My, you're touchy. Anything the mater with your self-esteem? Right, let's go through this together from the beginning. We have an ASDA product label here saying "Plant based mashed potato". This is of course absolutely hilarious to some people on here (not necessarily including you), because we all know potatoes are plants, so this is some sort of new-fangled silliness, right?
You say "I assume they're trying to say there's no butter or cream in it but it still looks like a particularly stupid tautology." Considering that the marketing people at ASDA probably earn more than me and you put together, we might take this one step further. Would these highly-paid professionals who are supported by psychologists, statisticians and whatnot really use what looks like a particularly stupid tautology and make a laughing stock of their company? Probably not. So, we might try finding out what possible reasons they have for labelling their mashed potatoes "plant-based". Are "plant-based mashed potatoes" really the same level of stupidity as "pesticide free girders"? What do mashed potatoes normally contain? Well, potatoes, of course, anything else? O yes, butter, and some people use cream or milk, which are all dairy products...[just as you said, of course].
We think a bit further, roughly along the following lines: 'This is obviously meant for customers who consider it important that what they buy is in some way plant-based. What does that epithet mean? Is that even the right question? Linguistics never tires of pointing out that
the meaning of a word is defined by how it is used [yes, I highlighted this especially for you, my scientifically-minded friend who values unambiguous definitions so much]. I know, let's google this! Ah, here's something from Merriam-Webster, who are one of the biggest publishers of dictionaries. They probably know what they are talking about. Let's see...aha, they say it's a new word, "showing greatly increased use, in a variety of settings. It is routinely applied to meat substitutes, and to non-food stuffs which contain no animal products." This seems to tie in with our supposition that it all has to do with how food is marketed. Right, let's read on..."However, over the several decades that
plant-based has been in use, it has come to mean different things to different people. Some use it synonymously with the adjectival form of
vegan, others think it is closer to
vegetarian (insofar as something
plant-based may contain animal products, such as dairy or eggs, although no flesh), while others still employ the word in a self-explanatory fashion, reasoning that any food or product which is largely based on plants deserves this label"...yeah, well, that's all sort of obvious, but in any case "plant-based" is some sort of synonym for "vegetarian" or "vegan", something to do with a need to fell that no animals were harmed. Let's keep reading..."In many instances it can be difficult to say why speakers choose to distinguish between
vegan and
plant-based; possible reasons include a perceived animus toward vegans, or the desire to be semantically precise". Well, that sounds plausible: The label "plant-based mashed potatoes" is designed to appeal to customers who want food they feel they can eat with a clear conscience as no animals were harmed in its production, but who might be wary of something labelled 'vegan' as this sounds a bit quirky and not particularly tasty. Right, we seem to have come to the preliminary conclusion that "plant-based" here is a synonym for "vegetarian" with the psychological advantage (which will manifest itself in sales figures - numbers never lie!) that it doesn't conjure up the associations with asceticism and general joylessness that "vegetarian" does. Looks reasonable to me. At first sight "plant-based mashed potatoes" might look like a particularly stupid tautology, but it isn't; it has a clearly discernible meaning and purpose, and we can all stand down. Maybe what something looks like at first sight isn't as important as whether and how it works?