In Memory of Horacio Arló-Costa

I am deeply saddened to have recently learned that Horacio Arló-Costa, Professor of Philosophy at Carnegie Mellon University, passed away.  He was my advisor and kind friend. His friends, family, and colleagues will miss him dearly.

Please feel free to share your memories of Horacio.

Horacio’s family will hold a visitation on Saturday, July 23 from 2:30 to 5:00 PM, and from 7:00 to 9:00 PM, at the Thomas Quinn Funeral Home:

35-20 Broadway
Long Island City, New York 11106

Horacio’s burial will take place at 11:00 AM on Sunday, July 24 at Ferncliff Cemetery:

280 Secor Road
Enter through Gate 1
Hartsdale, New York 10560

For directions, please see

Horacio’s wife Claudia has asked that well-wishers, instead of sending flowers, donate to a Scholarship Fund in the name of Dr. Horacio Arló-Costa being created by The Department of Philosophy at Carnegie Mellon University.  Information regarding this Fund will be available shortly at

41 Responses to In Memory of Horacio Arló-Costa

  1. Catarina Dutilh Novaes says:

    I have very fond memories of Horacio from the time I lived in New York and attended R. Parikh’s group’s weekly seminar, where Horacio was also always present. We’ve also corresponded a few times in his capacity of editor of JPL and then RSL. Perhaps most important was our South-American complicity, actually🙂

    Thanks for posting the sad news, and please keep us posted on future developments (memorials, possibly special editions on his work etc.)

  2. Edouard Machery says:

    This is a terrible news.

  3. Eric Pacuit says:

    I learned a great deal from Horacio about philosophical logic, rational choice and the foundations of probability. I will always remember our extensive discussions in cafes in NYC and email exchanges. He was a pleasure to work with and a brilliant mentor. I am very sad not to have the chance for more collaboration and to miss out on pleasant conversations over a cappuccino.


  4. Christian List (also on behalf of Episteme) says:

    I am writing personally and also on behalf of the editorial team of Episteme. We are deeply saddened to learn that Horacio has passed away. Horacio was a wonderful person, friend and colleague, and an outstanding scholar. We will miss him.

    Just a few weeks ago, Horacio organized this year’s Episteme Conference at Carnegie Mellon University, which was a great success, and he and I were in the process of co-editing a special conference issue of Episteme, on “Formal Social Epistemology”. It’s been a privilege working with him. We will now dedicate this issue to the memory of Horacio.

    We wish to send our warmest thoughts and condolences to Horacio’s family and friends.

  5. Horacio was one of the finest scholars in our field. Erudite, original, encyclopedic, exquisite. As fine as they come. Horacio was also a good friend. He will be so sorely missed profesionally and personally. A truly great loss to philosophy and its broader intellectual environment.

  6. Michael Shaffer says:

    I spent the Fall 2010 semester at the center for formal epistemology at CMU and sat in on Horacio’s seminar on Ramsey. It was a pleasure to have been able to learn from him. He was also a great host, a kind and helpful person and truly supportive of the work of others.

  7. Although I had not seen him in a while, Horacio was a friend. This is a great loss for the field. I remember especially Horacio’s service to the JPL and to the RSL. He will be missed.

  8. We received from Horacio the best support in Pittsbugh during my sabbatic year there in 1989. He has been a real friend to me and Margherita. We keep a vivid memory of his as great scholar and wonderful person, our meetings in Genoa and Trento, his ability to keep in touch on our different interests. We miss him a lot.

    • By the way, it was 1998 (not 1989!) and Horacio was for us a surprise: he was able to pass from probability theory and causal relations to Fregean conceptions of sense and Kripke’s puzzle. He was at his first years at Carnegie Mellon and was working for tenure (which he had later and he was very happy of the appreciation given by Ruth Barcan Marcus). We miss his unvaluable mixture of ability of treating formal aspects and keeping always in touch with what is important in life. His last suggestion in May 2011, in sending me the proofs of his paper of indeterminism and change , was to go back to the formalization of some aspect of Nozick’s notion of knowledge in a paper he wrote with Rohit Parik in 2006.

  9. Horacio was always quite generous as an interlocutor and a correspondent, and he was extremely conscientious in his service to the profession at large. A great loss (especially for formal philosophy).

  10. Jeff Helzner says:

    Some weary thoughts about Horacio:

    I met Horacio when I arrived at CMU as a graduate student. It was early during my time at there that Horacio introduced me to some theoretical aspects of logic-based AI. This was somewhat of a revelation to me, since I had come from a background in pure mathematics and was still treating logic like a branch of abstract algebra. These interactions motivated me to study modal logic under Horacio, first in a course and then later as an independent study. Horacio’s views on the subject, especially his very original work on first-order modal logic, provided a nice contrast to some intriguing ideas that Steve Awodey and Dana Scott were exploring in connection with category theory and issues in constructive mathematics. Horacio also served as a member of my dissertation committee. While Teddy Seidenfeld was my main advisor, Horacio, who was not tenured at that time, joined us for our regular meetings in Baker Hall. I recall those meetings – which were often held in Horacio’s sparingly disheveled office — with great fondness.

