The jury, convened on October 11, 2025, selected Asst. Prof. Ezgi Iraz Su (Sinop University) from three submissions to award the Teo Grünberg Prize for Research in Logic to her article titled “Splitting Property for Epistemic Equilibrium Logics”.
Asst. Prof. Üyesi Ezgi Iraz Su (Sinop University) Title: Splitting Property for Epistemic Equilibrium Logics Abstract: Answer-set programming (ASP) is a declarative logic programming paradigm that provides an efficient problem-solving approach in logic-based artificial intelligence (AI). In ASP, problems are represented as logic programs, and solutions are identified through their answer sets. Equilibrium logic (EL) is a general-purpose nonmonotonic reasoning formalism based on a monotonic logic called here-and-there logic (HT). HT is a three-valued intermediate logic that lies strictly between intuitionistic logic and classical logic. EL was originally proposed by Pearce as a foundational framework of ASP, where answer sets of an ASP program are captured by the equilibrium models of the corresponding HT theory. While ASP has proven successful as a knowledge-representation formalism, it encounters specific situations where its language falls short of accurately representing and reasoning about incomplete information. Researchers now widely agree that ASP requires powerful introspective reasoning with the use of epistemic modal operators. Therefore, epistemic specifications (ES) have been proposed as extensions of ASP programs with subjective literals. These new modal constructs in the ASP language make it possible to check whether a regular literal of ASP is true in every (or some) answer set of a logic program, which is required to model incomplete information in ASP. Thus, ES programs are interpreted by world-view structures, which are essentially collections of answer sets (or equilibrium models). However, despite long-lasting debates on how to capture the intended meaning of ES programs via world views, researchers have not reached a consensus on fully satisfactory semantics. Recently, Cabalar et al. have argued that such research on ES semantics should be grounded in formal robustness rather than in test examples. Thus, inspired by ASP’s foundational properties, they introduced a new structural principle called the epistemic splitting property (E-SP) and designated it as one of the compulsory criteria for epistemic ASP. However, this criterion has left several intuitive semantic approaches unsatisfactory. This paper generalises Cabalar et al.’s approach to a more comprehensive, meticulous, and conservative extension of ASP’s original splitting property, thereby broadening the applicability and enhancing the efficiency of epistemic splitting property for general epistemic equilibrium logics.
Jury Members (Alphabetical by surname):
Prof. Dr. Ahmet Ayhan Çitil (İstanbul 29 Mayıs University)
Prof. Dr. H. Bülent Gözkân (Mimar Sinan Fine Arts University)
Prof. Dr. David Grünberg (Middle East Techical University)
Prof. Dr. Özgüç Güven (Istanbul University)
Prof. Dr. M. Nazlı İnönü (Istanbul University)
Prof. Dr. Halit Oğuztüzün (Middle East Techical University)
Grateful that it has been developed as an academic discipline.
Logic has offered humanity countless insights and continues to do so.
On World Logic Day, let us remember what we owe to logic and try to enumerate, as best we can, what it has offered us so far and what we can expect from it in the future.
We know that logic emerged in Western thought as an answer to the question “Can we know what we do not know?”. Logic was thought to be the means of lifting the veil of what we implicitly know.
It paved the way to separate sophism from philosophy. The principle of non-contradiction offered a very effective and important criticism against those who thought that every thought was equally existent and defensible.
The idea that objects discussed by language must possess one of a pair of contradictory predicates expanded the horizon of scientific inquiry. With the principle of non-contradiction as its background, the sciences were developed on the basis of making judgments and inferences about objects that were thought to be fully determined.
The absolute possibility constituted by the aforementioned pairs of contradictory predicates was accepted by some as the real existence, and this tendency paved the way for classical metaphysics.
The idea that the universe is finite and closed is based on the idea that the number of fully determined objects cannot be indefinite; while the idea of the universe being boundless and open was grounded in the infinity of the absolute possibility mentioned earlier, suggesting that the universe could not be finite.
The difficulty, and even impossibility, of confirming the truth of a proposition with content drove humanity to seek refuge in formal validity and to develop its body of knowledge based on logic. Starting with what we can agree upon, logic has filled the sails of researchers as they embark on paths toward new truths.
Scientific or demonstrative knowledge has been defined as knowledge obtained through valid reasoning from premises accepted as true, one way or another.
In the modern era, the emphasis on knowledge has shifted to thinkability or expressibility. Mathematics has transformed into a vast discipline where logical principles and laws are used to examine what can be said about objects defined through postulates. It has been thought that some of the objects studied through logic-based mathematics can, under certain interpretations, explain facts and phenomena. This has led to a significant explosion and enrichment in the activity of developing scientific theories.
On the other hand, since the justification of a theory containing complex laws, definitions and principles requires the derivation of an observation proposition from the theory, logic has never lost the leading role in the verification of scientific theories.
