The Epistemology of Modality: Setting Up the Question for Classical Indian Philosophy–A Guest Post by Anand Vaidya

Hi All,

Matthew and Elisa asked me to provide a guest post on a project I am working on. I just spent the last two weeks in Europe, first Belgrade, Serbia and then Aarhus, Denmark working on one of my main areas of research, the epistemology of modality. What has struck me the most over the 15 years I have worked on the topic is how little attention is given to this topic in comparative philosophy. But maybe I just don’t know enough. So, I am looking for help. To understand what I am exploring read 1-3 below. If you are further interested in the issue and want to see where I am coming from look at 4-6. Any help would be appreciated. I plan to write a major article on this topic.

 1. The Core Questions in the Epistemology of Modality

The epistemology of modality is primarily concerned with the following questions:

Modal Sorting: how do we come to know what is possible, necessary, and essential for a given entity or kind of entity?

Modal Mechanism: what single mechanism or set of mechanisms provides us with justification for believing that a proposition either is possible, necessary or essential?

Modal Skepticism: what is the extent of human modal knowledge? Is it limited to ordinary possibilities, such as the possibility that a cup located at one place can be located elsewhere, or are extraordinary possibilities, such as the possibility of disembodied consciousness, also accessible with justification?

Modal Architecture: in the range of the possible, the necessary, and the essential, is one more basic than the others, such that it provides the basis for knowledge of the others. For example, is necessity more basic than possibility, such that we first come to know about necessity, and then derive possibility form it?

2. The Comparative Questions for Classical Indian Philosophy

What does classical Indian philosophy have to say about the epistemology of modality? Here are the basic questions:

Identification of Texts and Philosophers: Which Texts and Which Philosophers addressed the epistemology of modality?

Comparative Question: How do classical Indian philosophical views about the epistemology of modality relate to Western philosophical views?

Centrality: If classical Indian philosophy does not engage the epistemology of modality as seriously as Western philosophy does, what is the best explanation for that? If it does engage it, what is the centrality of it to classical Indian philosophy?

Indirect Answer: If classical Indian philosophy does not engage the epistemology of modality directly, is there an answer to another question that does provide an answer to questions in the epistemology of modality? That is not a general question about knowledge or perception, but something more specific about how we access necessity and mere possibility.

3. My Current Thoughts

 My current thoughts are the following:

  1. Classical Indian philosophy has an indirect answer the central questions in the epistemology of modality because it is not a central topic in the classical Indian philosophy because modal arguments are not a central part of the Indian philosophy.
  1. The indirect answer will come from classical Indian debates on observation of co-presence and co-absence in inference. This makes classical Indian philosophy a solid contributor to the current turn toward modal empiricism and a rather strong opponent to the rationalism of the past 20 years.
  1. There is an interesting and important story about why classical Indian philosophy does not engage this question, and it sheds light on an important difference between how classical Indian philosophy conceives of itself relative to Western philosophy.

But the real question is: For those in the know, since I know so little, where can I go to get more information? And what are the answers to the questions I have raised?

4. The Recent History in Western Philosophy

In the past 20 years (1994 to 2014) the dominant program in analytic epistemology and philosophy of mind has focused on rationalism, the attempt to explain modal knowledge in terms of a priority. The strongest proponents of this view are David Chalmers, George Bealer, Christopher Peacocke, and Laurence Bonjour. However, there has been a growing number of philosophers, such as Timothy Williamson and Bob Hale, that have pushed for a mixed view on which some of our modal knowledge is a priori, some a posteriori, and some neither a priori nor a posteriori. And some philosophers, such as Otavio Bueno and Sonia Roca-Royes have pushed further for a form of modal empiricism where our knowledge of possibility is either derived from similarity judgments or modality is fundamental and not to be explained in terms of something more basic, such as possible worlds.

5. The Main Theories in Western Philosophy


We derive knowledge of possibility from conceiving of various states of affairs.