    It was during those regular meetings that I first became acquainted with a certain tradition in American Pragmatism that seemed to run from Peirce to Isaac Levi, who served as dissertation advisor to both Horacio and Teddy. It should perhaps be noted, so as to avoid confusion, that this particular tradition is not a major part of what now counts as pragmatism – lest we forget, Peirce himself suggested renaming his position as pragmaticism. At that time I assumed that Horacio had accepted certain aspects of Peirce’s thinking, especially the belief-doubt model. It was only years later that I learned the extent to which some of his ideas were in conflict with Peirce’s account of inquiry. My rough sense is that this is most clearly expressed in Horacio’s interest in developing a version of radical probabilism that avoids various well-known difficulties. I don’t think that there is much hope in taking “The Fixation of Belief” seriously if it is probabilities all the way down. Another point of tension with the sort of pragmatism that he absorbed at Columbia might be seen in connection with his work on epistemic interpretations of modal logic – roughly, this tradition of epistemic logic might be seen as emphasizing a third-person perspective in contrast to the first-person perspective that is emphasized in the belief-doubt model.

    After graduating from CMU, Horacio and I continued on a research project that was ultimately concerned with the relationship between normative and descriptive theories of decision making. More specifically, though only roughly, psychological work on decision making often assumes a particular account of rational choice — e.g., expected utility maximization — and then offers empirical evidence to show that there are systematic deviations from the account that is assumed. This provides a way of critiquing certain ideas in the foundations of economics. But this raises a question: are there contexts in which such deviations should instead count against the normative status of the given standard of rationality? In our most recent joint work in the area we were attempting to show that the so-called “description-experience gap” — which Ralph Hertwig, Greg Barron, Elke Weber and Ido Erev had discovered in the context of decision making under risk – could be extended to decision making under uncertainty.

    Horacio was also keenly aware of the various movements and currents within his areas of research. He had a vision for the emerging cluster of topics that now count as formal epistemology, broadly construed. He had just helped to found the Center for Formal Epistemolgy at CMU. We had just finished editing a second collection of papers on the foundations of the decision sciences. Along with Vincent Hendricks and Johan van Benthem, Horacio had just finished editing a major collection in formal epistemology. Horacio, Vincent, and I were planning a book-length project on formal epistemology. Of course he was also served as an editor for JPL, RSL, and Synthese.

    After I moved to NYC, Horacio and I would meet for lunch during his frequent visits to his place in Astoria. We would pick a particular place and then make it our official meeting place for the next several months, or perhaps a bit less if the place went out of business. Horacio loved jazz, as I do. I wish we had gotten to more shows. The time we heard Fred Hersch play was especially memorable. The memories remain.

    I just searched my CU email and found about 1500 messages from Horacio. The final message, sent on July 13, reads as follows:

    “I am waiting for a flight in the capital of Iceland (Reykjavik). Hope to arrive to NYC at 7:00 pm. I will call you then.


    He never called. His body was discovered on the following day.

  11. It turns out that, at least in Portugal and Germany, it is easy getting a divorce but practically impossible to get married, which is exactly the opposite of how things go in the US.

    I had a talk scheduled at Parikh’s CUNY seminar, which Horacio had arranged. After regaling Horacio with tales of bureaucratic excess, impossible requirements, embassy interventions, and translators with certifications and stamps to work with four different languages, I told him that Monika and I had given up on a Berlin wedding and were adding a day to our NYC trip to get married at the Manhattan Clerk’s office. Twenty-five bucks. Twenty-four hours. Two passports. Done.

    I remember Horacio’s arched brow, sideways glance, and wry smiles during this, adding with perfect comic timing an understated “that’s right, that’s right.” It was jazz.

    So naturally we all ended up at the Standard to see Charles McPherson after the ceremony, which Horacio had also arranged. I’ve had McPherson on all morning.

    He and I last laughed together over Skype a month ago, or maybe it was the end of May. He was in California at the time, and brimming with plans. And last week we exchanged a volley of messages, an exegetical disagreement over how similar (Horacio!) or how different (me!) Kyburg’s and Levi’s notions of ‘reasonable possibility’ are. The exchange drew out Horacio’s colossal, encyclopedic knowledge, and his sharp, penetrating mathematical and philosophical insights.

    The thread broke off, unresolved. I thought at the time that we would return to it. That we would write again. And that we would laugh again.