Whenever logic was not used properly and sufficiently as a tool, injustice, power relations and ultimately corruption prevailed.
Now, let’s consider today…
As a tool, logic, especially through the work of mathematicians, is being developed within both classical and non-classical frameworks. The diversity has grown so much that the literature now includes numerous studies on debates about logical monism versus pluralism.
Logic, through the development of formal systems, stands at the heart of unprecedented technological advancements in history, made possible by computational theory.
Although Immanuel Kant and his followers’—largely justified—criticisms led to logic temporarily diverging from its canonical usage, the intellectual return of metaphysics through different channels has ushered logic into a new era. Many philosophers are devoting significant effort to observing reality through the results achieved in logic. What was once contemplated through classical logic is now being re-examined from the perspective of modern logic. To the extent that humanity realizes its limits in thought, it is seriously interested not in the question “”What kind of reality does language and its logic present to us?”.
Meanwhile, many questions resisting scientific and philosophical investigation continue to occupy our minds. How life emerged in the physical universe, the nature of consciousness and mental states, and how quantum and classical physics might be reconciled are examples of questions that await entirely new breakthroughs in human thought—and perhaps the development of entirely new logics.
What logic has offered us so far is perhaps only a fraction of what is possible.
The logic of language was fortunately realized or fortunately invented…
Logic has fortunately been developed through the efforts of many thinkers…
What would humanity be like if it did not exist and did not evolve into what it is today?
Happy World Logic Day!
Prof. Dr. Ahmet Ayhan Çitil 14 January 2025
Biography of Prof. Dr. Ahmet Ayhan Çitil
Prof. Dr. Ahmet Ayhan Çitil began his academic career with a double major in Industrial Engineering and Economics at Boğaziçi University. He then pursued his master’s and doctoral degrees in philosophy at the same university under the supervision of Prof. Dr. Yalçın Koç. He earned his master’s degree with a thesis titled An Introduction to the Ontological Foundations of Gödel’s Incompleteness Theorems and completed his Ph.D. in 2000 with a dissertation titled The Theory of Object in Kant’s Transcendental Thought and Some Consequences of a Deepening of This Theory.
In 2008, he conducted research as a visiting scholar at The City University of New York Graduate Center. After holding positions at Istanbul Technical University, Kocaeli University, and Koç University, he has been continuing his academic work at the Philosophy Department of Istanbul 29 Mayıs University since 2010.
His research primarily focuses on logic, metaphysics, the philosophy of mathematics, and moral philosophy. In 2012, he explored the possibilities of an object-centered philosophy of mathematics in his book Matematik ve Metafizik Kitap 1: Sayı ve Nesne. In 2023 and 2024, he published Kant Okumaları I. Kritik and Kant Okumaları II. Kritik, offering a comprehensive interpretation of Kant’s critical philosophy. Additionally, he has authored two textbooks on contemporary philosophy.
Prof. Dr. Ahmet Ayhan Çitil is recognized for his prolific academic output. He has published over 30 articles and conference papers and has delivered more than 50 academic lectures. Throughout his career, he has supervised numerous students, with 7 doctoral and 23 master’s theses completed under his guidance.
For his contributions to the academic world, he has received several prestigious awards, including the 2016 UFAD Uluslararası Felsefe Araştırmaları Derneği Felsefe Yarışması Büyük Ödülü, the 2017 Uluslararası Mehmet Akif Ersoy Bilim ve Sanat Ödülü, the 2021 Türk Felsefe Derneği Prof. Dr. Necati Öner Felsefeye Hizmet Ödülü, and the 2023 Necip Fazıl Fikir ve Araştırma Ödülü.
It can be said that one of the most distinguishing features of philosophical research is to reveal necessity or necessary relations. Philosophical studies also deal with the conditions of necessity without abandoning the ground of logic, criticism, and justification for all their investigations. The areas where necessity is “seized” are logic and mathematics. The outcomes reached in the field of logic and mathematics are not possible or probable; they are necessary and certain. The condition on which this necessity is based does not change over time; it is not subject to time. The necessity in logic and mathematics are not grounded on temporality or historicity. Although it is necessary to mention that both logic and mathematics emerged in human history with the emergence of language ability and its use in Homo Sapiens as a consequence of neural networks reaching sufficient complexity at a very early stage in history, this does not mean that logic and mathematics are historical sciences. The fact that they have been developed over time does not make them temporal, hence experiential. The condition and consequence of the neural networks reaching sufficient complexity are that an “intelligent being” as a biological creature “rises” to the stage of consciousness of the its self or self-consciousness, and accordingly, to the stage of the identity of self-consciousness, in other words, the ability to “rise” to the “unconditional” in the sense of being independent of experiential and temporal conditions and to carry out the thinking activity on this ground.