Counterfactual Imagination

We derive knowledge of possibility from counterfactually imagining what would happen if certain actual facts were not the case.

Essentialist Deduction

We derive knowledge of possibility from first considering the essential natures of the relevant entities under consideration.


We come to know that something is possible through direct intuition of possibility.

Free Variation

We can come to know the essences of an entity through free variation in imagination where we abstract away from particular properties of an entity until we come to arrive at a model or an invariant of the entity. The invariant gives us the essence, whereby we then deduce what is possible for the entity.


We come to know that it is possible for x to be F because x is similar to y, and we have observed that y is F.

6. The Centrality to Western Philosophy

The debate over the epistemology of modality is at the heart of Western philosophy, both Analytic and Non-Analytic, both classical and contemporary.

Consider the following classical cases:

St. Anslem argued for the existence of God on the basis of the inconceivability of God’s non-existence because the definition of God included existence as an essential property.

Rene Descartes argued for the separation of mind and body on the basis of the conceivability of his mind existing independently of his body because the definition of mind is that it is essentially thinking while that of body is that it is essentially extended.

George Berkeley argued for idealism, understood as the claim that to exist is to be perceived, based on the inconceivability of an entity existing while being perceived by no one.

Edmund Husserl held that the essences of entities could be arrived at through free variation in imagination and that essentialist knowledge was central to a phenomenological philosophy.


About Matthew Dasti

Matthew R. Dasti is Associate Professor of Philosophy at Bridgewater State University.

21 Replies to “The Epistemology of Modality: Setting Up the Question for Classical Indian Philosophy–A Guest Post by Anand Vaidya”

  1. Thanks, Anand, for this very interesting post. My first reaction is that the distinction between two types of non-existing entities, which Elisa discussed in a post some time back, might be relevant because it seems to index an a priori and a posteriori kind of impossibility. There are things like a barren woman’s son which are conceptually impossible, and then there are things like sky-flowers and hare’s horns that are absolutely nonexistent but not conceptually impossible.

  2. Have a look at B.S.B. II.ii.28. There Sankara is rejecting the Idealist Buddhist notion of impossibility in relation to the ‘external object’. The ‘external object’ never enters the realm of acquaintance and becomes a possible object – therefore it is is impossible. As I understand it, this notion of impossibility can’t be called a priori because that would assume that you can arrive at facts of some sort. It might be termed a stipulative definition.

    Sankara holds that ‘what is, is possible’, in other words if the valid means of knowledge can be applied to it, it is possible. Worth reading.

  3. Thanks so much for this, Anand. My sense is that your conjecture 3.2 is in the right place: a good place to start to look for indirect answers is in accounts of how we come to grasp the tie between inferential relata. A good place to get a sense of this from the mature Nyaya perspective is Kisor Kumar Chakrabarti’s *Classical Indian Theory of Induction* ( . Nyaya advances what looks like an odd view that we somehow grasp this relationship by a kind of non-standard perception. Chakrabarti provides a great treatment of this theory and embeds it in a rich dialectical context in Indian thought.

    To bolster your point about the “indirect” approach I will also add that scholars of Indian thought with a strong analytic background are often of the opinion that that Indian theorists were “innocent of the notion of necessity” (a phrase by Siderits about Nyaya in his “Nyaya Realism, Buddhist Critique”), when necessity is thought of as a conceptual truth. I am sure that there are some who would push back against this (and I hope they speak up here), but this is not an uncommon reflection.

  4. Hi Matthew,

    This is really on point. I already started a draft of the paper some months ago. And the main part of the paper I wrote about was from Chakrabarti’s book on induction. I have a whole theory laid out based on his treatment of Nyāyā. I will look at the Siderits. Thanks for letting me post this research request up.

