The counterspell rules in Pathfinder say some spells can be used to counter other spells (like, say, Darkness can counterspell light spells). But does this override the regular counterspelling rule? In short, can Darkness still counterspell Darkness?
(Note: I'm on smartphone, the ask page doesn't tell me if this question is already asked)
Counterspells says, "It is possible to cast any spell as a counterspell," then, later, continues, saying, "Some spells can counter other specific spells, often those with diametrically opposed effects" (emphasis mine). These other spells that can be countered by a specific spell are in addition to the spell being able to counterspell itself. (Also see this question.)
From the PFSRD on counterspelling (emphasis mine):
To complete the action, you must then cast an appropriate spell. As a general rule, a spell can only counter itself. If you are able to cast the same spell and you have it prepared (or have a slot of the appropriate level available), you cast it, creating a counterspell effect. If the target is within range, both spells automatically negate each other with no other results.
Specific Exceptions
Some spells can counter other specific spells, often those with diametrically opposed effects.
Unless the spell's description explicitly says that it can't be used to counterspell itself, then it can.