The formal condition that assures soundness of reasoning and to reach ‘truth’ about the object of thought is that the reasoning process does not encounter with contradictions or inconsistencies. Yet there is another conditions that assures detection of contradictions and inconsistencies; that is both the identity of the object of thinking and the identity of its sign (contextual or symbolic) are to be preserved during the reasoning process in general.
Wittgenstein expresses the issue in his own style in Notebooks as follows: “The obscurity obviously resides in the question: what does the logical identity of sign [Zeichen] and thing signified [Bezeichnetem] really consist in? And this question is (once more) a main aspect of the whole philosophical problem.” “The logical identity between sign and thing signified consists in its not being permissible to recognize more or less in the sign than in what it signifies. If sign and thing signified were not identical in respect of their total logical content then there would have to be something still more fundamental than logic.” [italics in the original] L. Wittgenstein. Notebooks 1914-1916. Trans. G.E.M. Anscombe. Harper Torchbooks, N.Y. 1961, pp. 3, 4.
I add the previously mentioned identity of self-consciousness as a ground condition to these thoughts: the identifier’s being spontaneously conscious of self-identity and its priority as a ground over each act of consciousness.
Dearest professor Teo Grünberg, in his 2020 World Logic Day declaration, spoke of the possibility of the grounds of “proto-logic” which makes all different logic systems possible – regardless of the logical systems and their applicability or application areas—but without being one of those logical systems (referring to Kripke and Robert Hanna).
Robert Hanna, in his book Rationality and Logic, to which Teo Grünberg refers, speaks of a “proto-logic,” through which all classical logic and first-order predicate logic with identity, as well as non-classical logic systems such as paraconsistent logic, extended logic, and alike, are established. I think there is a strong connection between what was said above about self-consciousness and its the relation to time and the understanding of “proto-logic”, and I sincerely agree with Prof. Grünberg that new studies should be done on this subject.
Finally, I would like to add the following about the importance and value of logic for humanity and morality: Those who study logic and/or those who teach logic have also contributed to philosophy and thinking differently. Those who make their way through the abstract reasoning structure encounter the issue of “rightness” when proving any logical theorem or testing the validity of arguments. In other words, they always have the tension of the thought “I shouldn’t take a step that I don’t have the right to” while moving forward in a chain of inference. They are aware that they are obliged to complete their proofs without taking unjustified or illegal steps.
Since, a step cannot be right, unless the laws and rules of thinking justify it. That is, the question of justification and being right is also required for any law, an axiom, or an additional rule. Thus, those who deal with logic experience the purest state of the “right” or “being right,” disregarding the psychological and emotional states. The same is true for mathematics and, to a certain extent, for the natural and social sciences, according to a scale of experiential content. For instance, this experience is required in the practice of the science of law to be isolated from arbitrary political pressures. Nevertheless, it is logic where its purest form is experienced.
Those who study and teach logic will significantly contribute to their students to the extent that they convey this vital idea and the mindset to their students. Perhaps the highest moral value that philosophy students can derive from logic is grasping and experiencing the concept of right based on necessity in its purest form.
Prof. Dr. Hasan Bülent Gözkân 14 January 2022
Biography of Prof. Dr. Hasan Bülent Gözkân
Hasan Bülent Gözkân was born in 1957 in İstanbul. He completed his secondary education at Saint Joseph High School and his undergraduate education in Civil Engineering at METU. He received his master’s degree in Philosophy from METU, with the thesis titled “Conventionalism in Geometry: An Instance of the Impact of Geometrical Systems on the Philosophy of Science” in 1992, and his doctorate in Philosophy from Boğaziçi University, with the dissertation titled “The Problem of the Constitution of Self and Reason in Kant’s Transcendental Thought” in 2000. He taught philosophy at Yeditepe, Mimar Sinan Fine Arts, İstanbul Technical, Galatasaray, and Boğaziçi universities. He was a visiting researcher in the Department of Philosophy at Clark University, the USA. He wor
The concept of “truth” evolved from Plato’s Idea or Aristotle’s Substance through the concept of “truth” of the Middle Ages and the concept of “essence” of the Modern Age to the concept of “postmodern truth” in the 21st century. This new conception of “truth” deformed its previous philosophical interpretations, since there is no “unique truth” anymore: “truth” depends on personal preferences and social choices.
The laws of logic had disappeared long ago, nothing left behind in terms of the traditional concept of “logic,” “sound,” and “reliable” logical thought. The new logical systems now reflect the “postmodern” character, too! Today’s concept of logic, requiring new definitions for the question of what logic is, makes it clear that we have now totally lost the traditional concept of “logic.”1
As it is well-known as a formal system, logic is undoubtedly independent of our daily language and intentions. On the other hand, social conditions and individual preferences that may characterize a particular way of thinking require some inference rules. We need inference rules for the ways of thinking as well as for the logical systems. Depending on economic, technological, scientific, cultural, historical, or theological conditions, every epoch reflects a particular way of thinking that is expressible through different logical systems. “Postmodern logic” characterizes not only different studies of logic but also our way of thinking and the paradigm of our century.