  5. Thanks for this interesting post. Apart from the points already raised (I agree with Andrew on the suggestion to look at discussions about the ontological status of absence), I would add:
    —the opposition between Nyaya and Mimamsa on one side and Buddhist Pramanavada on the other. The latter assumes that the world obeys rational laws (e.g., of non contradiction, so that perception cannot seize at once a particular and an universal) whereas the former, and especially Mimamsa, embrace empiricism: the world is for Mimamsakas the way it is, and philosophy will need to find new theories to explain it, if something unpredicted occurs (and, yes, perception can seize universals).
    —the insistence of Mimamsa authors (especially of the Prabhakara Mimamsa school) on the distinction of fields of application between perception and linguistic communication. Through the former, one seizes present states of affairs, whereas the latter, in the form of the Vedas, conveys for us knowledge of what *ought* to be. The domain of what ought to be is neither identical with nor reducible to that of state of affairs, according to Prabhakara Mimamsakas.
    —this fundamental opposition between two distinct realms is present also in other schools, even in the ones who deny the authority of the Veda. For Buddhist Pramanavada, for instance, instead of the Veda as a guide for what ought to be done one finds the Buddha’s teachings, which are founded on his intellectual intuition (yogipratyaksa). The latter is the capacity to intellectually grasp, without the need of mediations, the content of the Four Noble Truths (which pertain, again, to the domain of the ought and not of the is).

    A much more general question is: When did the problem of modality start to be conceived *as such* in Western philosophy and what prompted this development? Descartes and Anselm are great examples, but would have probably not described their work as related to the epistemology of modality, would they? Your impression that modality is less central in Indian philosophy might have just to do with the fact that no scholar of Indian philosophy has interpreted it in this way:-)

  6. Hi Elisa,

    Thanks for the comments. I will look into the aspects of classical Indian philosophy that you mention. I am very appreciative of any direction on this issue. As for your general question, I have a small comment on that one.

    It looks to me as if one could argue that St. Anselm had no interest in the epistemology of modality. Some would even argue that he simply used the term ‘inconceivable’ to mean ‘logically impossible’ and as a consequence was not interested in how the mental operation of conceiving might relate to what is objectively possible or impossible. However, with Descartes and with Hume and Kant I think it is much harder to make the claim that they did not see themselves as interested in the primary questions in the epistemology of modality. Descartes, Arnauld, Spinoza, Leibniz, Hume, Berkeley, Reid, and Mill all discuss a conceivability to possibility thesis, its role in metaphysics, and whether or not it is reliable. Many even suggest deep points that make it the case that the 20th century debate, at least in my opinion, has not gone beyond what they say.

    Thanks again 🙂

  7. This sounds like a really interesting project. Good luck!

    Here are two things that occur to me about the indirect approach.

    One, there are lots of conceptual arguments to the effect that some alleged entity or state of affairs is impossible. For instance, the section of Vasubandhu’s Viṃśikā on atomism (verses 11-15) contains arguments against the possibility of atoms existing or at least against the possibility that we can coherently conceive of them. One big reason people interpret Vasubandhu as a metaphysical idealist is that his argument here looks something like Berkeley’s “master argument” against the conceivability of mind-independent objects. Whether Vasubandhu intends those arguments to establish idealism or not (I say not, but that’s beside the point here), Vasubandhu seems to be working with some notion of modality.

    Second, in Sanskrit the gerundive (future passive) participle sometimes seems to have some variety of modality built into it. For instance, dṛṣya can be translated as “visible” and ramaṇīya as “enjoyable.” Maybe this is reading too much into translation practices, but I wouldn’t be surprised if a Grammarian or other philosopher had something to say about gerundives that might border on talk of modality.

    • Ethan,

      you are more right than you claim, I think. A kṛtya is an *optative* passive participle, not a future one (although a Bhāṭṭa might claim that a kārya meets its condition for being realised in the future). Consequently, it means “what can be…” or “what must be…” (e.g. seen, done, enjoyed, meant).

      • Elisa,

        What do you think about the kinds of things that are said in debate or in dialogue to mark something as unfit? Consider terms like “anupapatti”. They suggest that some position or some entailment from a position is out of bounds such that we can dismiss it. Perhaps not unlike the claim in English “Such is not possible.”

