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The Conventional Source of De-Re Necessities, Sebastian Obrist (USi)

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This is a post by Sebastian Obrist (USi), a speaker from our Spring 2021 Seminar Series. If you would like to attend a seminar, please sign up using this link. You can also download the full schedule here.

“We must attempt to determine what grounds what; and it will be largely on this basis that we will be in a position to determine the viability of a realist or anti-realist stand on any given issue.” (Fine 2012, p. 42)1

The source of modality

Possibility and its dual notion necessity – in short modality – have throughout the history of philosophy been reliable guarantors of debate and puzzlement. According to Michael Dummett one of the most pertinent issues in this area concerns the source of modality2.

But what does it even mean to ask about the source of modality? As suggested by a rapidly growing tradition in contemporary metaphysics, source questions are questions about grounding. While grounding comes in different varieties the core notion is supposed to pick out an explanatory relation of a special kind. In contrast to the perhaps more familiar causal explanations chiefly figuring in scientific contexts, grounding is said to be distinctively metaphysical. As suggested by Kit Fine, one of the father figures of the very notion, grounding connects explanans and explanandum by some ‘constitutive form of determination‘ (2012, p. 37). For example the fact this table is brown and rectangular is grounded in the fact that it is brown and in the fact that it is rectangular.

Linguistically it is common to use the expression ‘x in virtue of y’ to indicate that x is grounded in y or to use the active form that y grounds x. Accordingly when concerned with the source of modality the question is the following: in virtue of what is something possible or necessary?

Approaching this question requires a brief introduction of the proper objects – the bearers – of modality. It has been suggested that the bearers of modality are the same sort of thing as the bearers of truth and falsity. The following is a case in point: just as we apply ‘it is true that’ or ‘it is false that’ to sentences so do we apply modal expressions like ‘it is possible that’ or ‘it is necessary that’ primarily to sentences.

The following examples and the fact that they (hopefully) all feel quite habitual illustrate this commonality between modality and truth:

  1. It is true that the sky is blue.

  2. It is false that the sky is blue.

  3. It is possible that the sky is blue.

  4. It is necessary that the sky is blue.

But crucially the analogy breaks when we are asking the source question. There are important differences between what counts as a satisfactory answer to questions about the source of truth and those concerned with the source of modality. Consider the following examples:

  1. In virtue of what is 1 true, respectively 2 false?

  2. In virtue of what is 3 possible, respectively 4 necessary?

While pointing out how things are or appear to us in the world, for instance that the sky is of (or appears as being of) a certain color intuitively might be enough to answer questions like 5, the same strategy is not satisfactory in the case of 6. Calling attention to the sky having (or appearing as if having) a certain color might settle whether it is possible that the sky is blue, but it won’t explain whether this is contingently or necessary the case. The world it seems is not enough to account for distinctions between what is possible and what is necessary and thus not sufficient for grounding modality.

A position which explicitly endorses this conviction is Modal Conventionalism. The position asserts that modality is at least partly grounded in our conventions. Note that the relevant notion of convention should be understood in a very wide sense; that is as a catch-phrase for all kinds of mind-based contributions. Thus accordingly modality is not exclusively explained by mind independent reality but at least partly by our contributions to this reality.

In the philosophical debate this anti-realist position has more recently lived a shadowy existence because of its supposed reliance on analyticity. Since the latter notion got into discredit as a result of various attacks3, Modal Conventionalism is often regarded as a non-starter. Thus the received view is that conventions play no role in grounding modality.

In contrast to this I believe that Modal Conventionalism is a serious contender and offers an interesting and innovative answer to the source question.

By focusing on what I call ordinary de re necessities – sentences like ‘Anna Tumarkin4 is necessarily human.’, I illustrate how conventions in the relevant sense play a role in explaining an important class of modal statements. What is crucial about this explanation is that there is no reliance on any notion of analyticity whatsoever.

The plausibility of this account then sheds new light onto the old debate between realist and anti-realist stand vis-à-vis modality. Given the centrality of modality to contemporary metaphysics allowing our conventions as plausible grounds of modality (or at least as partial grounds of de re necessities) is a spark to the blistering fire of anti-realist metaphysics.

About the Author

Sebastian Obrist is an MA student in Philosophy at the Università della Svizzera italiana (USi) in Lugano. His interests lie within the Philosophy of Language and its intersections with other fields, mostly Metaphysics and Philosophy of Science. Currently, he is working on his Master’s thesis which is about the kind of representation occurring in scientific modeling. You can contact Sebastian via email.


1. Fine, K. (2021) Guide to ground in Correia, F. and Schnieder B. (eds) Metaphysical Grounding. Cambridge: Cambridge University Press, pp. 37-80

2. Dummett, M. (1978). Truth and Other Eignmas. Cambridge: Harvard University Press, p.169

3. See for instance Quine, W. V. (1951) The Two Dogmas of Empiricism. The Philosophical Review Vol 60, No 1, pp. 20-43)

4. Anna Tumarkin (*1875 -†1951) was the first female professor in Europe (for philosophy and aesthetics) who was granted the right to examine doctoral students and aspiring professors.

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