A 21st century change of the way the word “semantics” is understood came with the phrase “arguing semantics”, and to me makes “semantic” a type of contronym, which is word that has a contradictory usage, such as the word “cleave” which can either be used to express “cutting apart”, or to express “sticking together”. In the phrase “arguing semantics”, semantics is being used to connote that the topic is of little importance, rather than specifically about meaning of words. However, semantics in philosophy is a important field of study, and is not just of “little importance”, from which theories are formulated from, such as Tarski’s Semantic Theory of Truth. When someone tells me I am arguing semantics, it is often difficult to tell which meaning of the word they are trying to express. That is interestingly enough what the field of semantics actually does deal with, the meaning of words and how they are being used in modernity (synchronically), verses how they were being used over time (diachronically).
In one case if they are suggesting my argument is “trivially unimportant”, then I generally would want to know what it is about my argument they find non-interesting…but of course if they truly feel my argument is of little to no value, they would probably just walk away, no harm no foul, with my argument unassailed. In the other case, where they are actually arguing my argument is about meanings, most of the time their statement would, in fact, be incorrect. When I state what words mean in a specific domain of discourse, I am expressing a fact which I could argue for and in that case, then I would be arguing what the semantic meaning of a word is with in a specific field, as generally understood within the field. However, I would never be arguing a word has some prescriptive meaning within the field, unless there was in fact a prescriptive meaning, such as within physics the speed of light is prescribed as being equal to exactly 299,792,458 m/s by definition. That certainly doesn’t mean we can’t describe the speed of light by other means, but merely that c is specifically defined to mean a very specific value in the domain of physics.
Logical arguments however are not specifically dealing with word meanings, unless of course someone is arguing a word has a specific meaning:
1. The speed of light is defined as 299,792,458 m/s (by definition).
2. A photon travels at 299,792,458 m/s.
c. A photon travels at the speed of light.
This is a valid and sound argument, but isn’t arguing that a word has a specific meaning, as it is accepted as premise of the argument axiomatically as opposed to:
1. Photons travel at light speed.
2. Light speed is 299,792,458 m/s (by definition).
c. Photons that travel at the speed of light, means “traveling” for the photon is at 299,792,458 m/s.
That is both logical and is arguing semantics that a word “traveling” here infers a meaning of going 299,792,458 m/s.
In ether case of the intent of the speaker, when they say “arguing semantics”, it seems to be a very puerile attempt to marginalize an argument. As when someone suggests that the argument is semantical in nature, and not worthy of evaluation, they generally fail to recognize that by doing so they have recused themselves from weighing in on the argument, and the argument remains intact.