        Do you think we can read modal force into these terms which suggest that something is “out of bounds” so to speak?

        • Elisa, I was also thinking of the optative in Sanskrit as a possible grammatical location for notions of modality. Thanks!

          Matthew, I agree that “anupapatti” has the sense of saying something is not possible (I sometimes even translate that as “is not possible.”). Also consider the idea that something is not established (“na sidhyati”), especially as the result of a prasaṅga argument that appeals to a logical contradiction as an unwanted consequence. If these sorts of prasaṅga arguments aren’t appealing to some notion of modality (at least the opponent’s notion of modality), I would be very surprised.

  8. Hi Ethan, Elisa, and Matthew

    Interesting grammatical points. I am not familiar with all of them, but I have put them on my list of things I must become familiar with soon. Let me separate out a number of questions, and then close with another more general issue.

    (i) Do classical Indian grammarians and philosophers acknowledge the difference between alethic (pertaining to truth) and epistemic (pertaining to knowledge) modality?

    (ii) Do classical Indian philosopher’s generally distinguish between de re and de dicto modality? Such as in the difference between ‘9 is such that it is necessarily greater than 7’ and ‘necessarily 9 is greater than 7’. In the former we have modality de re, predicated of an object, and in the latter we have modality de dicto, pertaining to a statement.

    (iii) Metaphysically there are at least two traditions of understanding alethic modality. One is a world based notion. To say something is possible is to say that it is true at some world. Another is a temporal notion. To say something is possible is to say that it is true at some time. That is some philosophers understand alethic modality to be about time others understand it to be about worlds. I think that there is some preference in Indian philosophy for some version of the temporal account. But I am not certain about this.

    (iv) I have recently come to the conclusion that there maybe room to generate a view based on comparison. I know that some schools of classical Indian philosophy included comparison as way of coming to know. Conceptually there is also a technique for arguing that comparison is a route to knowledge of possibility. So, I am curious if anyone knows of any passages where modality and comparison are discussed together?

    (v) Ethan, on the suggestion from V’s conceivability argument. I think you are right to suggest that there are conceivability arguments running through areas of classical Indian philosophy. It would be interesting if there are also passages where one finds elaboration on the ideas. Places where we find for example an explanation of how or why it works?

    (vi) Finally, I want to make it clear that my concern is really about the epistemology of modality, and not so much about semantics and metaphysics. I know that the three are related. Typically the semantics / syntax of a language and the metaphysics one adopts paints a picture for the epistemology. But I really want to find some areas where the discussion focuses on how we come to know what is possible or necessary.

    Thanks again for the tips and points. I will start reading about the grammatical issues soon.

    • Anand, your last set of questions points to a general methodological problem, namely, that of the cultural specificity of questions. I know that analytic philosophy aims at being universal (although it is often self-confined to the intuitions of English-speaking philosophers;-)), but I am not completely sure that it makes sense to look at a certain philosophical school and look for the answers to one’s own questions. I think it is much more interesting to have also one’s questions reframed. For instance, the opposition siddha vs. sādhya has a clear element of modality (the sādhya pertains to something which ought to be and the ought —kārya— never coincides with what is, neither temporally nor in a possible world), but it is not directly equivalent to the oppositions you discuss, does it?

      • I see no harm in Anand’s methodology at all. I think he’s been pretty careful not to project anything. He has a set of interests and he is wondering what the Indian philosophers say to it. You are right that, as Mohanty and others have reminded us, the classical Indian thinkers also had their own set of questions, and learning them is often as or more informative. It’s a good reminder. But I do think it makes perfect sense to engage in these sorts of comparative questions starting from one’s own interests if, like Anand, one is sensitive to the dangers of projection. Perhaps the conclusion , or part of the conclusion, is that they had different questions. But one gets there by probing things from one’s own set of interests and capabilities.

