Flavia Marcacci | Professor of History of Scientific Thought, Pontifical Lateran University, Rome, Italy

Beyond Galileo: facts, values, and historical joints

What greater honour could there be than to share some reflections at such an important forum to foster the encounter and integration of science and religion? Our former Chancellor Sánchez Sorondo’s 80th birthday is a formal occasion, a particularly happy one because his career is synonymous with attention and dedication to philosophy. Philosophy is precisely the kind of knowledge that, better than any other, can outline questions and form categories that relate to science and religion. Chancellor Sánchez Sorondo was responsible for first defining the fundamental issues in this debate during his years at Pontifical Lateran University, where he was Professor of History of Philosophy from 1976 to 1998 and even Dean three times. Bishop Sánchez Sorondo has strenuously worked on healing fragmentations, seeking unity, and establishing the dialogue between philosophical disciplines and other forms of knowledge. More specifically, he has cultivated the relationship between philosophy and science, forging concepts and contexts useful for harmonizing seemingly different sensibilities.

Three questions are central to our plenary session:

  1. What are new and emerging breakthroughs in sciences?
  2. How have scientific breakthroughs come about?
  3. How can they influence new, better, and more effective ways to reduce problems threatening people, peace, and the planet?

These are questions of considerable complexity because they open up profound epistemological issues. I have been asked to refer to one of the best-known Italians of all time, the great Galileo Galilei. I will humbly try to ensure that the figure of Galileo and his role in the development of philosophical and scientific thought can provide some insights to answer these questions.

1. The emerging new science at a historical turning-point

Modern science was born between the metaphor of the organism and the metaphor of the machine, inheriting the rich sensibility of the Renaissance: on the one hand, a passionate focus on naturalistic observation; on the other, a profound reworking of the mathematical tradition that reinforced astronomical knowledge. The spirit of renewal mingled with the use of established knowledge. The organization of new forms of Scientia was a slow and complex process that took root in the context of profound social changes. The universe’s dimensions expanded thanks to new instruments, and nature revealed its most intimate structures. New cultural milieus arose, and philosophers and men of letters found in the academies new centers in which to engage in a mutual dialogue. This and much more took place while the Thirty Years’ War was raging: new balances were established in Europe with the Peace of Westphalia (1648), while the New World continued to prompt further explorations and conquests across the ocean. The complexity and stratification of the cultural and social processes between the mid-fifteenth and the seventeenth century are reminiscent of what is happening today, noticeable differences notwithstanding. In many respects, we are living in a revolutionary era like Renaissance today. The urgencies related to the protection of the planet and energy management, migration, the swift circulation of information, and the new relationship between digital communication and politics are just some of the challenges that characterize our time, and which force us to realize that old interpretative categories are unable to explain the present. Valuing the potential of novelties rather above the difficulties posed by transformation is an attitude that can make our time an epochal moment of transition (bringing about an epochal change, and not a change of era, as Pope Francis says, Evangelii gaudium 52[1]), such as to leave a distinct and positive conceptual and material legacy.

Galileo lived in the context of a real change of epoch. In this context, he acted as the interpreter, promoter, and prophet of a more delimited and specific yet no less revolutionary change than the political changes taking place: the transformation of the old natural philosophy and the change associated with the new sciences. Many of Galileo’s discoveries would deserve a Nobel Prize today: the use of the telescope to observe the heavens, the earthy nature of the Moon’s surface, Jupiter’s satellites, the observation of countless stars, Saturn’s rings, sunspots, the law of the pendulum, the law of the falling bodies, and a partial understanding of the principle of relativity. One might discuss, for instance, what scientific prize Galileo’s studies on the resistance of materials would merit today, or his intuition of the principle of inertia, even if this principle remained incomplete. It would also be necessary to invent a philosophical prize for the acute epistemological intuitions that stand out in The Assayer, a landmark work published exactly 400 years ago; a literary prize for the luminous prose in the Italian vernacular – of the sort that Italo Calvino[2] famously sought to award Galileo – would not be excessive. I leave it up to theologians to judge whether Galileo deserves a theological prize for his ability to identify methodological questions that even the Galileo Commission recognized when it reviewed certain aspects of the Galileo affair between 1981 and 1992.

