I have stuck to that convention on this website (though I'm sure I slip up occasionally). I was a little surprised then to see Bushmills' latest print campaign which declared its product "the daddy of whiskies" while the label in the same picture identifies the bottle as containing "Irish whiskey".
I reckoned a Balderdash and Piffle-style investigation was warranted so I asked Bushmills about this interesting juxtaposition. I received a very thorough and thoughtful response. In summary, to underline that Bushmills is the "daddy" of all whiskeys (Irish, Scotch, American, etc.) they adopted the spelling of "whisky" that is not conventional in Ireland.
Below is the full reply from Bushmills.
We did have quite a few debates around the two options 'whiskies' and 'whiskeys' when we were developing the campaign and these debates are still going on!
However, let me try and explain our decision.
The convention today is that Irish whiskey is spelt differently from Scotch whisky. As far as 'Irish whiskey' is confirmed, in the plural form, 2 options are accepted: whiskeys and whiskies. Both are correct, even if we tend to prefer the former spelling (whiskeys) as it retains the specific 'Irish' spelling.
Again, I'd like to stress that this is a matter of convention - and therefore ultimately personal choice. It is worth noting that many Scotch 'whisky' brands did use the 'whiskey' spelling up until the second half of the 20th century... just as Irish brands also used both spellings quite liberally too. To be 100% accurate, I believe that today the legal definition for Scotch Whisky only authorises and recognises 'Scotch Whisky' as a legal descriptor ('whiskey' cannot be used on Scotch labels' - I believe).
Things get a bit more complicated when one is referring to 'all whisk(e)y', whether it is from an Irish, Scottish - or even American, Japanese etc - origin. Which spelling is appropriate then?
Well, we have opted to use the 'standard' spelling 'whisky' in this case, and its plural 'whiskies'.
In the present case of our campaign, it is worth noting that Bushmills ancestry does not only apply to the world Irish whiskey... but actually to all whisk(e)y - as (as I am sure you know) the secret art of distilling, and thus the 'recipe for whisk(e)y' originally came from Ireland to Scotland... and then spread to America and beyond.
This led us to the conclusion that our slogan should read "The Daddy of (all) whiskies", rather than "The Daddy of whiskeys".
Usually when we are talking about Irish whiskey - and particularly our own Bushmills products - we use the plural 'whiskeys' – you will see this on our website. Our American colleagues have chosen to tread another path, and when talking about Irish or American whiskey, they will stick to the spelling with an E in the singular form, but will use the plural 'whiskies'.