It is generally assumed in philosophy that we have a great many existential beliefs. We believe that objects in the external world exist, that other people exist, that we ourselves exist, that mental states exist, that space and time exist, etc. Maybe not everyone believes that atoms and numbers exist (or moral values or gods), but the ordinary person has many existential beliefs, not always expressed perhaps yet lurking in the background. It is assumed that the ordinary speaker expresses existential beliefs all the time—whenever he or she refers to something. Thus Russell’s theory of descriptions asserts that anyone who uses a definite description is expressing an existential belief, and the same is true for proper names and demonstratives. Existential beliefs are assumed to be the most common kind of belief there is, ten a penny–the mind is crammed with them. Whenever I look around the world I am having existential beliefs about what I see: this exists, that exists, the thing over there exists, etc. I am constantly employing the concept of existence–not consciously perhaps, not explicitly, but unconsciously, implicitly. Right now I believe that this cup exists, along with the coffee in it. During my dreams I believe a great many existential propositions (which are largely false). We are all, in this sense, existentialists.
But is this really plausible? Isn’t it awfully intellectualist? Do animals go around equipped with existential beliefs unlimited (assuming they can have some beliefs)? Do young children confront the world with a barrage of existential beliefs? Do you really form an existential belief corresponding to every object you perceive (“That is red, and it also exists”)? Does every speaker have a belief corresponding to the first conjunct of Russell’s analysis? It is true that we sometimes have existential beliefs, which get expressed when questions of existence have been raised—say, about God or atoms or other minds or numbers—but do we have them as a routine matter whenever we interact with things? Isn’t this just far too much thinking? The OED defines “exist” as “have objective reality or being”: do we really wield this concept all the time? Do little children think, “This doll has objective reality or being” as they play with said doll? And what does “have objective reality” mean—doesn’t it mean “does not have purely subjective reality”? Is this what passes through the mind of the average boy or girl, or chimp or dog? You might reply that such callow creatures at least take an existential stance towards the world—that they are in some way “ontologically committed”. That is, their general attitude and behavior indicate that they take things to exist in some way (fear and avoidance will play a role). That seems reasonable enough, but it doesn’t imply belief—they act as if they have an existential belief without really having one. Sometimes people have a genuine existential belief and may even give voice to it by using the word “exists”, but generally they do not—they are merely behavioralexistentialists. This notion would need some explaining, but at least it enables us to avoid the overly intellectualist position outlined. It enables us to say that a creature can be ontologically committed to x without believing that xexists (that would suit Quine given his skepticism about belief in general). It also enables us to recognize the centrality of existence to living beings without supposing that they constantly have existence on their minds—it does matter to living beings whether a thing exists or not (food, predators, etc.).
The indicated position would then appear to be as follows: only in rare cases does the existential stance manifest itself in the form of existential belief, typically when a question of existence has been raised. So someone might have acted as if God exists for his entire life and only recently come to believe that God exists—for the question might never have occurred to him before. Similarly, people might behave as if the external world exists without ever believing it to exist (or individual things within it), and only come to believe in it when questioned on the subject. Suppose a person unreflectively goes about his business as if the world exists, never formulating a belief to that effect, and one day is confronted in the marketplace by a skeptic who makes him consider the question: he might affirm, “Yes, I do believe the external world exists”, having only just arrived at this belief. And let’s not say he implicitly believed it all along, because that would be nothing but a misleading expression of his behavioral stance (do children and animals have such implicit beliefs?). You need not believe something, explicitly or implicitly, in order to act as if it is true. The right thing to say is that philosophy can make you form existential beliefs you didn’t have before. Isn’t this a more realistic picture of our dealings with existence? Existence is certainly in our blood as living creatures, but it is not thereby in our beliefs.