The intuition of novelties is one thing, their systematic development quite another. Galileo could not fully organize all his knowledge, but he is not to be blamed for this. Even a genius needs a scientific community to help him codify and frame the content and consequences of each discovery: to do so, he would have had to wait for an established tradition of shared scientific research. Thus, we come to our first question: What are these new breakthroughs in sciences? Galileo brought many breakthroughs to science, including the just mentioned ones. We must acknowledge, however, that we need a definition of ‘new’. If there is something ‘new’, there must also be something ‘old’. In order to decide that a fact is new, we need to understand what an old fact is: a fact is old when it is known and explained by previous categories, perhaps still in use. Considering the most recent studies, we should make an initial distinction.[3] There are novelties obtained by looking for something that has been posited within a theory but has not yet been found, as recently it happened with Einstein’s gravitational waves. In that case, we speak of prediction. Then there are some novelties which are neither sought nor supposed, unusual facts that are initially difficult to identify, as in the well-known case of Wilhelm Conrad Röntgen: a specific form of serendipity which is not entirely coincidental, as it occurs within scientific studies and experiments.[4] This distinction impacts any generic definition of science, as in both cases, it is connected with scientific work practices and the nature of scientific knowledge.

2. Evolutive thinking

How did scientific breakthroughs come about? This is the second question we are investigating in our Plenary Session. How does science change, how does new knowledge emerge? What determines the turning points in science? Galileo’s story is a notable one because politico-theological, scientific, and ontological problems are intertwined in his life and career.[5] One refers to the other, as typically in epochal changes. Conceptual boundaries can only exist when the questions and the logical and material tools to seek answers have become clear. Until this happens, there is a tension between the desire to understand and the realization that questions are reducible to doubts and uncertainties.

A range of issues marks Galileo’s life, making it an emblematic case study of interrelationships between science, philosophy, and religion. Among the many politico-theological problems faced by Galileo, the most obvious one is the controversy with the Church: it must be recalled that Galileo abjured and remained a Catholic without abandoning his scientific convictions. He was aware that his writings were becoming popular in Northern Europe, and he was happy about this. About the scientific discoveries and problems addressed by Galileo, they were innumerable, and I have only listed some of them, although not exhaustively. Concerning those problems that we define as ‘ontological’ and relating to the nature of entities, we need only refer to the discussions and research on the nature of celestial bodies such as the Moon, already found in Sidereus nuncius (1610), the question of corpuscolarism, and the issue of the nature of light, which later in Galileo’s career involved him in a dispute with the physician Fortunio Liceti (1640). Such ‘ontological’ problems are rooted in epistemological issues. I would like to return to The Assayer. This masterpiece is widely known as a treatise on the scientific method and as an exemplar of rhetoric and scientific communication. Indeed, the text is full of passages that go in this direction. Galileo devised these argumentative stratagems for the real purpose of the work: weakening the arguments for geocentrism, including those by Tycho Brahe’s epigones. The end justifies the means, and the means Galileo used were both experimental and conceptual. By relying only on the former, unfortunately, it was not easy to compete and win in the controversy because the Tycho-centrists also knew and used the same data and observations. It was therefore necessary for Galileo to refine his conceptual tools. Of course, this was a challenging task because changing concepts, categories, structures, and demonstrative techniques was, in some respects, more difficult than finding the stellar parallax with the inadequate instruments of the time. Galileo nevertheless attempted this strategy and set science on a path of innovation that made his revolution something more than a revolution in science: it made it an intellectual revolution.[6]