  12. Estoy absolutamente impresionado con esta noticia: la última vez que ví a mi amigo Horacio fue durante la conferencia en su visita a Buenos Aires (2010). A mediados de los 80, aquí en Buenos Aires, yo era músico professional y paralelamente estudiaba Arquitectura. El estaba terminando la carrera de Filosofía y tenía un gato llamado Zenón de Elea. Manteníamos larguísimas conversaciones sobre arte y ciencia. Vacacionábamos juntos. A pesar de la distancia y del tiempo transcurrido, siempre percibí un sentimiento compartido, una suerte de hermandad tácita, pues para mí Horacio era —y no solamente por compartir el nombre— una suerte de otro yo: era mi lado racional “extremo”, teoremático. Horacio fue para mí, un maravilloso guía, pues me hizo aproximar criticamente a muchísimos autores que marcaron mi formación. Poeta y fantástico escritor, a él le debo, de alguna manera, entre otros, el descubrimiento de Wittgenstein y de Felisberto Hernández, un extraordinario escritor uruguayo que ambos admirábamos profundamente. Pueden leerlo: hay algo de Horacio en él. Lo voy a
    extrañar. Mucho.

    Profesor Horacio Wainhaus
    Universidad de Buenos Aires

  13. Klaus Nehring says:

    I have gotten to know Horacio only a year ago, but we seemed to build a strong rapport quickly. From the beginning, I was attracted by Horacio’s thoughtfulness, open-mindedness and kindness. With this grim news, what may have been will not be.

    Just a few weeks ago, on the evening before the Episteme conference which Horacio had organized, and while he was still busy with many last-minute issues, we had an intense and probing discussion about radical probabilism, rational choice under ambiguity, rationality and behavioral evidence, and other topics. A rare treat which will stay with me for a long time! Like many of you, I felt there was more, much more to come.

  14. My first contact with Horacio was an exchange of emails, two years ago, and in this one and those which followed, he always answered thoroughly, promptly, and in a helpful way. We often wrote about meeting each other in person, and were both looking forward to it.

    We eventually did a few weeks ago, ahead of the Episteme conference. Horacio was busy with the last-minute details, but he found time to meet together every day. Although we discussed matters of common academic interest, we shared many anecdotes about our personal lives as well.

    Horacio’s philosophical acuteness and generosity in sharing ideas were amazing, and my future work will be substantially shaped by the brief exchanges we had then. Reading your testimonials, I now know that many have experienced in the same way Horacio’s kindness, congeniality, and generosity.

  15. simone duca says:

    I’ve met Horacio only once. It was in Konstanz for the FEW ’10. He was kind enough to sit in my talk and, at the end, he asked two brilliant questions that help improving the final version of the paper. Later it turned out that Horacio was one of the referees of that paper. His comments were the most insightful, relevant and fair.

    A few months ago we started a correspondence on decision making and different notions of utility. I was really excited about that. Whenever I spoke with Horacio, it felt there was so much to learn from him and that he wouldn’t spare his energy in sharing his vast knowledge.

    As many others, I will miss him a lot.


  16. Cristina Bicchieri says:

    La duda es uno de los nombres de la inteligencia
    (Doubt is one of the names of intelligence)
    J.L. Borges

    Horacio entered my life as a young colleague when he joined CMU. We naturally became friends, as we shared similar interests in philosophy, cinema and literature. My most vivid memories of him are the trips we have taken together over the years. I fondly remember the special time we spent in Florence. We used to meet every morning in the garden to discuss belief revision in games, as at the time we were writing a paper on that topic. These lively discussions continued at CMU, where we often would stay into the night debating over an argument. Horacio always struck me as somebody who could be very serious and intense one moment, and unabashedly fun the next. He was passionate about his work, his life, his friends.
    Even after I left CMU, we have kept in touch. Whenever I traveled to New York, he invariably offered to take me to jazz concerts. I owe it to him if I now understand and appreciate that genre. He was fascinated by the experimental turn my research had taken of lately, and we always thought of writing a new paper together, as he got more and more interested in behavioral decision-making. As a matter of fact, he had promised to visit Philadelphia this coming Fall, and I was really looking forward to spend some time together.
    Last time I talked to Horacio was April, and he sounded happy. He was going to Europe and had, as always, many projects in mind. I cannot believe I will no longer be able to enjoy his intellectual vivacity and humor, as he was the friend with whom I shared the rarest blend of intellectual and personal affinity.

  17. Rohit Parikh says:

    I had dinner with Horacio on Monday in Groningen in a rather large plaza. There were just the two of us. Usually, as a true Argentinian, he insisted on eating meat, but that day he had the same goat cheese and salad that I did. I do not know if this has a meaning. He was extremely depressed and on the way back to the university guesthouse he asked me what I thought of his work. I said that he was a very important person in the foundations of probability.

    The next day I saw him briefly and later sent him an email that I was worried about him. He responded “Unfortunately and unexpectedly problems continue to pile up in the personal front and so I decided to return to the states to handle them in the best way possible.”

    That was the last I heard from him, until I got the sad news through an email from Jeff Helzner. A terrible loss for philosophical logic.

