Thursday, March 30, 2017

The Great Myths 3: Giordano Bruno was a Martyr for Science

Ettore Ferrari's 1889 monument, on the site of Bruno's execution in the Campo de'Fiori, Rome 
Last month the Italian National Association of Free Thought gathered in the Campo de'Fiori in Rome to commemorate the 417th anniversary of the execution by burning at the stake of Giordano Bruno on that spot on February 17, 1600. The ceremony highlighted Bruno as a free-thinker who ran afoul of dogmatic religious beliefs. But he was also remembered by others as a scientist who died because his rational thought contradicted the superstition of his day and a symbol of an eternal struggle between science and religion and Bruno is thus regularly invoked by New Atheists as a primary example of the old Conflict Thesis they love so much.  

So the Atheists Against Pseudoscientific Nonsense group on Facebook solemnly remembered Bruno's fiery death with this meme:



Thus they presented Bruno as a rational scientific thinker who held the idea that the stars were suns that had their own potentially-inhabited planets and who rejected the doctrine of Transubstantiation, all for scientific reasons, and so died a martyr for science.  But while this group's fight against pseudo science is admirable, their perpetuation of New Atheist pseudo history is not.


Bruno the Mystic

To begin with, any knowledge of Bruno that goes beyond internet memes will make the idea that he was in any sense of the word a "scientist" immediately dubious.  Bruno was a brilliant and eclectic thinker who ranged over a number of the disciplines of his day, and so is difficult to put into any one category.  He was a metaphysicist, a magus, an expert in mnemonics, a neo-Pythagorean, a neo-Platonist and an astrologer.  He advocated a kind of philosophical reasoning, but it was one focused on images and symbols and the use of visualisations and metaphors.  He had a cosmology that included the physical universe, but he rejected the use of mathematics to explore it, considering that too limiting and preferring what he believed was his own intuitive sense for symbols, sacred geometries and what simply felt right.  His eccentric melange of ideas included things like Copernicus' heliocentrism and Nicholas of Cusa's centreless infinite universe, but it also included magic, stars and planets with animating souls, ancient Egyptian religion and Pythagorean symbolism.  Probably the best word to describe him in modern terms is to say he was a "mystic".

Some who are at least partially aware of all this have tried to argue that no-one in this period was a pure scientist and that most of the great scientists of the time not only held views that were distinctly mystical but were also directly motivated by them.  After all, Galileo was a working astrologer, as this was his primary function at the court of the Duke of Florence, and all evidence indicates he, like his contemporary astronomers, fully accepted astrology. Kepler's discoveries were motivated by his determined belief that the structure of the cosmos was literally based on the five Platonic Solids and their mystical connection to the classical elements of earth, water, air, fire and quintessence. And it's now becoming much better understood that Newton spent far more time on alchemy and the calculation of the date of the Apocalypse than on anything for which he is celebrated today.  So, it's argued, is Bruno really any different to these giants of early science in his acceptance of mysticism ?

Unfortunately, the answer is "yes".    

The difference is that while these others certainly accepted ideas that we consider totally unscientific and were even motivated by them to do empirical science, they actually did do empirical science as we know it.  And Bruno did not.  Kepler's animating belief in the intrinsic importance of the Platonic Solids was completely wrong, but his drive to establish this idea through observation and mathematics led to his Three Laws of Planetary Motion and these were not vague mystical intuitions, they were observed, measured and repeatable real world constants.  They were real science.  Newton may have spent long hours coming up with his theological calculation that, according to his readings of the books of Daniel and Revelation, the world could not end before 2060.  But he also set down the principles of celestial mechanics and gravitation in his Principia which revolutionised science and can be confirmed and utilised to this day.  Bruno did nothing like these things.

On the contrary, Bruno scorned empiricism and rejected mathematics as a way of understanding the world.  As Hilary Gatti puts it, he had "a well-known and clearly expressed distaste for the new mathematics, which he saw as a schematic abstraction attempting to imprison the vital vicissitudes of matter into static formulae of universal validity." (Hilary Gatti, Giordano Bruno and Renaissance Science, Cornell, 2002, p. 3)   Far from joining his contemporaries in adopting what was to become the classic scientific method, Bruno used mystical intuition, coming to findings "reached through a process of logical-philosophical reasoning with a marked bias toward vizualization through images and symbols rather than through experiment or observation." (Gatti, p. 3)

This meant not only did he not join what we can call the Scientific Revolution of his period, he actively rejected its methods, even though he accepted a few of its findings.  This acceptance was not based on any deep understanding of science - his treatment of Copernicanism in his Ash Wednesday Supper dialogue (1584) shows that his grasp of the actual details ranged from shaky to dead wrong  - but on the fact some of them fitted his mystical cosmology.  He accepted science only when it suited his non-scientific ideas.