  9. Hi Matthew and Elisa,

    Thanks for both of your comments. I had not thought of what you are pointing out Elisa. I was thinking more in the way that Matthew describes: There is this problem in classical and contemporary western philosophy, did classical Indian philosophers say anything directly about it or could they have answered it indirectly?

    However, now that you have pointed out this insight about how they were thinking about certain components of time and modality, I am now additionally interested in a revisionary / reframed question. In light of how classical Indian philosophers thought about certain issues of time and modality in relation to actuality, what approaches did they take that western philosophers might learn from?

    I think that you are right to point out that I might need to adjust my question so that I can gain something valuable. So, in this way I see a compromise between what you are saying and what Matthew is saying. The compromise is the following. Don’t just take a question from one culture and assume that another culture will address it directly or at all. Rather, start with the question and then see what in the area might be relevant to it, and then reframe it if necessary. Your general methodological point sounds good. Of course in some cases there is no need to reframe, since the same question, and even for the same reason, maybe in play. But in this case, the case of modality, you could be correct. The general idea is that one may not want to discount a whole tradition of philosophy simply because they don’t explicitly address a question asked by another culture. Rather, there maybe a good reason why or a set of issues that explains why the question is different or not present.

    Also, in general, I am really excited by the idea that since some schools of classical Indian philosophy treat comparison as a pramāṇa we may learn something important about how to use comparison as a guide to knowledge of possibility from Indian philosophy. Recently, a lot of work is being done on how the correct way to generally think about knowledge of possibility comes from reasoning about similarity and comparison. However, to my knowledge no school of western philosophy has ever treated similarity or comparison as a unique method for gaining knowledge. Yet this is common in classical Indian philosophy. And it may turn out that in general, there is an important reason why: it is the primary route to knowledge of the possible that is unrealized. Now even if classical Indian philosophers did not make the connection explicitly between reasoning about similarity and comparison as a guide to knowledge of unrealized possibilities, it is interesting to see where they did take it and how that can be connected to the general idea.

    Again thanks to both of you for your immense help. I realize I am new to this, so if I am stumbling a bit Elisa, thanks for pushing me along to a more informed place.

  10. Anand, I just read something today that I’m putting up here. I admit that I haven’t put much thought into it, but it may be a lead.

    In short: knowledge of absences may be another relevant place to look. I’m most familiar with Nyaya, for whom absence (abhAva) is not an independent source of knowledge, but rather reducible to a kind of inference or perception. But it is still a way of knowing. In any case, in the classic example, imagine a bunch of clothes that are drying in the wind. Some have a mark which indicates that they are not to be brought in yet. Others don’t have that mark and should be brought in. Vatsyayana says that the absence of a mark is something that provides knowledge “these should be brought in”. As such, it is a mode of knowing, a pramANa.

    The opponent says that it’s wrong to say that there is an absence on the unmarked clothes, as an absence only occurs when something existing in reality is removed. So there can only be an absence if a mark is erased. (We can see this is a pretty crude notion of absence.)

    Vatsyayana responds that absence may be known by someone who, aware of the mark, does not see it in a certain place. This alone, underwritten merely by an individual’s awareness of the possibility of something, and it’s absence somewhere, provides knowledge of absence. (The relevant section is Nyayabhashya 2.2.8-12; I filled it out, but just a little). All one needs is a conception of the mark in question, coupled with awareness that it isn’t somewhere, and combining these, we have knowledge of absence.

    These remarks are consistent with his statement in the introduction to the Nyayasutras that pramANas provide us with knowledge of absences just as they provide us with positive knowledge. Seeing the room, I know there is no elephant there. My perception of the room *coupled with reasoning like “Were there an elephant, I’d see it”* is enough to give us knowledge of absences.

    What struck me re: your concerns is the way that Vatsyayana makes it clear that absence is something we discover according to our own recognition of possibility, and not something as crude as something existing being destroyed. A mark *could have been here*, but it’s not, so it’s absent. We inwardly scan the possibility of a presence, and then recognize that it isn’t here. Thus, we know of an absence.

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