For a long time, I've insisted that it's a taste issue. Diet coke seems more bitter than Diet Pepsi. But, to be honest, it's more than that. Diet Coke is about more than the actual taste. It's also about the way that the beverage is presented. This is usually pointed out as a criticism of people who prefer one soda over another.
"You don't really prefer Diet Coke. If I put Diet Pepsi in a Coke bottle, you would say that you liked it."
I accept this and don't know why it's a criticism. It's pretty obvious that enjoyment of a drink is about more than the physical taste. Other sensations are obviously important, including smell and visual aesthetics. If something tastes wonderful but looks like a pile of vomit, I'm perfectly justified in finding it unappetizing. The same goes for cola. If the aesthetics of a Pepsi bottle disagree with me, then I'm perfectly fine not preferring it to other drinks.
But then I realized that I needed to take a further step. It's not just the whole aesthetic package, but something much bigger. If someone poured me a glass of Diet Pepsi and told me that it was Coke, I would probably claim to like it. This is because enjoyment is about something not contained in the material components of the object. The object cause of desire is something that is in the object that is more than itself. I don't simply enjoy the commodity, but enjoy it as a lifestyle and an image. When I buy a coke, I'm making a statement about that brand versus the Generation Pepsi branding that irritates me.
This is what's known as a fetish. I isolate Coke as the thing that I enjoy but it's something much more elusive that isn't constrained to the physical properties of coke itself.
The first time that Lacan proposes this still-mysterious object-cause, he illustrates it by the fetish of fetishistic perversion. It is here, he says, that the dimension of the object as cause of desire is unveiled; the fetish is not desire, but it must be there in order for there to be desire, and desire itself is going to stick around wherever it can. You see to what level the fascinating object of desire has fallen. It is no longer any old place where desire is going to stick around: it must be there. One can already, in this "be there," see Dasein, from which Lacan will characterize as the objet petit a, resonate.Kierkegaard's picture of love has a lot in common with this idea. When you make the radical leap of loving someone, it's not just about the particular properties of that person. It would be obscene to write a list of reasons that you love someone and say that that was the total basis of the way that you felt. Such an act falls short of unconditional love because if those features changed (e.g., the love of your life got in a car accident and was disfigured), your love would vanish. Love can't be reduced to any specific feature of the person in question. It's a dedication to something in the person that is more than themselves.
Even though the love-event seems to be senseless to someone standing on the outside who is not caught up in it, the perspective of the one who finds themselves caught in it imbues it with something more. It is the position that the subject takes towards an event, and not any specific characteristics of the event, that grants it its revolutionary status. To different observers, an outbreak of popular unrest can be perceived as either a meaningless lashing out (see the way that the riots that France saw last year were often interpreted by commentators in the media) or as a challenge to the coordinates of the status quo. The critical thing isn't necessarily the physical conditions that generated the unrest, but the way that someone positions themselves towards it.
In this sense, the object of the event is empty, but it is the subject's fidelity to it that grants it retroactive substance. Love for one's significant other isn't the mechanical interaction between their features and one's preferences but depends on a radical leap on the part of the subject. I recognize myself as being caught in an event that is much more than those features. Saying that one is in love for this or that reason is part of the story, but remains incomplete. The cause of my desire is something that is much more complex and irreducible to mere fetish, in spite of how important the fetish is.
To bring this back around to tasty beverages in a somewhat vulgar fashion, I suppose that that's why I like Diet Coke. Saying it's just the taste or the curves of the bottle is just an expression of commodity fetishism. The more important source of my preference is probably the piece of consumer culture that I purchase and communicate to others when I drink it and declare that it's superior to competing brands.