[The Godfather]

The word "but" in a sentence like this:

"The much-touted hardware encryption of the iPhone 3Gs is but a farce."

What is its purpose? What's the difference in meaning between that sentence, and the same sentence without the "but"?

By context, one could guess it might be a contraction of "nothing but". Any academics willing to answer this one?

[iMOTOR]

I think usage of that word in this particular sentence is simply a matter of antiquated style. At one time it may have been fashionable to use it as a contraction for nothing but.

[The Godfather]

So. Is it a grammar form of the nineties?

[iMOTOR]

I seem to remember an author from the 1800s using it that way. I’ve never heard someone say it that way in recent history. Clearly it is improper and illogical.

[ide3308]

I think it's an emphasis on the 'farce.'

[turtle777]

They produced too many "but" back in the day, but they need to use them, albutit it might sound stupid.

-t

[RAILhead]

It's funnier if you replace farce with fart.

And add another "t" to but.

[iM@k]

Originally Posted by RAILhead 

It's funnier if you replace farce with fart.

And add another "t" to but.

But would a farce of any other spelling smell as sweet?

[Chuckit]

You've guessed the meaning correctly — it means "merely," or "nothing but." I'm sure you've seen some movie where one of the characters, having been asked to do some great task, says a line like, "I am but a humble servant/plowboy/whatever." The use in your sentence is less cliched, but it's the same meaning. You're also right that it serves no apparent use in that sentence but to make it sound pretentious. I would have omitted it. It's not like somebody might misinterpret the sentiment as being, "The encryption is a farce — but also an awesome feature!"

[Spheric Harlot]

Originally Posted by iM@k 

But would a farce of any other spelling smell as sweet?

What mumblemumble through yonder mumblemumble breaks?

('Tis the moon)

[Oisín]

Originally Posted by iMOTOR 

I seem to remember an author from the 1800s using it that way. I’ve never heard someone say it that way in recent history. Clearly it is improper and illogical.

Improper and illogical? Not at all. ‘But’ has been used in this way for over a thousand years. Originally, it was used as a complement to a negation, but (as in many other cases), the negation waned and was generally suppressed in certain constructions. It’s the exact same meaning (‘if not, unless, other than’) as is found in the constructions ‘who/what/when/etc. but …’.

It’s also quite parallel to constructions in many other languages, though the negatice is still found in most of them. For example, in French (where, technically, que is not ‘but’, but has the same function): l’encryption de l’iPhone n’est qu’une farce, or in colloquial French without the negative, as in English: c’est qu’une farce. Or in Latin: quid est pietas, nisi voluntas grata in parentes (“What is piety but a willing service to one’s parents?”, from Cicero). Or even in Irish (where ach is both the normal word for ‘but’, but also, with a negative, the normal word for ‘only’): níl criptiú crua-earraí an iPhone ach ina fhronsa.