    I have known Horacio since before he got his doctorate. I was on his dissertation committee and remained in close contact during the years. Even though CMU is an excellent place, I knew that he could not be happy in Pittsburgh when his wife was in New York. And perhaps also he was much too sophisticated person to be happy in Pittsburgh. He clearly belonged in a major cultural center.

    Michael Devitt and I pursued a plan of bringing him to CUNY but it did not work out. And eventually his loneliness (despite so many loyal friends as we see here) caught up with him.

  18. Juliet Floyd says:

    I am very saddened by what has happened.

    The times I spent in Horacio’s company, when we were both around at CUNY in the 1990s, meant a great deal to me. He made a remarkable impression that sticks in my memory: how he ate, how he spoke, how he explored and questioned. Our discussions were filled with his contagious sense of fun, culture, seriousness, and philosophical breadth. I learned much from him about belief revision theory and why it matters to philosophy. He had a capacious and creative mine. I’m thankful to Rohit Parikh for facilitating our conversations.

    The profession has lost a very gifted philosophical logician. The world has lost a very special and vibrant person.

    Juliet Floyd

  19. Luca Rossi says:

    No todo està perdido si no te lo tomas en serio
    (Not everything is lost if you don’t take too seriously)

    I first met Horacio at Ezeiza airport in Buenos Aires. It was 1988. I was a young italian Ph.D. student, with a scolarship to spend in Argentina, and he was the best pupil of prof. Carlo Alchourròn. He picked me up at the airport and then he was my “Virgilio” for the following weeks, guiding me in the discovery of Baires secrets and beauty. With his uncomparable sense of humor, his clear and amazing intelligence, his warm humanity and generosity. Since then a strong and sincere friendship arose, which lasted during the years up to now. We shared a flat in Pisa during his “Italian period” in the ’90s and then met again sometimes in the following years, in Italy and NYC. Always feeling the same sense of being-in-touch at some profound level, notwithstanding the distance, the time passing, and the different courses of our lives. He was like an older brother to me. I will miss him forever. May his spirit be at ease, wherever it is.

  20. Alejandro Cassini says:

    Very sad news, indeed; we are all shocked here, as they are his friends everywhere.
    I’d like to remember Horacio’s older times, before his moving to the US. I’m relying on my memories so some facts or dates may be not completely accurate.
    Horacio was born in Montevideo but he was educated in Buenos Aires. I met him at Buenos Aires University in 1986 when, rather by chance, he was my student. I then was a second-year grad student working as TA in a course in Metaphysics. Horacio, three years older than me, was a senior undergrad at the Philosophy School. After a few weeks, I realized something quite obvious: I couldn’t teach very much to such a smart guy. When I was still looking for my way in Philosophy, he already was firmly on his track. Horacio started his philosophical studies later, after studying Biology and Engineering; but then he progressed very quickly.
    When we met in that course he was working with his first advisor, the late Carlos Alchourrón, on highly technical issues in logic. It was the time in which the AGM theory of belief revision was a fresh novelty, but still a secret for a few initiated. It was also the time of the newborn democracy in Argentina; an epoch of hopes and cultural renewal. Horacio, still a student, was so competent in logic that Alchourrón used to test his new ideas with him. That was how he introduced Horacio into the topics of conditionals and defeasible reasoning. In turn, Alchourrón, a lawyer, learned some mathematics from Horacio, who had a solid scientific background. Many years later Horacio told me that Alchourrón disliked probabilistic approaches to logic because he, as many philosophical logicians, “was afraid of numbers”. Horacio was certainly not, as his works showed.
    For some years in the late 80’s we shared philosophical discussions, travels, conferences, coffee talks, and perhaps also certain life ventures. In the early 90’s, after spending a year in Milano, he left Argentina for good. His American career is well known. We met again in New York City during the years 1998 and 1999, when I lived there. He already was a respected teacher and philosopher. As always, he was kind and generous with his friends. I saw him after many years in 2010, when he gave a talk in Buenos Aires. He looked very tired that evening, almost exhausted. Perhaps he had been traveling too often and working too hard. His was a restless work, I dare say. He devoted his entire life not just to philosophy but to wisdom and culture. He enjoyed that, I have no doubt. He enjoyed his life.

  21. I have met Horacia at several conferences; most recently at the Episteme Conference at Carnegie Mellon University. He planned to contribute to our Duesseldorf conditonals proceedings. I had most interesting discussions with him. He was one of the deepest formal philosophers that I knew who at the same time had an extremely broad spectrum of interests. I was shocked about his sudden death. We have lost a great philosopher and wonderful person.

  22. Gabriella Pigozzi says:

    I am so sad and still in disbelief to be speechless. Borges’ “The Just” will always remind me of Horacio.