So in the Ash Wednesday Supper he has his surrogate figure "Theophilus" begin by praising Copernicus for being "possessed of a grave, elaborate, careful, and mature mind; a man who was not inferior, except by succession of place and time, to any astronomer who had been before him".  But he then quickly turns to downplaying Copernicus' status, adding "[b]ut for all that he did not move too much beyond [earlier astronomers]; being more intent on the study of mathematics than of nature" and then damning with faint praise Copernicus' "more mathematical than physical discourse".  All this is simply a prologue for Theophilus' lengthy praise of "the Nolan" (i.e. Bruno himself) as, among many other great things "the one who found again the way to scale the skies, to make a tour of the spheres, of the planets, and leave behind the convex surface of the firmament" and who "set free the human spirit and cognition which was retained in the narrow prison of the turbulent [earthly] air, from where as if through some holes it could contemplate the most distant stars".  And who did so without being constrained by mere observation, mathematics and actual science.

So because Copernicus' idea that the earth was not the centre of the cosmos suited his mystical view of an unbounded universe, he accepted the scientific conclusion while scorning the science that underpinned it.  But when science didn't fit his views, he rejected it wholesale.  In his De immenso he came up against the problem that the planets did not actually move the way his mystical vision said they should.  But he just brushed this aside with a blithe assurance to his readers that “the geometers” would eventually realise that he was right.  They didn't.

So this is not someone like Kepler or Newton, who believed and practised mysticism while also doing science.  This is someone who accepted scientific ideas when they suited his mysticism, rejected them when they didn't and who did no science at all.  Frances Yates in her influential Giordano Bruno and the Hermetic Tradition (University of Chicago, 1964)
dismissed the idea that Bruno had any connection to the "new science" of his day at all, placing his mystical philosophy firmly in the context of the writings of "Hermes Trismegistus " and garbled ideas about ancient Egyptian religion based on them.  More recent writers like Hilary Gatti believe this goes too far and that Bruno was at least tangentially related to the science of his day.  But that he was not, in any sense, a scientist:
In Bruno’s time, the word “science” was not yet common coin, and it would start to be used in the restricted sense we know today only by later figures such as Galileo. Bruno would still have thought of himself as a natural philosopher and of sciences as scienza, knowledge of any kind. Even so, natural philosophers of the period such as Paracelsus, Johannes Kepler, Tycho Brahe, William Gilbert, William Harvey, and later Galileo and Francis Bacon, can be thought of as also practitioners of the new science, actively involved in more or less methodical research into natural causes and effects. Not everybody would agree that Bacon fits into that category. Certainly Bruno does not. He never made an astronomical observation of his own." (Gatti,  pp. 2-3.)
 If there is a modern figure who can be said to be analogous to Bruno, the one who fits best would be someone like Deepak Chopra. New Agers like Chopra infuriate actual scientists when he invokes ideas like quantum mechanics and genetics to prop up his mystical ideas about how consciousness "creates reality".  Like Bruno, Chopra and his ilk praise science up to the point where it can be made to fit their mysticism, but then reject it when it does not.  And they talk down to scientists, depicting them as "limited" by their devotion to empiricism and experiment.  The gap between true science and the kind of intuitive opining of mystics like Bruno and Chopra was not as defined in the late sixteenth century as it was now, but even then it was becoming clear enough - Galileo had no time for Bruno's woolly conjectures.  What is deeply ironic, however, is atheists and sceptics today who would regard Chopra as an unscientific idiot, holding Bruno up as some kind of scientific martyr.
Bruno before the Inquisition - a relief from the  Campo de'Fiori monument


What Were the Charges Exactly?

Despite the fact that he can't be called a scientist and nothing he did was remotely like science (even by sixteenth century standards), New Atheist pseudo history desperately needs Bruno to be a martyr for science, because without him the whole "Christianity suppressed science" dogma has no martyrs at all.  If Bruno was not a scientist executed for doing science or holding scientific views, then all the New Atheist version of the Conflict Thesis has is the Galileo Affair, and just a little bit of exploration of that quickly indicates that it was not the "science versus religion" fable of popular belief.

