Abstract
The Diamond Sutra is one of the earliest and most treasured of the Perfection of Wisdom Sutras and had a wide influence on the development of Zen Buddhism. There has been, in recent years, great interest in one particular form of sentences that repeatedly occur in the sutra, sentences of the form “A is not A, therefore it is A”. These sentences display what has been called the “logic of not” or the “logic of affirmation-in-negation”. They are of special interest since they do not only encapsulate one of the central insights of Zen Buddhism, that of nonduality, but at the same time seem to go against one of the most orthodox laws of logic in Western philosophy, the law of identity. This paper discusses the interpretation of these “diamond sentences” by the Vietnamese Zen monk Thich Nhat Hanh. I present Thich Nhat Hanh’s interpretation of the diamond sentences in terms of interbeing and go on to argue that and explain how, on his interpretation, the validity of the law of identity is indeed rejected. Finally, I spell out consequences for formulating a “logic of Zen” and for a related debate about the validity of the law of non-contradiction in Zen.
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Notes
Sentences that are instances of this schema also go against the law of non-contradiction. I get back to this in §4.
See, e.g., Noonan & Curtis, 2022 on qualitative and numerical identity.
In Kleene logic, e.g., there is a third truth value, neither true nor false, on which it also operates.
At some points, it sounds as if he proposes that there are two semantic senses of the negation, while at other points, it sounds as if he proposes only that there are two functions of the act of negation. In any case, it seems that one cannot simply assume that the negation works in the standard way.
Some diamond sentences contain the words “essentially” or “in essence”. There is at least a possible interpretation on which this goes against the idea that they are instances of the diamond schema. Thus, one could take the form of the first parts of the diamond sentences to be “A is not essentially A” or “A is not in essence A”, and one could take them to be compatible with the claim that “A is A”. It could be that A is A but only not essentially, or in essence, A. Thus, one might think that Aristotle is the student of Plato but not essentially the student of Plato or that Goliath is Lumpl but not essentially Lumpl. There can of course only be true examples of this kind if x and y can share identity without sharing essence.
He translated and wrote commentaries on various sutras, including for instance also the Heart Sutra, another central sutra for Zen Buddhism (see Thich, 1988).
He sometimes drops “be called” and specifies the form of the diamond sentences e.g. as “‘A is not A’, and that is why it can truly be A” (Thich 2021, 23).
The idea of interbeing is a substantial metaphysical claim, and a controversial one, at least from the point of view of Western philosophy. On this view, which may be classified as metaphysical coherentism, there are no fundamental entities, entities that do not depend for their existence on anything else, while on the standard view in Western metaphysics, metaphysical foundationalism, there are.
Plato thought that there are natural divisions in the world and that good theories “carve nature at its joints” (Plato, Phaedrus 265e). Thich Nhat Hanh does not believe in such divisions and does not think that we can “carve nature at its joints.”.
Thich Nhat Hanh seems to think of concepts as mental representations rather than as Fregean senses e.g., since such abstract objects are problematic in Buddhism due to issues regarding permanence and causality (see, e.g., Margolis & Laurence, 2023 on concepts).
He describes this more decisively in Zen Keys, writing that there is an “enormous chasm that opens between things and the concepts we have of them” and that “things are dynamic and living, while our concepts of them are static and poor” (Thich 1974, 36).
See also Thich 1974, 106.
Maybe “not” is part of the meta-language since the law of identity is part of the meta-language and maybe it is an “external negation”, as explained in Garfield and Priest, 2009, one that can be used to negate that A holds without thereby implicating that something else, such as non-A, holds. Yet, as Thich Nhat Hanh does not highlight the negation, it seems that, apart from this, he does not take it to work in a special way.
The use of “essentially” and “in essence” in some diamond sentences can also be interpreted so as to not be going in the way of the denial of the validity of the law of identity either but rather only so as to point to the correct interpretation of the diamond sentences. Thus, their function only seems to be to indicate that A does not have an essence, as one might think if one thinks that A has a separate self-existence.
Geach (1973) held at least a controversial view on identity, arguing that the notion of absolute identity has no application and that there is only relative identity.
The logic Suzuki has in mind is not a formal logic such as classical logic but maybe method in Zen such as koan practice. Yet, if it is fine to describe Zen using natural language (and that is of course a question), it should also be fine to describe Zen using a formal language, since a formal language is just a translation of a natural language. The issue the diamond sentences raise concerns a mismatch between our concepts and reality and that mismatch is or is not there no matter if we use words or formulas to describe reality.
See Noonan & Curtis 2022, §2.
Nagatomo himself argues that the diamond sentences are only contradictory as long as one understands them in light of Aristotelian logic, which assumes a “dualistic standpoint”, but that a proper understanding requires a “perspectival shift” to a nondualistic standpoint (Nagatomo 2000, 213).
This is not to say that the law of non-contradiction would hold in a logic of Zen, only that the diamond sentences do not show that it would not hold.
He quotes this passage frequently and sometimes adds “really” in the end, as in “And, after practicing, I saw that the moutains were really mountains and the rivers were really rivers” (Thich 2021, 23).
D. T. Suzuki makes a similar connection between the diamond sentences and the mountain passage (see Suzuki 2011, 216).
See also Thich 1974, §4 for a detailed interpretation of the mountain passage.
I would like to thank the audience at a talk at the Tokyo Forum for Analytic Philosophy (TFAP) for a great discussion and many insightful comments. I would also like to thank two anonymous referees.
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Dr. Mirja Annalena Holst is temporarily unaffiliated and was previously an assistant professor of philosophy at the American University in Vietnam.
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Holst, M.A. Swords and diamonds—Thich Nhat Hanh on the law of identity. AJPH 2, 78 (2023). https://doi.org/10.1007/s44204-023-00130-x
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DOI: https://doi.org/10.1007/s44204-023-00130-x