This has a bearing on three philosophical issues: skepticism, realism, and reference. The skeptic cannot claim that our existential beliefs about the external world, other minds, etc. are unjustified, since we have no such beliefs in the normal course of things—the question has not arisen for us. Of course, he may rephrase his skepticism to question our existential stance, but it is not clear that stances are the proper objects of justification; so here is a possible route to blunting the force of skepticism—it is not denying anything we believed before the skeptic came along. We might respond, “I have no beliefs to that effect, so I am not troubled about their lack of justification”; and we could decline to form the beliefs the skeptic imputes to us. We never claimed to have justified beliefs about the existence of external things. This would explain why skepticism seems so irrelevant to the ordinary person: he or she never attempted to justify existential beliefs of the kind the skeptic is casting into doubt, having none. We were never in the belief justification business to start with; we were just living our lives in an existentially sensitive way (we had an existence-sensitive “form of life”).
In the case of realism it need not be assumed that existential beliefs form the evidence for the realist thesis: a moral realist, say, need not assert that people have beliefs to the effect that moral values have objective reality—people are not moral realists in that sense. The question is rather whether their moral practice reflects a commitment to realism—whether they take a realist stance. Ordinary people are not moral realists or moral anti-realists if that implies certain sorts of existential beliefs, so there is no point in inquiring what beliefs they have on the subject; instead, we must look to their practices (Wittgenstein would approve). Nor do people believe that the existence of material objects is independent of sensory appearances, or disbelieve this; at most they act and talk in ways that may be interpreted along those lines. So there is no point in asking whether commonsense belief is realist or anti-realist about some given subject matter; there isn’t any such belief. Similarly for mathematical realism: people don’t generally have any beliefs as to the objective existence of numbers, though their actions may be more consistent with one position than another. This makes it harder to pin an ontological commitment on them in the absence of any belief on the matter. It is relatively easy to tell whether someone is a divine realist (or a ghost realist) since here people do have genuine existential beliefs—you can just ask them what they believe. But if they have no such beliefs they need to interpret their practice just as an outsider must. Generally, if you ask someone whether he believes that numbers exist or moral values or fictional characters, you will not get a straightforward answer, for the simple reason that he has never formed a belief on the question (unless he happens to be a philosopher). People only form existential beliefs of this kind when they are called upon to do so—and they may not be so called upon. Otherwise they tend to fumble.
In the case of reference we can junk the idea that speakers harbor existential beliefs with respect to their objects of reference (except in special cases). A user of a definite description or a proper name does not typically believe that his reference exists (though he doesn’t disbelieve it either). Child speakers are not brimming with existential beliefs to this effect—the question has not entered their little heads. Maybe we can say that they act as if their reference exists, but that falls short of actual belief. It is just not the case that a speaker thinks every time she refers, “My reference has objective reality” or “My reference has more than merely subjective reality”. She might not even have the concept of existence at all. Existential belief is a genuine mental state, to be sure, but its natural home is in certain special situations in which existence is questioned or debatable; as philosophers promiscuously use the notion it is a philosopher’s invention, vastly overgeneralized. If you look into the speaker’s head you will not find existential beliefs skulking there, unless they happen to be there for special reasons (references to God will typically involve existential beliefs, pro or con).
The philosopher is much concerned with the formation of existential beliefs—that may be thought to be his primary occupation (ontology)—but the ordinary person is not likewise obsessed. He or she does not resort to the concept of existence very often and only when pressed. We may grant on reflection that everything that is exists, but we don’t normally bother to form existential beliefs about the world. The concept, after all, is puzzling and problematic—philosophers and logicians cannot decide on its correct analysis—and people generally steer clear of it.
 I don’t at all mean to endorse any kind of behaviorism here, merely to gesture at the whole range of actions and attitudes a living being brings to the world, no doubt involving emotion and desire as well as tendencies to act in certain ways.
 It is noteworthy that we don’t need to use the word “exists” in order to single out certain sorts of cases that don’t imply existence: we say that we were under an illusion or were hallucinating or dreaming or that Sherlock Holmes is a fictional character or that there are no such things as fairies. Seldom do we invoke the somewhat stilted word “exists”: it is philosophers who describe all these cases as failures of existence. Explicitly existential belief is an unusual state of mind, reserved for special occasions. Philosophers are in it a lot, the folk not so much.