This is true in everyday conversational English usage of the terms, but in the context of philosophy, they acquire additional meaning and connotations.
It's kind of like how when we (programmers) say "functional programming" we have a very specific concept in mind. If a lay person read and interpreted that phrase literally, they would probably not have the same concept in mind. They might even ask "What is functional programming? Isn't all programming functional? How can there be non-functional programming? etc."
What we mean when we say it is a style of programming that is often contrasted against object-oriented or procedural programming styles. We have supplanted the ordinary English meaning of these words and attached additional connotations and meaning to them. It's the same thing happening with the terms above in philosophy.
It's exactly the other way around. It's lay people using 'relative' to mean 'subjective'.
In philosophy, 'relativism' is sometimes short for 'cultural relativism' as in the case of moral or epistemic --- but relativism in this sense is short for one highly specific 'relative' relation (ie., a relation to culture).
And lay people use 'objective' to mean 'universal', which it doesn't. Cultural relativism is consistent with an objective metaethics.
> It's exactly the other way around. It's lay people using 'relative' to mean 'subjective'.
I've actually found the opposite - people will often use "subjective" when they really mean "relative". They often unwittingly imply the relation to culture. I think it's far more rare to find a lay person using the term "subjective" to precisely refer to the philosophical meaning of the word.
> And lay people use 'objective' to mean 'universal', which it doesn't. Cultural relativism is consistent with an objective metaethics.
It's true there is a distinction there between "objective" and "universal", but do you feel that in most contexts, when someone says "objective" they are also implying "universal" and the onus is on them to elaborate on the distinction when that implication doesn't hold? (I guess asking for both the case of lay people and the one for philosophers).
I think lay people lack the vocabulary to be specific about their claims, so for anything that is said, there's several possible reconstructions of it.
As for philosophers, objective means "of the object", and subjective means "of the subject".
In different domains these play different roles. In ontology, objective means that a property belongs to the object under study. In epistemology, it means that a claim is true because it describes the object (rather than the subject, etc.). In morality, it means both; ie., that moral truths are true due to properties of objects (including people); and those objects have morally-relevant properties.
The word 'relative' simply means that something depends on something else. 'Relativism' is a specific kind of relativity: that of some phenomenon to an 'intersubjective' perspective. Eg., a culture.
In the lay mind, because most things are relative (eg., the interpretation of these words to the english language), they are also subjective -- because these terms have become profoundly confused.
In all cases of 'objectivity' in every sense you also have 'relativity', since objects exist in relations to other objects.
What lay people mostly mean by 'relative' is subjective; ie., they're committing the genetic fallacy of the form: since understanding X requires a perspective in which to evaluate it, X itself must be a (inter)subjective phenomenon.
ie., they're saying that since understanding is relative to a perspective so is what is understood. This is the irritating fallacy popular amongst those who go around abusing the term 'relative'.
What lay people mostly mean by 'relative' is subjective; ie., they're committing the genetic fallacy of the form: since understanding X requires a perspective in which to evaluate it, X itself must be a (inter)subjective phenomenon.
ie., they're saying that since understanding is relative to a perspective so is what is understood. This is the irritating fallacy popular amongst those who go around abusing the term 'relative'.
I'm not sure if I find this particularly convincing. I think most lay people are actually talking about the thing itself rather than their understanding/perspective on the thing.
Maybe this is something that a study could shed light on, if we're able to construct a survey that can give us some insight into how lay people are using/abusing these terms.
It's kind of like how when we (programmers) say "functional programming" we have a very specific concept in mind. If a lay person read and interpreted that phrase literally, they would probably not have the same concept in mind. They might even ask "What is functional programming? Isn't all programming functional? How can there be non-functional programming? etc."
What we mean when we say it is a style of programming that is often contrasted against object-oriented or procedural programming styles. We have supplanted the ordinary English meaning of these words and attached additional connotations and meaning to them. It's the same thing happening with the terms above in philosophy.