Sometimes in an informal debate you will encounter people who dismiss your argument by saying, “Well that’s just your opinion.”  This is nothing more than an attempt to relativize your conclusion without rebutting your arguments.  There are a few ways you can respond to this.

The first is to ask, “Isn’t it just your opinion that my view is just my opinion?  If we ought to dismiss opinions because they are opinions, then your opinion should be dismissed as well.”

The second is to say, “No, this is not just my opinion.  I have provided reasons for thinking my opinion is actually true.  If you would like to try to rebut my reasons you are more than welcome to do so, but do not dismiss my view with a mere hand-waving as if I have merely provided you with an assertion, rather than an argument.”

The third is to say, “Yes, I have an opinion, but so do you.  This much is obvious.  But what follows from that observation?  The question is not whether we have opinions—we all do—but whether we have an informed opinion.  If we both have informed opinions, then the question becomes Whose opinion is better informed?  We determine the answer to that question by evaluating the strength of our respective arguments.  I have presented you with my argument, and now I am interested to hear your response to that argument.”