Paraconsistency, for instance, is a sound logical system making it possible for us to think in line with some controversial judgments found in theology and daily life.3 It looks like we will not be able to use the traditional definition of logic anymore. The most effective traditional problems like “believing or reasoning,” for instance, will not be meaningful anymore since the concepts of “reason” and “belief” lose their meanings together with “logic.” I believe that “solipsist logic”4 can provide us with new opportunities for elaborating on some old problems.
1 Cf. Jacquette, D. (Ed.) (2007) Philosophy of Logic, NH, Elsevier 2 Cf. Béziau, J.Y., Carnielli, W., Gabbay, D. (Eds) (2007) Handbook of Paraconsistency, Studies in Logic Vol. 9, College Pub. 3 Ural, S. (2019) Solipsism, Vernon Press 4İstinye University, İstanbul, Turkey
Biography of Prof. Dr. Şafak Ural
Şafak Ural was borned in Ankara in 1948. He graduated with a degree in Philosophy from Ankara University in 1971. After completing his studies, he continued his academic career at Istanbul University where he worked in the Department of Systematic Philosophy. In 1978 he received his doctorate for his thesis, “An Essay on the Determination of the Simplicity Principle in Positive Science”. Since finishing his doctoral thesis, Ural has worked as a visiting professor in Austria (Vienna and Innsbruck), the USA (Rutgers), Hungary (Budapest) and various universities in Istanbul. Attending many international conferences in the USA, Brazil, India and Singapore has allowed Ural to further develop his thesis on solipsism. He is the founder of the Department of Logics at Istanbul University and the Turkish Logic Society. He is also responsible for organizing several international conferences at Istanbul University.
One can construct nearly for every field of study a system of logic which is specific to this field. Many of these systems are extensions of first-order logic with identity (also known as classical logic). To list some of them, we have modal, epistemic, deontic, and tense logic. All of these are extensions of classical logic. But there are other systems that are not extensions of classical logic, like intutionist logic and quantum logic as some of the laws of classical logic do not hold in these systems. The applications of these systems in various branches of philosophy as well as science and mathematics are well known.
Alan Berger extensively discusses an important distinction Kripke had drawn in a graduate seminar he gave at Princeton in 1974. The distinction in a nutshell is between systems of logic, like the ones we have mentioned above, and logic itself. He raised the issue of whether we adopt a logic and likewise adopt an alternative logic. His conclusion is that the notion of “adopting a logic” is incoherent. His argument, which relies on an infinite regress, can be construed as follows. In order to investigate, understand or construct a new system of logic one would need an antecedent system of logic and so ad infinitum. Therefore logic itself cannot be one of the systems of logic. It is rather something that is presupposed by all presently constructed systems of logic or those that would be constructed in the future. Note that nothing else can be said for logic itself since once you attempt to explain what it is you already start constructing a new system of logic.
Perhaps the only way to stop the regress is to try to elucidate what logic is in non-logical terms. While recently reading Robert Hanna’s book Rationality and Logic published in 2006, I came across with an interesting division he made between “a single universal protologic” and “all classical and non-classical logical systems” we have mentioned above. He further claims that all logical systems are constructed by means of the protologic. Notice how this division is strikingly similar to Kripke’s contrast between logic and systems of logic.
In any case, Kripke touched upon an important issue about what logic is. I think it would be essential to have new studies on this subject.
Prof. Dr. Teo Grünberg 14 January 2020
Biography of Prof. Dr. Teo Grünberg
Teo Grünberg was born in Istanbul in 1927. He received his Ph.D. in Philosophy in 1964, Istanbul University. He became Assistant Professor in 1966, Associate Professor in 1970, and Professor in 1979 in the Middle East Technical University.
Teo Grünberg worked as faculty during 1962-66 in the Philosophy Department, Istanbul University, and during 1966-82 in the Humanities Department, Middle East Technical University as Chairman of which he was the founder. He retired in 1994 and worked in the same department as adjunct faculty during 1994-2002. He was also an adjunct faculty during 1968-79 in Philosophy Department, Ankara University, and during 1989-90 in the School of Engineering, Bilkent University.
Teo Grünberg in collaboration with his colleague Hüseyin Batuhan initiated the modern logic reform in high school teaching undertaken by the Ministry of Education, starting from 1966. He lectured during 1968-76 in the summer courses in modern logic for high school teachers organized by the Ministry. He initiated also the teaching of modern logic in various universities and contributed to the training of large number of faculties in this field.
He is the author of more than fifteen books and 35 articles, some of which published in international journals, in the fields of modern logic and analytic philosophy.
