There are some interesting cases which demonstrate that it is fully possible for a person to use a word competently in most situations but still fail to grasp its meaning, or at least all of its meaning. The example I have in mind specifically here is Putnam’s elm/beech example. Putnam points out that we my be quite competent in using the words “elm” and “beech” in many contexts, and yet be totally unaware of the features that define them as types of trees. Thus we don’t really understand what the words “elm” and “beech” mean, despite our competence in using them in many situations. (Note: What I have to say here regarding this case is not meant to be a response to Putnam. It could be a response to Putnam, but there are far better responses available. The better response is simply to point out that his opponents don’t claim that the representation completely determines what is represented, and, more importantly, that it is the representation and not what is represented that is part of consciousness.)
The first thing to notice is that the elm/beech case is in a way compatible with use determining meaning. Obviously someone who doesn’t know the defining features of elms and beeches will be unable to pick them out from other trees when they come across them. Thus a complete understanding of the meaning of a word could be identified with the ability to use that word correctly in all circumstances. But this still leaves us with a problem; in most circumstances understanding elms as just “a kind of tree” is sufficient to use the word correctly. Thus it would seem that by knowing that definition we must have grasped most of the meaning of the word, since we are able to use it correctly in most situations, when it seems pretty obvious that we have only grasped a part of the meaning of the word, certainly not most of it. We can justify that claim by noting what the purpose of the word is. The purpose of the word elm is to distinguish one kind of tree from others. Thus the meaning of the word elm is tied most closely to the parts of it that allow it to fulfill its purpose, namely the distinguishing physical features of the elm. And so by not capturing those features someone who understands elm only as “a kind of tree” has not grasped most of the meaning (or at least not the core meaning) of the word.
This naturally leads to a more pressing problem: how do we now determine what a word means in the context of a community that shares a common language. Normally we simply appeal to the average or majority understanding of the word. “dog” means dog, we say, because most people in that community have associated with that word in their minds a representation that represents dogs. But, as cases such as “elm” show, it may very well be the case that the majority of the community does not in fact grasp what we are accustomed to thinking of as the meaning of the word. There are basically two ways to deal with this situation. One is to concede that the meaning of “elm” just is “a kind of tree” within that community, and that it only acquires its useful meaning, as picking out a particular kind of tree, within a sub-community who grasps the fuller meaning of “elm”. Although technically flawless I think this is not a very useful move to make. First of all it is hard to identify the sub-community, except by their understanding of the meaning of “elm”. And secondly the sub-community and the larger community have no problems talking with each other, even about elms (most of the time). So it seems unnatural to pick this sub-community out as distinct when they seem anything but. (In contrast to a sub-community who understands certain technical terms, which they are unable to use in communication with the larger community.) I propose then that we instead re-define how we determine what a word means in the context of a community from “the average meaning” to “the most common meaning that most would accept as a suitable meaning”. This definition completely avoids the problem because even if most people understand “elm” only as meaning “a kind of tree” they don’t accept “a kind of tree” as an acceptable meaning for “elm”. By understanding an elm as a kind of tree they understand it as being distinct from other trees in certain ways, because that is what being a kind of tree entails. Thus by understanding that it is a kind of tree it becomes impossible to accept as a meaning for elm simply “a kind of tree” because it doesn’t say what kind of tree the elm is.
Finally we come to the question of how complicated, exactly, is the partial meaning that most people associate with “elm” and “beech”. In his original example Putnam implies that it must be fairly complex, because people would deny that a beech is an elm. This implies that for “beech” most people also associate with it “not an elm”, “not a fig tree”, and so on. But I do not actually thing this is the case. You see most people would probably also deny that a “beech” is a “fagus grandifolia”. This is not because they have some understanding of the terms that motivates them to reject the identification, because “fagus grandifolia” is the scientific name of the beech. Rather it is because people have some intuitive rules about how meaning works, and one of those is that different words usually don’t mean the same thing. Thus they deny that elms are beeches not because the meaning they associate with the terms distinguishes them, but because they have never heard the two kinds of tree explicitly identified, and thus the default assumption that they are different stands. This kind of process is also at work when the meaning of a word is best captured by “the kind of …” or “the thing that …”. In both cases people have assumptions about what kinds of things are (defined by being fundamentally similar in some way) and what things are (have a certain unity) that govern how the word is used without such rules ever making it into the meaning itself. The meaning then remains relatively simple, but some of the concepts involved with it may be complex.