Jackie Strauss recently posed a question that elicited from me a longer response than I think she needed. Jackie wrote:
“Would you please clear up something for me that’s been plaguing my mind for years. People speak of ‘healthy foods’ all the time. My impression was that we who eat these foods will be the healthy ones for it. Shouldn’t those foods that are good for us be called healthful foods, meaning ‘health-giving’? And doesn’t healthy mean ‘health-having’, so to speak?”
“Please tell me the proper use of healthy and healthful. I’d really appreciate it!”
No one has worked out all the rules of semantics, but we (linguists) know that they are different from the rules of grammar. Three of the things we know are: (1) You do not need a grammatical connection for a semantic one. Semantic rules operated on what makes LOGICAL sense, not grammatical sense. Example: “An occasional sailor walked by.” What is an occasional sailor? The semantic rules automatically assign the modifier occasional to the verb, not the noun, so we semantically interpret this sentence as “A sailor occasionally walked by.”
(2) Another semantic rule is that cognition adjusts the meanings of what we say. “John ran over a dog coming home,” doesn’t make sense literally. We know John drives a car home, so we don’t have to say, “John ran his car over a dog coming home.”
My favorite example of this filling in to make sense is something that happened in my home for decades. My wife would say, “It’s Thursday,” and I would take the garbage out (like a trained puppy). She wouldn’t have to repeat over and over every week, “It’s Thursday and Friday is garbage pick up day; please take the garbage out.”
Healthy food falls in this category. We know food can’t literally be healthy so our brain looks for another connection between healthy and some other word in the sentence and—Bingo!—it quickly finds it: healthy for humans.
(3) Semantic rules operate on semantic features, not grammatical ones. “Harry’s a pig!” doesn’t imply that Harry has a snout and curly tail, only that he is either “dirty” or “greedy”. These are semantic features that we have (unfairly) attached to the meaning of the word pig. That pigs have snouts and curly tails are lexical features of pigs and, if Harry really is a pig, and both speakers know it, the listener will interpret the sentence with the full definition. However, if we know that Harry is not a real pig, that doesn’t stop semantics from looking for other features in the definition of pig that do fit.
By the way, language often treats animals unfairly. I’ve treated the subject before. But to summarize, “Sheila’s a cow, dog, cat, (clothes) horse,” doesn’t put these animals in any more of a good light than it does on Sheila.
Do you have to ask interesting questions? I’m sure this is more than you wanted to know. I’ll have to make a language blog entry out of this.