Foreword
From The Journal of Philosophy, 111: 9/10 (special issue on Ontological Disagreement), 2014, pp. 449–454.

People disagree about all sorts of matters. Sometimes they disagree about how
things are, for example, about whether a certain wine is corked, or about whethera certain book is interesting, a thesis original, a type of act morally reprehensible.
Sometimes people disagree also about what things are. Is the duck-billed platypusa kind of mammal? Are viruses organisms? Is light a wave or a stream of particles? What is virtue? Indeed, sometimes people disagree even about whether certain things exist at all, about what there is (τὸ ὄν or τὰ ὄντα). That is, their disagreements may at bottom be ontological. For example, suppose some of us disagree about whether there is, or is not, orange juice in the refrigerator. This could
be represented (albeit somewhat pretentiously) as an ontological disagreement—
though here, only about a small and not especially exciting part of what there is,namely what there is in the refrigerator.
If we wish to settle or resolve our disagreement about the orange juice, we
will, barring very unusual circumstances indeed, surely not turn to philosophy.
We will rather simply walk over to the refrigerator, open the door, and lookwhether or not there is a carton, bottle, or pitcher of orange juice in it. Other cases
may in practice prove vastly more difficult to settle. Consider the issue of whether
there is life, or intelligent life, on other planets, in faraway galaxies. This is something about which people (can) clearly disagree. And here it may prove very difficult, even physically impossible, to go to those planets and “check” in order toresolve the disagreement. Nevertheless, we are inclined to think that checking is
the natural thing to do, is the right way of seeking to address and settle this question. Again, no help from philosophy is wanted or needed; in fact, it is unclear
what philosophy could contribute towards settling the matter.
There thus are disagreements which could be thought of as ontological disagreements and which call for empirical resolution. Other ontological disagreements—say, whether your phone number occurs in the decimal expansion of π—appear most immediately to call rather for mathematical or arithmetic methods fortheir resolution: if we had a proof to the effect that this is impossible, the question
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would be answered in the negative; if, on the other hand, we, at some stage of calculating the value of π, encountered your phone number in the decimal expansion,or if we had a proof that this would be, not only very likely, but bound to happen
if we carried our calculations far enough (beyond the fifteen trillion decimal digitsof π that have actually been calculated thus far), we would have answered thequestion affirmatively. Absent either having received such a result by calculation,or having a proof, the question is open, and is one about which it is possible todisagree. But, as with questions about what is in the refrigerator or about whether
there is life on planets in faraway galaxies, there seems to be no role for a distinctively philosophical contribution towards settling the question about the expansionof π. Similarly, there seems to be no distinctive role for a philosophical contribution towards settling ontological questions that appear to depend on administrative, legal, or political decisions. Whether there is, or ever was, such a thing as theKingdom of Tavolara is not an empirical question, or not exclusively an empiricalquestion. (Checking whether the island, Tavolara, exists might be a necessary step
towards, but is not sufficient for, arriving at an answer about the Kingdom.) Yet
neither does this seem to be an ontological question of the kind philosophers worry about. It is a matter that only politics, political historiography, or the institutions of international law can resolve, just as it is a matter of international law andpolitics whether the Grand Duchy of Flandrensis exists today, or is a matter oflegal stipulation and practice that there are such things as binding contracts, trust
funds, labor unions, or bicycle lanes on particular roads.
There are, however, also ontological questions that do seem plausibly to fallwithin the purview of philosophy, and about whose answers philosophers may(and do) variously disagree. Traditionally, these include “weighty” questions,which many people, including most non-philosophers, would take to be characteristically “philosophical” ones. Think of the three that Kant mentions: Does God
exist? Is the soul immortal (i.e., are there immortal souls)? Is our will free (i.e., isthere such a thing as a free will)? It is prima facie much clearer that philosophy
has a central role to play in thinking about these questions, not least because(some) philosophers have sought, and to this day seek, to clarify just what is being
asked in each case, and to reflect on what would count as settling these questions,or on whether they can be settled at all. Indeed, even if one holds that one or moreof these questions will, after having been suitably clarified, reformulated, or further divided into a number of sub-questions, call for an empirical answer, or empirical answers, it still seems that these are philosophical questions in a way inwhich questions about the contents of refrigerators, life on faraway planets, thedecimal expansion of π, or the Kingdom of Tavolara are not. They are philosophi2