    Los Justos

    “Un hombre que cultiva su jardín, como quería Voltaire. El que agradece que en la tierra haya música. El que descubre con placer una etimología. Dos empleados que en un café del Sur juegan un silencioso ajedrez. El ceramista que premedita un color y una forma. El tipógrafo que compone bien esta página, que tal vez no le agrada. Una mujer y un hombre que leen los tercetos finales de cierto canto. El que acaricia a un animal dormido. El que justifica o quiere justificar un mal que le han hecho. El que agradece que en la tierra haya Stevenson. El que prefiere que los otros tengan razón. Esas personas, que se ignoran, están salvando el mundo.”

    The Just

    “A man who cultivates his garden, as Voltaire wished. He who is thankful that there is music on earth. He who discovers with pleasure an etymology. Two workmen who play a game of chess in silence in a southern café. The potter who contemplates a colour and a form. The typographer who sets this page well, though perhaps it does not please him. A woman and a man, who read the last three-line stanza of a certain canto. He who strokes a sleeping animal. He who justifies or wishes to justify a wrong done to him. He who is grateful for Stevenson’s existence. He who prefers others to be right. These people, who do not know it, are saving the world.”

  23. Achille Varzi says:

    I can only add my sadness. I’ve known Horacio since my very first day at Columbia, when I came for my job talk in 1995. He showed me around, introduced me to his fellow students, took me to the Strand Bookstore, and then out to jazz. I can’t believe he’s gone. He was an extraordinary philosopher and an extraordinary person. We’ll miss him immensely.

  24. What a shock! Horacio was on my MS committee and the clever, helpful teacher of several of the classes I took while at CMU. I remember receiving 3 pages of comments on a 12 page paper in his epistemology seminar – this is dedication, and fairness, as everything was a way to improve, to learn, to further the state of the disciplines the work was about.

  25. Scott Shapiro says:

    It’s been very comforting for me to read the various remembrances on this blog. Like all of you, I was (and still am) shocked by the loss of Horacio and I cannot believe that I will never see him again. It is nice to know that Horacio touched so many people in the way that he touched my life.
    Horacio was my best friend in graduate school. We were pretty much inseparable. We spent many hours each day discussing the finer points of modal logic, the Limit Assumption, Convention T, the Levi Identity and, of course, AGM. I knew very little logic coming into graduate school and Horacio taught me pretty much everything that I know about the technical aspects of philosophy. Horacio was extremely generous in this regard. He was giving and patient – in fact, I can’t recall a time that he got frustrated with my lack of comprehension. He was not only kind, but he loved philosophy so much that he wanted you to love it too. And his enthusiasm was contagious.
    Horacio was extremely generous in another way. He would essentially give away his results if he wanted to work with you on a certain topic. The paper we wrote together on mappings between non-monotonic and conditional logic was his idea and he very graciously agreed to let me work together with him developing the details of the mappings and to share the credit. The summer we spent together working day and night on the blackboards in the bowels of the Computer Science building at Columbia were among the happiest of my life.
    Though we took very different routes after graduation, Horacio would write me every few years not only to see how I was doing but also to find out what I was working on. He was an unusually open intellect. Everything interested him. And his greatness stemmed from this openness. He wasn’t the most gifted technician but he was extraordinarily creative. He would make connections that no one else would see and was able to do so because he was listening and reading and taking everything seriously.
    The last time I heard from Horacio he sent an email to congratulate me on the publication of my book. We talked about trying to formalize certain aspects of the theory I developed there. In my mind’s eye, he and I would be back in the Computer Science building, chalk dust all over our clothes, hoping up and down about some lemma and having the time of our lives.

  26. Jim Joyce says:

    This is terribly sad news. Horacio was a wonderful man and a first-rate philosopher, a pleasure to deal with in every way. In my experience, he possessed a rare kind of dignity that let him handle situations and people, sometimes difficult situations and people, with great grace and wisdom. I always found his philosophical insights thought-provoking and profound (especially his lucid criticisms of my own work, which were invariably constructive and, unfortunately for me, almost always on the mark). He wrote a slew of good papers over the years — I very much hope that people will continue to give them the attention that they so richly deserve. I especially like his 2001 *JPhil* piece on Bayesian epistemology and import-export laws and the 2006 *Phil Studies* article “Rationality and Value…,” but there are many others. I will always fondly recall a long afternoon, spent in Horacio’s office at CMU, when we spoke at about belief updating and imprecise probability theory. It was a thoroughly enjoyable occasion, both for the philosophy and for the company. We all lost something with Horacio’s death.

  27. Paul Egré says:

    I am terribly sad and shocked to hear about the death of Horacio. Just a few weeks ago he wrote to me to say he would spend some time in Paris during the second half of July and we had planned to get together and have lunch during his visit. I was still looking forward to that meeting when I got the terrible news tonight.