The philosophy of science developed over the last hundred years has sought to address the question of why science changes. Many answers have been devised, perhaps the best known being that by Thomas Kuhn, who identified both empirical and social reasons for scientific preservation or change.[7] The Kuhnian jargon, based on expressions such as paradigms, meaning variance, puzzle, normal science, and revolutionary science, is so well known that there is no need to discuss it here. Science as a collective enterprise had already been noted by Ludwig Fleck, who had spoken of ‘thought collectives’ (Denkkollektiv).[8] After Kuhn, Imre Lakatos sought new ways to integrate this historical approach with rationality criteria to explain the change in scientific theories.[9] More recently, this perspective has been updated by recognizing that science is the enterprise of a varied community, which also includes women (the great absentees in the history of science, and undoubtedly not due to any scientific demerits on their part), people of different social and geopolitical origins, and scholars with different cultural and personal backgrounds.

Data and observations are crucial factors in the crisis of a scientific theory when they bring out new facts. Nevertheless, a scientific crisis does not depend on facts alone. It depends on how the facts manifest themselves to the sophisticated experience of the scientist. Novelties are perceived as such because the old categories prove inadequate to understand them. It is therefore imperative to examine the logical, conceptual, and epistemological content inherent in a scientific theory if one wishes to understand it. We can generically conclude that between the input data and observations relating to a phenomenon and their conceptual explanation, there is a hypothetical outcome that is the compromise between what one already knows and what one expects to know. Each hypothesis is then further corroborated, refined, refuted. “One knows what one learns”, said Aristotle (An. Post. I 1 71b5-7). So, we come to the third question.

3.     With and beyond Galileo: curiosity-driven science

I have just quoted Aristotle. Bishop Marcelo Sánchez Sorondo is a philosopher who has long dealt with the classics of philosophy, primarily Aristotle. In 1993, he edited and presented a volume of contributions by professors from the lively philosophy faculty of the Pontifical Lateran University, where he was Dean.[10] Msgr. Sánchez Sorondo urged an engagement with the Stagirite’s thought and with the Greek view of nature in general. Note the continuity with the concept of this lecture, which recalls Aristotle’s words at the beginning of Book A of the Metaphysics (A.982 b 11-20):

Now he who wonders and is perplexed feels that he is ignorant (…); therefore, if it was to escape ignorance that men studied philosophy, it is obvious that they pursued science for the sake of knowledge and not for any practical utility.

Wonder drives knowledge, an assumption already found in Plato. This view of human knowledge was later complemented by Thomas Aquinas, who recognized the mediated character of our knowledge: this mediation occurs through the human being standing in front of the object he has to study. “Unde hoc non est demonstratio sed suppositio quaedam” (Thomas Aquinas, In I De coelo et mundo I 1 num. 28): these are very relevant words when read from the perspective I am outlining. Scientific theories proceed via hypotheses and experiments, from one vital aspect to another, so knowledge is never definitive. What Aquinas could certainly not say when referring to science is that scientific knowledge is always due to a community of cooperating scientists: even if some discoveries are attributed to individual scientists, the latter always implement what they inherit from past scientists and what is verified by scientists of the present and future.

Behind all great scientific discoveries lies this drive to know, fuelled by wonder and curiosity. The hypothetical dimension of scientific research moves us from enquiry to enquiry. A scientist’s mind may rest after years of work, but a new generation of scientists will ask new questions. Galileo’s curiosity was accompanied by the libertas philosophandi, which was instrumental in producing new ways of thinking. Only after their emergence can we speak of new systems of thought. But at that point, it is legitimate to ask what consequences they bring. When we speak of the consequences of science, the first defendant is technology. If we only think of Galileo, we realize that, on the one hand, he was busy studying kinematics, mechanics, astronomy, and material sciences. He advanced in his studies because he was not detached from the use of instruments: from the balance for statics problems to the telescope and the microscope – which he perfected – and the geometric-military compass. After him, the link between science and technology grew stronger and stronger, and it became increasingly evident that science and technology modify society. Thinkers like Hans Jonas reflected extensively on this topic, linking technical applications and the exercise of freedom.[11] This reveals the deeper link between curiosity and freedom, raising the question of whether freedom is an end in itself or whether it should always be directed towards some goal. The curiosity that drives scientists to learn about nature can help penetrate the mystery of human beings and creation, far from being a vicious movement of intelligence.

