“Nothing is objectively good for human beings; or at any rate, if anything is, there is no way to know.”

“Is that so?  Then put your finger in this candle flame.”

“I’ll do no such thing!”

“Why not?”

“Because it would hurt, as you well know.”

“So?”

“So I don't like pain, all right?”

“Why don’t you?”

“I see what you’re trying to do.  You want me to admit that pain is bad.  Have it your way: Pain is bad.  According to taste.”

“What do you mean, ‘According to taste?”

“I mean that it’s merely my subjective preference.  I make no claim that it holds in any objective sense.”

“You mean that it’s like your preference in flavors of ice cream?”

“Exactly.”

“What flavor do you like, by the way?”

“Chocolate.  Why?”

“Do you like vanilla?”

“Hate it.  You still haven’t told me why you’re asking.”

“Give me a moment.  Have you always liked chocolate?”

“No.  When I was a little boy I hated it.  I liked vanilla.”

“Doesn’t it distress you that you changed your mind?”

“Why should it?”

“Then it doesn’t?”

“No.”

“Why not?”

“Because it’s just a subjective preference, as I told you.  It makes no difference.”

“Do you find it upsetting to imagine yourself enjoying vanilla again in the future?”

“Of course not.”

“For the same reason, I suppose.”

“Yes, for the same reason.”

“Put your finger in this candle flame.”

“What’s the matter with you?  I told you, I don't want to get hurt.”

“I thought you might have changed your mind.”

“Why should I change my mind about a thing like that?”

“Just thought you might.”

“Well, I’m not about to.”

“But it doesn’t bother you to think that you might.”

“What?”

“I mean that you wouldn’t have any problem about becoming a masochist and seeking out painful experiences.”

“Are you trying to insult me?”

“Not at all.  Do you mean you don’t fancy becoming a masochist?”

“Of course I don’t.”

“But how is this subjective preference different from the other?”

“What do you mean, ‘different’?”

“Well, it doesn’t matter to you whether you prefer chocolate to vanilla, or vanilla to chocolate, so long as you get what you want at the moment.”

“True.  So?”

“Yet it does matter to you whether you prefer pleasure to pain, or pain to pleasure.  See the difference?”

“Yes, I see it now.”

“Good.  Now when you were explaining your tastes in ice cream, I understood you to mean that the reason it doesn’t matter to you whether you prefer chocolate to vanilla, or vanilla to chocolate, is that your preference for one over the other is, in your own view, purely subjective.”

“Drat.  I see where this is leading again.”

“Tell me.”

“You want me to say that if, whenever I regard my ordinary preference as purely subjective, I have no higher-order preference about what preference to have, then, whenever I do have a higher-order preference about what preference to have, I must regard my ordinary preference as other than purely subjective.”

“Right.  Go on.”

“And so in the ease of pleasure and pain, where I really do prefer to go on preferring pleasure, it must be my view deep down that my preference for pleasure over pain is objectively reasonable.”

“Well?”

***    *    ***

Do not reproach me for the brevity of this slice of conversation.   I know full well that no self-respecting philosopher would give in so quickly; that is not the point.  I am only offering an illustration, and you need not agree to any of the claims to which the speakers agreed.  All I ask you to recognize is that this conversation belongs to the genus of rational argument.

Seeing that, if you don’t like the way it was conducted, you may write a better one yourself -- or have a real one.