cal questions precisely insofar as a large part of the difficulty in answering them,or in denying that they can be answered, lies in the sort of conceptual clarificationthat is required to determine what exactly needs to be settled (perhaps empirically) in order to answer them.
When it comes to disagreement about the answers to these philosophicalquestions, and to various others, there is one important aspect to which we want
here above all to draw attention. It typically seems to the advocates of each of the
opposed alternatives that the answer to the question—the resolution of the disagreement—matters a great deal. Thus the overwhelming majority of theists believe that it is a matter of utmost importance that God exists. (Epicurus might be
an interesting exception.) Atheists, for their part, typically think that it is an important fact about the world that there are no divinities. Indeed, for all their disagreements about what there is, both theists and atheists (except perhaps apatheists,such as Diderot) are agreed that whether or not God exists makes a difference.
Likewise, it seems to matter whether or not there is some form of personal immortality. And while the conclusion for which some philosophers argue, namely thatimmortality would actually be a bad thing for us (because of the “tedium of immortality”, or because “finitude” is necessary for our, human, lives to be “meaningful”), is perhaps surprising, such a conclusion is surely far less surprising thanwould be maintaining that immortality is irrelevant, that it makes no difference
whether or not we, or some important part of us, are, or is, immortal.
This feature of “making a difference” is of course not restricted to ontologicaldisagreements of the philosophical kind. Perhaps it does not matter very muchwhether there is orange juice in the refrigerator, or whether the decimal expansionof π does in fact contain your phone number. But surely the existence or nonexistence of life on faraway planets can make a big difference to our lives, at least
potentially. Perhaps few care about the Kingdom of Tavolara, beginning with thelast descendants of the family that proclaimed its existence, the happy owners of
the restaurant Da Tonino, Re di Tavolara on the island’s bay. But surely the existence or non-existence of the Kingdom would make a significant practical difference to those living on the island, e.g. concerning the taxes they owe, and towhom they should pay them. Surely, the existence or non-existence of a binding
contract will make a huge difference to the relevant parties. And, to take a rather
different kind of case, if some of us believe in ghosts and think that certain houses
are haunted, while others of us hold that there are neither ghosts nor haunted
houses, this almost certainly will bear on some of our decisions, say, decisions
about whether or not to buy, and to move into, a supposedly haunted house. Disagreements often matter—sometimes a great deal—and they do so in many spheres3

of life and in inquiries of many kinds, including of course in philosophical investigations. Disagreements about what there is are no exception.
Still, we want to draw attention to this feature of “making a difference” because one striking fact about certain ontological disagreements with which philosophers have engaged recently is that the “side” one takes does not seem tomake a difference; indeed, it seems to make no difference at all. For example,
those who deny that numbers are among what there is typically take pains to assure us that this denial is in no way meant to challenge or undermine ongoingarithmetical and mathematical practice. Indeed, they often assure us that their distinctively “philosophical” form of denying that there are numbers is to be distinguished sharply from “obviously insane” forms of denying that there are numbers—forms of denying this which would call for rejecting our arithmetical andmathematical practices as illegitimate. Similarly, those who deny that there areobjects such as tables and chairs, over and above some more fundamental “items”
arranged table-wise and chair-wise, do not typically deny that our more ordinary
ways of speaking, including speaking of tables and chairs, are acceptable, at leastin a way, or to some extent. Thus this kind of denial that there are tables andchairs, by contrast to an “obviously insane” kind of denial, looks, again, as if it
might well make no difference.
But not making any difference in these ways can easily give rise to any number of perplexing questions. Are those who say that numbers do not exist andthose who maintain that they do exist really disagreeing with one another? Arethey even disagreeing at all? If they are disagreeing, what exactly are they disagreeing about? (It is surely not helpful at this stage to insist that they are simply
disagreeing about whether or not numbers exist.) And if they are not disagreeing,or are not really disagreeing, how are we to understand the fact that they takethemselves to be disagreeing? Are the parties to such a putative disagreement justconfused? Or talking past each other? If it is a matter of confusion, what kind of
confusion is involved? If it is a matter of talking past each other, how does thiscome about? Are the relevant parties perhaps attaching different meanings to thestatements that give expression to their disagreements, or to specific locutions thatappear in those statements? If so, just what is each party saying?
Carnap and Quine famously provided important, influential discussions of issues relating to questions of this kind, and for some time their views seemed, tomany, to settle matters in one way or another. More recently, however, thosequestions and the “meta-ontological” disputes they lead to have again become theobject of vigorous inquiry and debate. Some contributors to the debate continue toengage with those earlier discussions. Others do not, or do not do so directly, but
4rather aim at redefining the very terms in which the discussion should be conducted. Yet together they all reflect a renewed interest in the philosophical dimensionof ontological disagreement. This issue of The Journal of Philosophy is devoted
entirely to work arising out of such renewed interest, and to its relevance to thebroader questions that define the aims and scope of ontology in contemporary
metaphysics.
Wolfgang Mann
Achille C. Varzi

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