Here we come to the last question of the plenary session: how can scientific breakthroughs influence new, better and more effective ways to reduce threats and problems for people, peace, and the planet? Let’s start from people. What is the link between scientific breakthroughs and respect for the human person? “Realities are greater than ideas” (Pope Francis, EG 231). Science is the speculative journey that teaches to ponder things, compare ideas with reality data, activate synergies and collaborations between scholars, question assumptions, expose errors, come to terms with uncertainty, evaluate methods and trust the resolutions they lead to. Here I would refer to the history of science in the 20th century, which saw the emergence of new theories and gave rise to those sciences we have seen discussed over the last few days. Science teaches humility, the most important of virtues for the growth of knowledge. However, it can only do so when it becomes aware of its history and epistemological foundations. Without this critical awareness, any scientist can become arrogant, if she forgets that scientific theories are the complex product of achievements and defeats, contradictions, win-wins, and paradoxes. The kind of humility that a self-aware science teaches is the ability of a discipline to question itself and remain open and adaptable, without falling into the abyss of absolutism and relativism. This scientific lesson should be taught to women and men of all ages.

As for peace, its relationship with science has been widely discussed, by influential scholars, especially on the historical level. In 1955, Albert Einstein and Bertrand Russell published the Manifesto for Peace, which inspired the Pugwash movement for disarmament and peace[12] at the end of last century. The importance of political engagement as a way to make both the scientific world and public opinion aware of new approaches to international security in the atomic age is evident. This is a sadly topical and urgent issue even now. From the post-World War II period to the present day, countless documents and political activities have directly involved scientists. “There is before us, if we choose, a continuous progress in happiness, knowledge and wisdom. Would we, instead, choose death, because we cannot forget our contentions?”, wrote Russell.[13] Rather than discussing physics for peace, mathematics for peace, economics for peace, and so on, we should talk about those women and men who practice science and find opportunities to reflect and promote peace. Their interaction and collaboration are the first sign of peace building.

Finally, we come to the planet, our Common Home. Science makes possible technologies and vice-versa. In the face of today’s environmental disasters, it is clear that this mutual dependence has not always been well-assessed. Indeed, we often speak of sustainable development, a concept distinct from sustainability. The latter refers to a balance between the environment, living species, and human actions, whereby the ecosystem is respected and does not suffer devastating shocks. On the other hand, sustainable development identifies that set of practices that can be pursued in the socio-political, economic, and scientific-technological spheres to achieve sustainability. For development to be sustainable, adequate cultural action is key, as a means to promote good practices but also as a correct way of understanding the continuity between human beings and the environment.

4. Conclusion: Veritas as Gaudium

Galileo’s question is helpful to point out the need to discuss the integration of science and religion as pieces of knowledge. There is an urgent need to do more than just note the degree of personal integration between the two in a scientist’s life. Even a dialogical approach or cross-fertilization to enrich discussion would not be sufficient. The purpose of this discussion is not only to engage in dialogue but to find methods and categories to develop a systematic and rigorous integration.

The PAS Plenary Sessions offer new narratives within which experts and practitioners can shape the collective vision of science in a way that respects the results of scientific research and the philosophical inquiry on science. Events such as this are most valuable when an anti-scientific spirit exists and is widespread and a clear signal is to be given: any cultural proposal must take science and all its results into close consideration. These narratives can become a common value, helping to understand science and its effects on political decisions and social customs, promoting its most edifying aspects.

Bernard de Fontenelle lamented the drudgery of the physical and mathematical sciences, but recalled that in Homer’s time, it was a source of great wonder that a man could subject speech to a rhythm and measure. Fontenelle hoped that the scholars of his time would be remembered as the creators of great wonders.[14]

Thus, let me conclude by mentioning two key points that we must bear in mind for future generations’ sake: the first is achieving a credible synthesis capable of harmonizing the contribution of science and its rigour with categories comprehensible to non-scientists and respectful of our Common Home.

