You're not even talking about the same thing: the parent talks about piracy from an ethical point of view. Meanwhile, you reply with the physical point of view, saying the item is an exact duplicate that cost nothing to produce.
Representation doesn't mean a damn thing. It doesn't justify behavior.
Ethics is grounded in physical reality, that is sort-of where the buck stops -- at least it seems a better place than anywhere else. Surely an ethical evalution of an act depends on what the act is.
What makes an act bad? If, for example, you say stealing is bad, and are asked why, you can reply that someone loses something -- they could do things with it before, but no longer can. There is a sense of harm, in basic physical terms that we can all pretty much agree upon, simply because we all share the same basic physical condition.
But what if it were possible to steal something without taking anything away from someone -- i.e. the basic physical effect is different. Is that still bad? In what way could it be? You could just institute a rule proscribing such an act anyway, and so breaking the rule might seem bad superficially. But that would be like ruling that no-one can go out in the sun on wednesdays -- surely at some point someone will ask why. And there would not seem to be a good answer.
That is the way copying is different from taking. Because, at bottom, it does not do anything harmful, and is in fact positive. And that is why people are probably likely to have some underlying sense that copying is morally OK.
Sure there will, but it depends on whether you are empathetic to the condition of other human beings. A small software vendor sells their product. In effect, they're saying, either pay for a piece of software, or do without it. I could violate that contract, but then I'd be an asshole, because they asked for payment, yet I went and took it without paying.
I wish to treat other human beings with respect, especially creators. I may hate copyright, but that doesn't mean I take it out on creators. Their works enrich my life in ways I never would have imagined, and I'm pleased to be able to support them. Jason Fried of 37Signals had a quote recently where he mentioned that, in the case of good products, people are happy to pay for them.
I say this as a software developer and one who is not libertarian in the least.
Wouldn't books, then, only be "worth" the cost of the paper on which they're printed? How does making something digital automatically destroy any inherent value?
But look at it this way, for anything digital the supply is infinite. We currently have legal methods of restricting the supply and some attempts at software or digital methods of restricting it. But even so, the difficulty we've had stamping out illegal piracy is a testament to how artificial and fragile these methods are. With truly infinite supply, the price will always be zero. Why should I pay for something I can create copies of with 'cntrl+c' and 'cntrl+v' ? The only thing that leads me to pay for basically anything is that I can't simply recreate it on my own. The day 3D printers reach the versatility of Star Trek replicators is the day a price based market economy will collapse completely. With infinite supply, there's no need to pay for anything.
Competent business owners, managers and technical people making decisions about the implementation of software are very interested in the value of that software and its value to business is exactly why we have an economy that exchanges money for these things.
There are some cases where it is possible to limit the supply of digital goods, and this is best seen in software where access to the code can be limited or the code can be written to be restricted in some way, especially in compiled software or web applications. But this, too, can often be hacked.
Note, I'm no fan of free markets. I think they are an enormously clumsy tool for linking 'price' to 'value'.
The only reason price based markets even work for any other sort of exchange is because there is limited supply. With anything digital the supply is inherently unlimited.