How do you deal with someone who always has a "but"?

Bitch slap solves the problem temporarily.

But, i do this! But only to explore another perspective of the subject in question. But i don't think it's normal to always do this. But i do.

It's normal but I voted no.

Depends on which context. If the "but" is to make an excuse, then don't offer them anything to make excuses for next time.

Slap him. I hate it. Even though "but" is one of the words i say the most.

Run away from them.

In life there is duality to everything, no negative without a positive and no positive without a negative.

There is always a but if you look hard enough.

I don't know a person like this. But, <- Hahah, I said it! anyway, everything has a reason or a meaning to it, every single thing you or they do whether it's valid or illogical. Other people get scared and pussy up and make dumb excuses.

You can deal with them by being honest with them or just laughing at their cowardly instincts.