The second key point is that there is more to knowledge than just effort and dedication: knowledge must lead to joy, and scientia does not rhyme with tristitia.[15] Gaudium is the measure of veritas itself. Awareness of the processuality and gradualness of the development of the scientific knowledge, the ability to share this knowledge with others, the possibility of making it an instrument for common growth, and the continual amazement at the fact that nature is given to human beings to be progressively understood via a collective effort that calls for humility and the sharing of satisfaction. All these aspects are embedded in a new style of reasoning that science is teaching today. So, science can indicate a style of knowledge, sharing, and learning that is very close to the recent criteria for the renewal of Church teachings. (Veritatis Gaudium 4). This style opens not only the mind but also the heart to joy since joy is what characterizes the Truth (Veritatis Gaudium 1). Furthermore, only that which gives joy can claim to be a timid reflection of a Truth that goes beyond us, to unite us.


[1] “We are not living an epoch of change so much as an epochal change” (Pope Francis, Address for the Meeting with the participants in the fifth Convention of the Italian Church, November 10, 2015, available at the URL: https://www.vatican.va/content/francesco/en/speeches/2015/november/documents/papa-francesco_20151110_firenze-convegno-chiesa-italiana.html).

[2] I. Calvino replied to the writer Anna Maria Ortese by appealing to Galileo as “the greatest writer of Italian literature of any century” in a letter published in the Corriere della Sera on December 24, 1967.

[3] Only two references for a very complex debate: Zahar, E.G. (2001). The interdependence of the core, the heuristic and the novelty of facts in Lakatos’s MSRP. Theoria: An International Journal for Theory, History and Foundations of Science, 16(3(42)), 415–435; Worrall, J. [2010]: ‘Error, Tests, and Theory Confirmation’, in D.G. Mayo and A. Spanos (eds), Error and Inference: Recent Exchanges on Experimental Reasoning, Reliability, and the Objectivity and Rationality of Science, Cambridge: Cambridge University Press, pp. 125-54.

[4] W. Bynum, “Radioactivity”, in A Little History of Science, Yale University Press, New Heaven-London, 2012, pp. 189-195.

[5] Allow to refer to the mine Galileo Galilei, una storia da osservare, Lateran University Press.

[6] W. Shea, Galileo’s Intellectual Revolution, London: McMillan 1972.

[7] T. Kuhn, The Structure of Scientific Revolution, Chicago: University of Chicago Press (1st ed. 1962).

[8] L. Fleck, Genesis and Development of a Scientific Fact, Chicago: University of Chicago Press, 1979 (1st English translation).

[9] I. Lakatos, “Falsification and the Methodology of Scientific Research Programmes”, in I. Lakatos, A. Musgrave, Criticism and the Growth of Knowledge, Cambridge: Cambridge University Press 1970, 91-196.

[10] M. Sánchez Sorondo, Physica, cosmologia, naturphilosophie. Nuovi approcci, Roma: Herder-Università Lateranense, 1993.

[11] Hans Jonas, The Imperative of Responsibility. In Search of an Ethics for the Technological Age, Chicago: University of Chicago Press, 1984.

[12] The text of the Manifesto Russell-Einstein is available at  https://pugwash.org/1955/07/09/statement-manifesto/

[13] B. Russell, Man’s Peril from the Hydrogen Bomb, The Listener, no. 52, 30 December 1954, 135-6.

[14] B. de Fontenelle, Poésies pastorales de Monsieur de Fontenelle. Avec un traité sur la nature de l’églogue, et une digression sur les anciens et les modernes, Michel Guerout, Paris 1688.

[15] F. Marcacci, Gaudium aude! “Fides et Ratio” venti anni dopo come metodo per la ricerca nelle università, in Lateranum LXXXV/1, 2019, 171-187.