What is meaning? This simple question is at the heart of philosophy of mind. Mentality and meaning have always gone hand in hand, and philosophers have tried to give an account of meaning for thousands of years. Despite the many spirited attempts, a concrete understanding of meaning has been elusive in philosophy, and a broad consensus is no where to be seen. It’s a devishly complicated question to ask what the meaning of meaning is; it boggles the mind as to how to even go about answering the question. Although it is difficult to give a straight-forward definition of meaning, I do believe, contra Socrates, that giving examples is helpful in the art of producing a rigorous definition for a concept.
Philosophers have often focused on meaning at the linguistic level, wondering how the phrase “the cat is on the mat” means that the cat is actually on the mat. Moreover, what is the practical import of the statement? What does it mean to tell someone the cat is on the mat? If the cat belongs to no one, the import is probably zilch. But if the owner of the cat has been looking for it for days, then the import of stating where the cat is is likely to be highly meaningful. From an evolutionary perspective, it seems like the practical import of a linguistic statement is more developmentally basic, in both a phylo and ontogenetic sense. In other words, meaning comes first, then language. But this pushes back the question, what is nonlinguistic meaning?
The question of nonlinguistic meaning is tied into the question of nonverbal mental content. Linguistic meaning is usually talked about in terms of propositional content e.g. the content of the statement “the cat is on the mat” is the state of affairs of a cat being on a mat. So verbal content is relatively easy to make sense out of, because we can understand the conceptual content in terms of the implied propositional content, which can be spelled out in terms of beliefs and desires. If I don’t know where the cat is and I am looking for the cat, then someone telling me that the cat is on the mat will update my belief system such that I will, ceteris paribus, be motivated to go look on the mat, and will actually look. This is a fairly orthodox way of accounting for linguistic content. But what about nonverbal mental content? How can we make sense of that?
The question is philosophically vexing in that it’s difficult to use language (the medium of philosophy) to talk about mental content that exists independently of language. One way to get a better sense of nonverbal mental content, and thus nonverbal meaning, is to ask which creatures “have” nonverbal mental content. Let’s start with unicellulars like bacteria. Does a bacterium have a “mental life”? Not in the traditional sense of the term, since it seems strained to say that a bacterium believes anything, and having beliefs has long been a traditional criteria in distinguishing creatures with mentality from those without. Whereas we could, if we wanted to, adopt an intentional stance and say that when the bacterium senses a sucrose gradient a belief is formed by the bacterium that this is indeed sucrose it is encountering. But we know deep down that the “sensing” of the sucrose is entirely constituted by the physical-chemical nature of the bacterium. The sensing and digestion of the sucrose is entirely reactive and mechanistic. The bacterium’s “decision” to devour the sucrose based on its “belief” is entirely mechanical. The belief-forming talk is just that, talk. We do not really think that the intracellular machinery’s job is to form beliefs; its job is to perform biochemical functions that aid in the continuation of the bacterium’s metabolic existence.
But although the bacterium does not have beliefs, and thus does not “have” propositional attitudes except those we ascribe to it, it still makes sense to say that bacterium has a mental life, however dim compared to more complex creatures. For what is mental life? I claim a creature has a mental life just insofar as there is something it is like to be that creature. And, following Heidegger, I claim there is something it is like to be a creature just insofar as that creature “lives in” a phenomenal world. “Living in” in a phenomenal world is not like a spatial sense of “in” as in the case of the pencil being “in” the box. Living “in” a phenomenal world is more like being-in-the-world where being-in-the-world is a matter of (1) having concerns and (2) living in an environmental niche. A bacterium has concerns insofar as it is “concerned” about its own survival. Its whole existence is constituted by a desire to stay alive, to maintain its autonomous living. It “does” this in virtue of its complete biochemical nature. But its biochemical nature is organized in such a way as to constitute a machine which has a homeostatic equilibrium and the means by which to maintain that equilibrium despite perturbations from a changing environment and breakdowns in the stability of the internal mechanisms. So because the bacterium is “concerned” about itself in virtue of having its physical structure, the bacterium therefore lives in a phenomenal world insofar as it lives in an environment. The bacterium’s world is such that what is meaningful to the bacterium is that which enables it to keep on living. Thus, sucrose is meaningful to the bacterium because it affords the possibility of digesting it for maintenance of its homeostatic equilibrium.
We have then a foundation of meaning upon which to build more complex types of meaning. Basic nonverbal mental content, and thus basic nonverbal meaning, is based around autonomy. The bacterium is an autonomous machine because it gives itself its own principles for behavior based on its nature. These principles are properties of its organization as a physical object. One of the principles is concern oriented insofar as the maintenance of a dynamic nonlinear homeostatic equilibrium is the fundamental concern. And as we said, if you are concerned about something, then you live in a phenomenal world. If you live in a phenomenal world, you “have” phenomenal experience (where having is understand to be a metaphor, and not a literal “having” of an object like having a hammer in your hand). And if you have phenomenal experience, there is something it is like to be you. Thus, there is something it is like to be a bacterium.
But notice how the bacterium has no nervous system. If my argument goes through, then we can conclude that looking for the neural correlates of phenomenal experience is a completely misguided enterprise that is bound to fail. However, since I have been trying to argue that phenomenal experience and consciousness do not overlap, this means that we can still coherently look for the neural correlates of consciousness. But the NC of phenomenal experience is completely misguided, because, as I have tried to establish, there is something it is like to be a bacterium, and bacteria do not have nervous systems. If I am right, then neurophilosophers trying to pinpoint the NCs of phenomenal experience have been barking up the wrong tree. For the fundamental principle of mental life is not consciousness but living in a phenomenal world i.e. a world of real value and meaning, where entities are encountered as significant. Rocks do not live in a phenomenal world. There is nothing a rock is concerned about. It does not care if you break it in two. There is nothing it is like to be a rock. A rock has no mental life. But what a world of difference in the bacterium! The bacterium is alive. It has concerns. It lives in an ecological (i.e. phenomenal) niche. Whereas the rock does not strive to stay together in a particular organizational pattern, the bacterium does. Sucrose means nothing to a rock, for nothing means anything to a rock, but things matter to bacteria. Sucrose is meaningful to bacteria.
And that is the meaning of meaning in its most basic form. Of course, I am glossing on the complexity of both primordial meaning and linguistic meaning. Linguistic meaning, though grounded by primordial meaning, takes on a life of its own once established in a population. This is why Heidegger made pains to distinguish between being-in-the-environment and being-in-a-linguistic-world, with the latter reserved for those humans who have learned a language and grown up in a social-linguistic community.