    Horacio was a wonderful person and a great mind. I was first in contact with him in 2006 as he was the editor in charge of a paper Denis Bonnay and I had submitted to the JPL. He was a highly professional and attentive editor. The paper went through three meticulous rounds of refereeing and I remember we got a very helpful but potentially devastating review after first revisions that revealed an important mistaken claim in one place. Horacio however gave us a chance to fix it and to resubmit what became a much more elaborate work. I then met Horacio for the first time at the conference on Dynamic Epistemic Logic that Olivier Roy, Mathieu Marion and Patrick Girard coorganized in Montreal in 2007. We met again on two equally memorable occasions after that: in 2009 at CMU, at the FEW conference that Branden Fitelson was organizing that year. And in 2010, again at CMU, for the opening ceremony of the Center for Formal Epistemology. Both of these visits to CMU left very big impressions on me, and I keep vivid memories of Horacio, of his generosity and gentleness as a person and as a philosopher, and of the great inspiration he was contributing to the department there.

    The loss of Horacio will be a loss for the entire community of formal epistemologists. I wish to express my profound sympathy to his family, to his friends and coauthors, and to all his colleagues and students at CMU. We will miss him a lot.

  28. Jake Chandler says:

    I met Horacio at a conference on conditionals in Leuven a few years ago and had the opportunity to subsequently correspond with him on a variety of topics, ranging from belief revision to decision theory, through deontic logic.

    His immense kindness, enthusiasm and intellectual generosity left a deep impression on me. This is a very sad and shocking loss for the whole community, and for all of those who had the privilege to cross paths with him.

  29. Like everyone else who knew Horacio, I too was deeply saddened to learn of his passing. He was one of the kindest, most thoughtful people I knew in philosophy. I knew him primarily through having gone to graduate school with him; if memory serves we entered Columbia’s PhD program in the same year. I had only seen him and talked with him sporadically in recent years. Still, I have many vivid memories from our graduate school years of the encouraging words he would give to me, and to others, whenever he saw that we were down. Since then I have often had that image of him in mind when I consider the standards to which each of us ought to hold ourselves in our professional and personal dealings with others. May his memory serve as an inspiration to all of us; Horacio, you will be dearly, dearly missed.

  30. Patrick Blackburn says:

    A considerate and helpful colleague. A genuine and kind man.

  31. Rohit Parikh says:

    On July 11, the TARK XIII conference gave a party in Groningen for the attendees. Afterwards, Horacio and I had a small dinner in a plaza in Groningen. Only two weeks have passed and he is already gone.

    But he will be honored by various events at Columbia, at CMU and most likely also in Munich and in Buenos Aires.

    For me, he was a student who became an affectionate and long standing friend. We met each other frequently in New York, where he gave several talks at CUNY. But we also met in Pittsburgh, in Florence (where he introduced me to Vann McGee), and of course in Groningen. He knew my family and I knew his wife Claudia.

    Horacio was a person of immense scholarly integrity and an ability to produce impressive original research. He was surely a world expert in the foundations of probability and aspects of conditionals and modal logic. It was quite frequent for me to ask him a question and get an instant answer. Some have said he was a walking encyclopedia. This is a fair assessment.

    He shared my interest in Borges (or perhaps I shared his), in Tagore, and in Blake. There was a deep spiritual sense in him, which apparently his father also had and which he celebrated in his eulogy to his late father. I read part of the same eulogy at Horacio’s funeral in Westchester. What Horacio said about his father, in large part, applied also to Horacio himself.

    I am sure his work will be carried on by others, especially his student Arthur Paul Pedersen. I look forward to being in touch with Paul, with Horacio’s colleagues at CMU and his many friends at Columbia.
    Rohit Parikh

    • Rohit Parikh says:

      Here is the poem by Hesse that I read at Horacio’s funeral:

      As every flower fades and as all youth
      Departs, so life at every stage,
      So every virtue, so our grasp of truth,
      Blooms in its day and may not last forever.

      Since life may summon us at every age
      Be ready, heart, for parting, new endeavor,
      Be ready bravely and without remorse
      To find new light that old ties cannot give.

      In all beginnings dwells a magic force
      For guarding us and helping us to live.
      Serenely let us move to distant places
      And let no sentiments of home detain us.

      The Cosmic Spirit seeks not to restrain us
      But lifts us stage by stage to wider spaces.
      If we accept a home of our own making,
      Familiar habit makes for indolence.
      We must prepare for parting and leave-taking
      Or else remain the slaves of permanence.

      Even the hour of our death may send
      Us speeding on to fresh and newer spaces,
      And life may summon us to newer races.
      So be it, heart: bid farewell without end.

      – Hermann Hesse

      I found this poem completely by chance as I was sorting through some papers on Saturday.

      And here the paragraph from Horacio’s eulogy to his own father which I also read:

      My father had also a deep sense of religiosity that helped and comforted him while passing through difficult periods of his life. Under this point of view I hope that his soul rest in peace after a long and fecund life. I only realize now how deeply he influenced me in various ways and how proud I am of him and the way in which he contributed to his beloved country and conducted his professional and intellectual life.

      Much of this applied also to Horacio himself.

  32. Along with Horacio’s family, friends, and colleagues, yesterday I gave an eulogy at Horacio’s funeral based on the following text.