So when the Neil deGrasse Tyson TV reboot of Cosmos went to air in 2014 and began with a highly garbled version of the Bruno story, many New Atheist luminaries were not happy at those pesky historians who noted its errors and misrepresentations.  As I detail at length elsewhere (see "Cartoons and Fables - How Cosmos Got the Story of Bruno Wrong"), the new Cosmos series went out of its way to present Bruno as a brave innovator who was crushed by fundamentalists.  Its writers were careful to note that he was not a scientist, but their version of the story was still riddled with mistakes and distortions of history and this was noted by many historians and commentators at the time.  And people like PZ Myers, one of the grumpiest uncles of New Atheism, were not going to let things like objective historical analysis get in the way of their belief in pseudo historical myths. When both Peter Hess and Josh Rosenau of the National Center for Science and Education took issue with the program's depiction of Bruno, Myers rent his garments and howled "Apologism!" (which is the New Atheist equivalent of "Heretic!").  In a rant that displayed a spectacularly weak grasp of any relevant history, Myers thundered to the choir:
"Whenever I see one of these guys throw out noise like 'a nuanced and sophisticated understanding of the long, rich, and complex relationship between religion and the sciences', I want to ask…what was nuanced and sophisticated about setting a human being on fire?"("Missing the point of Giordano Bruno")

Which kind of "misses the point" that, as discussed above, the mystic Bruno his ideas and therefore his execution had nothing at all to do with science in the first place.

The "martyr for science" myth depends on the idea that Bruno was condemned and burned for holding scientific ideas about the cosmos: namely, that the earth went around the sun and that there was an infinite number of worlds, with the stars as other suns possibly circled by inhabited worlds.  Since we know both these things to be correct and to be wholly scientifically based, it seems to follow for many people that, therefore, Bruno was persecuted and killed for science.

Part of the problem here is that we don't actually have the charges made against Bruno, because they were among the many Vatican documents lost when Napoleon carted most of the Papal archives to Paris between 1810 and 1813.  What we do have are records of what Bruno was questioned about in his earlier trials before the Venetian Inquisition in 1591. And we have a summary of his trial in Rome, which also indicates what he was questioned about. These topics include a grab bag of heretical theological ideas, including denying the virginity of the Virgin Mary, declaring Jesus to have been a magician, denying the Trinity and denying Transubstantiation.  He was certainly questioned about his heliocentric cosmology and his ideas about the infinity of worlds, but we don't have the final charges against him or the final eight statements that he was ordered to reject in his trial in Rome.  

Grumpy uncle PZ Myers, however, seems to think we do.  With great fanfare in yet another rant about the Cosmos episode he declares this in no uncertain terms:
 But also, I’m getting a little annoyed with these people claiming that Bruno wasn’t killed for that one specific belief about the movement of the earth. He was! We have the list of eight charges for which Bruno was condemned. Note especially number 5. 
1 – The statement of “two real and eternal principles of existence: the soul of the world and the original matter from which beings are derived”. 
2 – The doctrine of the infinite universe and infinite worlds in conflict with the idea of Creation: “He who denies the infinite effect denies the infinite power”. 
3 – The idea that every reality resides in the eternal and infinite soul of the world, including the body: “There is no reality that is not accompanied by a spirit and an intelligence”. 
4 – The argument according to which “there is no transformation in the substance”, since the substance is eternal and generates nothing, but transforms. 
5 – The idea of terrestrial movement, which according to Bruno, did not oppose the Holy Scriptures, which were popularised for the faithful and did not apply to scientists. 
6 – The designation of stars as “messengers and interpreters of the ways of God”. 
7 – The allocation of a “both sensory and intellectual” soul to earth. 
8 – The opposition to the doctrine of St Thomas on the soul, the spiritual reality held captive in the body and not considered as the form of the human body. 
("Still picking nits over Giordano Bruno")
So if we do have this perfectly clear list of beliefs that Bruno refused to abjure, why do competent historians like Hilary Gatti and Joel Shackelford keep saying we don't know exactly what ideas he was condemned over?  Are they just incompetent idiots?  Or has PZ Myers, an associate professor of biology at a public liberal arts college, made a remarkable discovery of a document unknown to all historians of science?

