in several ways in their analysis of the situation.  They insinuate that Jesus can cast out demons because he is one, when of course demons would not want to destroy their own.  He would have to be the opposite of demons to destroy them, and that would make him good instead of evil.  So by saying he is possessed of demons they are in fact blaspheming against the Holy Spirit (and Jesus says that is an unforgivable sin).  Jesus is not possessed of the devil, he is filled with the Holy Spirit.  He doesn’t get his demon-destroying powers from the devil himself, but instead from the Holy Spirit.  The scribes are therefore calling the Holy Spirit the Devil.  Blasphemy for sure.

The basic message of the theory and examples seems to be that evil increases evil and destroys good, while good increases good and destroys evil.  So it’s not that it takes a thief to catch a thief, it takes a good person of pure heart to destroy evil.  An evil person will not destroy evil, so it’s the job of the good to do it, and by doing so to increase the good in the world.