    In Memory of Horacio Arló-Costa

    Horacio Arló-Costa was a logician, philosopher, and interdisciplinary guru. His innovative research contributed to many different fields, much in the spirit of Carnegie Mellon’s interdisciplinary outlook.

    He was known as a walking encyclopedia, an exceptional academic to consult to acquire a survey of a field of study and its latest, interesting open questions.

    Horacio was also known as a passionate interlocutor, prepared to propound and defend a position intelligently and with scholarly eloquence.

    And he was an inestimable advisor, a mentor who by collaborating with his students would impart and cultivate invaluable skills and knowledge, a man who inspired and encouraged.

    I was one of his students, and through our continuous collaboration and frequent discussion we became very close friends.

    Our joint work resulted in several publications addressing issues that extend across a diversity of fields, such as philosophical logic and formal epistemology, normative and behavioral decision theory, and philosophy of science and philosophy of language. Just recently two articles we had worked on together debuted in print, and we had just finished another article. Although we disagreed about various issues which arose while we worked together, we were capable of agreeing to disagree, a virtue of our partnership we both recognized and embraced, one of many virtues which brought us together for an ongoing collaboration. Either on the horizon or in flight with us, a number of projects excited and inspired our hard work and creativity.

    I am not alone in this regard, of course. Horacio collaborated with numerous talented people, so many so that a list would be too long to expound, and any abbreviated list would surely be too difficult to defend. Let me assert unconditionally, however, that Horacio himself made his unique, significant mark on fields inside and outside of philosophy, both as an academic and as a person. And let us now turn to Horacio the person.

    Those who knew Horacio the person recognized him as a sort of Renaissance man. He loved jazz, adored literature, deified science, and consumed massive amounts of coffee, with a penchant for a skim cappuccino sprinkled with Sugar in the Raw.

    Equipped with a sophisticated yet sometimes coy sense of humor, Horacio mischievously admitted, on a number of occasions after observing its comical effect, that he dined several times a week at Pamela’s Diner, a hearty and wholly unhealthy breakfast joint.

    Horacio the person provided unconditional support for me academically and personally. We met frequently, during the week and over the weekend, for food, drinks, and conversation, both shop talk and charlas.

    Although Horacio and I communicated frequently after he departed for Europe and before his untimely death, I would like to share an anecdote taking place the day before Horacio departed for Europe.

    On that day, a Friday, Horacio and I decided to meet in the afternoon at a coffee shop on Walnut Street, close to his residence in Pittsburgh. Mauren, my girlfriend, who is generally cheerful and bright, was having an unusually lousy day, and in an e-mail message notifying her of my afternoon plans, for some reason I resorted to absurd pet names in the style of the well-known Seinfeld episode:

    Hi Oatmeal Honey Cakes,

    I am going to leave in a bit to meet the H-man.

    Paul Pancakes

    I had never called Horacio “the H-man” before, but its jazzy ring sounded right for my purpose, which was to cheer up Mauren. Immediately before I left for Walnut, where I would call Horacio to let him know I was nearby, he sent me an e-mail message:

    Dear Paul:

    I suspect that this [message] was not intended for me🙂 In any case, I will be here at home. Just give me a call or send me a message if you want to meet anytime.

    The H-man.

    When I laugh about this, I think about Horacio reading my message, grinning and chuckling. (I owe thanks to Teddy Seidenfeld, my wonderful co-advisor, who reminded me of this story.)

    Though he was a gentle person, Horacio was a passionate man with a great sense of humor. And I wish I had some more time to share other anecdotes which bring out other aspects of Horacio the man, a rich complex.

    Horacio will be sorely missed—I would like to say by me most of all—but of course, like Horacio himself, I will try my best to be gracious and just, sharing my grief equally with his friends, family, and colleagues.

    Friends and family know that Horacio had a special love for the writings of Argentinean Jorge Luis Borges. On several occasions Horacio presented me with a book as a gift for one reason or another, and on one such occasion he presented me with a collection of writings by Borges. I close with a translation of one of Borges’ solemn poems, in honor of Horacio Arló-Costa, scholar, advisor, and close friend.

    The title of the poem is “In Praise of Darkness.”

    Old age (or so it is called)
    can be a time of joy.
    The creature has died or has almost died.
    The man and his spirit remain.
    I live among forms of lightness and haze
    yet, not among darkness.
    Buenos Aires,
    whose edges disintegrated,
    toward the endless plains,
    had come to be la Recoleta, el Retiro,
    the hazy streets of Once
    and the shaky old houses
    that we still call the South.
    In my life there were always too many things;
    Democritus of Abdera gouged out his eyes to think;
    Time has been my Democritus.
    This semi-darkness is slow and gentle;
    flowing down a peaceful slope
    it appears to have no end.
    My friends are faceless,
    women are what they were many years ago.
    The street corners could be from anywhere,
    the pages of books are without words.
    All of this should intimidate me,
    but it is a sweetness, a return.
    Of all generations of texts that exist on the Earth,
    I have only read but a few,
    I continue reading them in my memory,
    reading and transforming.
    From South, East, West and North,
    the paths converge that have brought me
    to my secret center.
    These paths were echoes and steps,
    women, men, agonies and triumphs,
    days and nights
    visions and dreams,
    each tiny instant of yesterday
    and the yesterdays of the world
    the steady Danish sword and the moon of Persia,
    the acts of the dead,
    the love shared, the words,
    Emerson and the snow and so many things.
    I can now forget them. I’ve found my center.
    My algebra and the key
    to myself.
    Soon I will know who I am.