Well, it's neither.  Myers, in his total historical incompetence, simply did a Google search and turned up this rather amateurish website of resources on the trial of Bruno.  It was put together by one Lawrence MacLachlan, who apparently is or was "Director of Research & Instructional Services" at the University of Missouri-Kansas' law library.  Exactly where MacLachlan got this list is unclear.  It contains quotes and commentary, but where the quotes come from and who the commentary is by is unknown. The quotes don't seem to be from Bruno's works and searches on the commentary or even on the commentary and quotes simply leads back to the University of Missouri-Kansas page or to blogs and forum posts that are clearly cutting and pasting from it.  So Myers simply found something that suited him, didn't bother to check it and presented it as historical evidence. Which is yet more evidence that, when it comes to history, most scientists should just stick to science.

Of course, the reason the clueless Myers seized on this dubious list so uncritically is that it seems to confirm the idea that scientific views were among the reasons Bruno was executed.  He garrumphs that the other items on it are "mostly a lot of New Agey sounding bollocks" (which is one way to summarise the whole of Bruno's cosmology I suppose), but leaps with glee on the claim that "the [idea that] earth rotates around the sun was one of his beliefs" and that he was killed for this according to the unsourced list he found lying around on the internet.

But is there any real evidence for this?  

The records of his trial in Venice show that he was certainly questioned about his heliocentrism.  He was questioned about many things, including where he went and when and even what clothes he was wearing at the time, so it's hardly surprising that his unusual advocacy of what was then very much a fringe scientific theory rejected by almost all astronomers would have attracted some attention.  But was this one of the eight items that he refused to reject and ultimately got him killed?

It seems it wasn't.

This is because of the way the Roman Inquisition operated.  As Thomas F. Mayer  details in his careful historical analysis of the workings of the Roman Inquisition, (see The Roman Inquisition: A Papal Bureaucracy and Its Laws in the Age of Galileo, University of Pennsylvania Press, 2013, p.152, 169 and extensively elsewhere), the Inquisition was a highly rule-bound institution that worked “not just by precedent but also by case law” (p. 162).  This meant that it consulted two sources before going to the (considerable) effort of making a ruling on whether or not something was heretical: (i) it consulted canon law back to its beginnings in the tenth century and (ii) it consulted its own previous rulings.  This means that if Bruno had been condemned for heliocentrism in 1599 it would be because heliocentrism had been ruled as being contrary to scripture and therefore at least formally heretical.

But this poses a problem for anyone wanting to claim Bruno was condemned for proposing a heliocentric cosmos.  If the Roman Inquisition had ruled this was formally heretical in 1599, why did Cardinal Bellarmine put the question to assessment during Galileo's later trial in 1616?  Not only would the precedent ruling have been there from just 17 years earlier, but Bellarmine himself had prosecuted Bruno's trial.  After all, this was what happened in 1633 when Galileo came before the Inquisition again - they referred to the 1616 precedent.  So did Bellarmine simply forget all about the Bruno trial?

The only logical conclusion is that Bellarmine put the issue of heliocentrism to assessment in 1616, because there had been no formal ruling on it in 1599.  Bruno had clearly been questioned about it in relation to his many other weird and radical ideas, but it was obviously not one of the things he had been condemned for, or this would have set a legal precedent to be used in 1616.

So, despite what PZ Myers would like to believe, heliocentrism does not seem to have been among the reasons Bruno was executed.  Then again, Myers seems prepared to believe any number of pseudo historical myths about science being persecuted by religion and in his "Missing the Point" post manages to rehearse some classic New Atheist bad history.  This includes the myth that Copernicus delayed publication of his book "out of fear [of the Church]", despite the fact that he had been patronised and encouraged by his local bishop, a prominent Cardinal and Pope Clement VII himself.  Myers also dismisses Tycho Brahe as "a geocentrist", ignoring the fact that his geoheliocentrism was a purely scientific position that had nothing to do with religious dogma.  And, bizarrely, he throws in the fact that Kepler's mother was accused of witchcraft, though without explaining how this is relevant to anything at all.  Yet again, we find a New Atheist who, as a historian, makes a great biologist.


Multiple Worlds

So not only did Bruno not hold a heliocentric view for any scientific reason, but his heliocentrism was not even one of the reasons he was condemned and executed.  Denial of the doctrine of Transubstantiation in the Catholic Mass was a repeated accusation made against him in both his Venetian and Roman trials, though he can't be said to have denied that idea for any scientific reasons either; that was a purely theological position.  Similarly we find repeated accusations that he denied the virginity of Mary, denied the Incarnation of Jesus and doubted the doctrine of the Trinity - all heretical positions for any Catholic in 1599.

