David E. Oliver asked whether Wiccans would cast a curse to ” stop
someone who is going to committ murder?  Sometimes doing harm is only
way to fight evil. Do pagans believe in evil?”  I promised him a thread, and here it is.

This raises a number of interesting questions.  First, the Wiccan rede
says “An ye harm none, do as ye will.” The rede is not a complete ethic.  It does
not define “harm” and it does not say when harming is appropriate.  It’s
a very good rule of thumb, one that humanity as a whole would benefit from
adopting, but it is not a guide in all situations.

With that preamble, yes, I would use magick against a person planning
murder.  Not a curse – that would not stop the murder.  A binding of
some sort would be the appropriate method.

Do these things work?  They can, but one done well takes considerable
discipline and focus and there are counter measures – and this kind of
thing can go on and on.  Interestingly, a firm disbelief in magick
provides a shield against it because both are mental forces.  So a
binding  is not as good as calling the police, which is almost always a
far better approach. 

As to “evil,” a great deal depends on how it’s defined.  I discussed this issue a lot in my book Pagans and Christians, and to some degree in my part of Beyond the Burning Times.  (Shameless plugs.) 

Very briefly, most Pagans, and certainly this one, do not believe in
some source of absolute evil, like a Christian Devil.  On the other
hand, there are malevolent actions by people that can be legitimately
described as evil.  Not the people, the actions.  And there are in my
experience pretty unpleasant entities on the spirit level that may or
may not be evil, but certainly mean people harm. 

I do not use “evil” as a synonym for ‘dangerous,’ or “a bad outcome” or “ill will” and I think the frequent conservative Christian
attitude that all unpleasantness is due to some ‘fall’ is a sign of
spiritual childishness.  On the other hand, there is nasty stuff out
there on the spirit plane, and anyone who ignores basic safety issues
while messing with it is foolish.

Happily, very few people, including Pagans, venture into those
dimensions or do things that bring themselves to the attention of what ‘s out
there.  The analogy I use is hiking in grizzly country.  Not many
places where that’s an issue, but where it can be you should be
prepared.  And yes, I speak from experience.