  33. Varun Dutt says:

    I first met with Horacio when my adviser, Dr. Cleotilde Gonzalez, Dr. Jeff Helzner, and I starting collaborating with him on trying to replicate the “description – experience gap” for decisions under uncertainty. I saw Horacio first time in my adviser’s office on 02/12/2010, where Horacio limped around with a twisted ankle (which he had twisted by slipping in snow a few days earlier).

    Since then, I met with Horacio on numerous occasions while meeting him in the Porter Hall corridors or seeing him in the CMU shuttle (the last meeting was during his lecture on our project in the Philosophy Department’s seminar series at Carnegie Mellon). On each of these occasions, I found Horacio to be a gentleman, an expert in his field, and one who was very calm at discussing difficult concepts and scholarly disagreements.

    Most recently, I had got to know that Horacio had lost his father and being very close to his father he sounded upset and heart broken on the sad news. Horacio’s sudden loss came to me as a shock and for sometime I was unable to reconcile the sad news. I will miss Horacio and I will try my best to complete the project he started with me, Coty, and Jeff. I believe Horacio would have wanted the same. My sincerest sympathies will be with his family. I will always fondly remember Horacio to be a great friend and a philosopher.

  34. Kevin T. Kelly says:

    Wow. Horacio finished his career with an existence proof that full belief revisions do happen. I heard the news in Kyoto, where I was giving a pair of lectures, and when I finally cognized what the email said, my first reaction was to contact Horacio to put together a suitable event.

    I have known Horacio as a colleague since he started at CMU. During that time, we talked extensively about belief revision, learning, imaging vs. belief revision, and more recently about bounded rationality and acceptance. We shared a deep commitment that formal philosophy be philosophy that is precise rather than mathematics looking for an application. We also shared a deep commitment to the Center for Formal Epistemology (CFE) at Carnegie Mellon university, of which Horacio was the founding co-director, for the last year of his productive life. Our motto for the first year of CFE operations was “pedal to the metal” and we managed to plan and execute six workshops in the first year of operation. Horacio and I didn’t have much time for discussion. A poignantly raised eyebrow exchanged in the hallway on the way to classes spoke volumes about the work load. But in spite of all the pressure, Horacio cherished the CFE’s success and in a sea of distractions was always happy to make time for its business. Of course, business meetings always evolved into a two or three hour discussion of recent results on belief revision, simplicity, conditionals, acceptance, and bounded rationality.

    My long days in the office always ended with a tired walk past Horacio’s office wing, prior to a forty-five minute walk through a wooded canyon to my house (yes, in Pittsburgh such things are possible). I always felt the urge to stop and talk philosophy with Horacio. Sometimes I did, and then we would talk until 9. It will be a lonely walk indeed this Fall.

  35. José Seoane and María Fernanda Pallares says:

    We have learned with deep sorrow of the passing away of Prof. Horacio Arló Costa. We met Arló Costa not long ago in a meeting with teachers of our University while he was on holiday in Uruguay. Since then, he expressed with great kindness by email his willingness to participate in activities with the philosophical community of our country. Sadly, this opportunity never materialized as we were waiting for his next holidays here. It would have been a great honor for us to welcome a professional of his talent and career.

    The teachers of the Department of Logic and Philosophy of Logic (Universidad de la República, Uruguay) extend our condolences to Horacio Arló Costa´s family and to his colleagues and students at Carnergie Mellon University.

    José Seoane and Fernanda Pallares

  36. […] have words of remembrance, please feel welcome to post them at Choice and Inference under the entry In Memory of Horacio Arló-Costa, as we will, with your permission, use your words of remembrance for the […]

  37. Nicole Hassoun says:

    Writing from Finland it is hard to imagine what it feels like in Pittsburgh without Horacio. It is hard even to say that his office was next to mine, because it feels like he should still there. But when we were both working late, his company transformed what would otherwise have been many lonely evenings into opportunities for good conversation and friendship. I will miss talking to him about everything from aesthetics and global economics to experimental philosophy and epistemology. Horacio was a kind and generous man who knew a lot about what is important in life.

  38. […] have words of remembrance, please feel welcome to post them at Choice and Inference under the entry In Memory of Horacio Arlo-Costa, as we will, with your permission, use your words of remembrance for the volume. Please send all […]

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