magic can you cast a counter spell without a target

[Chameleon]

can you cast a counterspell without a target in magic?

[Twanos]

no. Anytime a card say it does X to target, then you must have a legal target to cast the spell.

In this case it's says counter target spell, therefore, there has to be a target spell or you can't cast it.

On a side note, some cards are worded so it's spell does X to up to Y target....

In this case because the spell has an up to number but no minimum you can cast it naming 0 as the number of targets for Y.