And we do have what seems to be an eye witness to his condemnation and execution who lists all these accusations as being among the reasons for his death.  Gaspar Schoppe was a twenty-four year old humanist scholar from Germany who had converted from Lutheranism to Catholicism and so became favoured by Pope Clement VIII as a tool in the Counter Reformation.  In February 1600 Schoppe was living in the palace of Cardinal Ludovico Madruzzi, where the final condemnation and sentencing of Bruno took place on February 8 1600.  Schoppe was keen to distance his former Lutheran friends from the ideas of Bruno, who he calls "a monster", and he includes all the "heretical" theological ideas mentioned above as among the reasons Bruno was executed.  But the first thing he mentions is the idea that "Mundos esse innumerabiles" - i.e. "that worlds are innumerable".

Bruno's idea of an infinite universe with the stars as suns and multiple worlds is, after his heliocentrism, the one that gets New Atheists most excited and leads them to pretend that he was a scientist burned for this very scientific conception.  Historians, on the other hand, have long been unconvinced that this "multiplicity of worlds" was a reason for his condemnation at all.

In her seminal work on Bruno as a Hermetical magician, Frances Yates wrote "the legend that Bruno was prosecuted as a philosophical thinker, was burned for his daring views on innumerable worlds or on the movement of the Earth, can no longer stand." (Giordano Bruno and the Hermetic Tradition, p. 355).  Likewise,  Steven J. Dick writes: "It is true that he [Bruno] was burned at the stake in Rome in 1600, but the church authorities were almost certainly more distressed at his denial of Christ’s divinity and alleged diabolism than his cosmological doctrines." (Plurality of Words: The Extraterrestrial Life Debate from Democritus to Kant, Cambridge University Press, 1982, p. 10 - though Dick seems to have modified his view since).  And Michael J. Crowe comes to the same conclusion that it is a myth "that Giordano Bruno was martyred for his pluralistic convictions’ about many worlds." (The Extraterrestrial Life Debate 1750-1900: The Idea of a Plurality of Worlds from Kant to Lowell, Cambridge University Press, 2011, p. 8).  

And this has been seen as a reasonable conclusion.  As Yates notes the surviving summary of his trial "shows how little attention was paid to philosophical or scientific questions in the interrogations" (p.355) and the whole idea of the stars as suns and multiple worlds that may even be inhabited was not even one Bruno came up with.  As he himself says, just as he got the idea of heliocentrism from Copernicus and blended that into his pantheist mystical cosmology, so he tells us got the idea of multiple inhabited worlds from "the Divine Cusanus".

That was Nicholas of Cusa (1401-1454), who published his speculations about an infinite, unbounded universe with multiple worlds and possible alien inhabitants in them in his  De Docta Ignorantia (Of Learned Ignorance) in 1440.  Like Bruno, Cusanus' cosmology was speculative and intuitive rather than scientific and even the Catholic Encyclopaedia doesn't bother to try to claim otherwise, noting it was "based on symbolism of numbers, on combinations of letters, and on abstract speculations rather than observation".  But Cusanus' writings had a clear and acknowledged impact on Bruno.  Here is Cusanus on extraterrestrial life:
"Life, as it exists on Earth in the form of men, animals and plants, is to be found, let us suppose in a high form in the solar and stellar regions. Rather than think that so many stars and parts of the heavens are uninhabited and that this earth of ours alone is peopled   – and that with beings perhaps of an inferior type – we will suppose that in every region there are inhabitants, differing in nature by rank and all owing their origin to God, who is the centre and circumference of all stellar regions."

So was Cusanus burned at the stake for this heresy?  No, he wasn't.  As Michael J. Crowe comments wryly:
"A superficial knowledge of the plurality of worlds debate .... might lead one to suspect that these claims of Cusanus reveal a person with little sense of the politically acceptable, if not a man destined for imprisonment or burning at the stake .... (yet) eight years after his Of Learned Ignorance he was made a cardinal of the Catholic church." (p. 8)

Cusanus was not simply a cardinal, but also a Papal Legate, second only in authority to the Pope himself.  He was also a respected and renowned scholar and theologian and considered one of the great intellects of his day.  

And he was far from the only medieval thinker to ponder at least the possibility of "other worlds".  While the scientist and philosopher Nicole Oresme (c. 1320-1382) was of the view that there is only one "corporeal world", he insisted that God's omnipotence meant that the possibility of other worlds could not be ruled out, noting "God can and could in his omnipotence make another world besides this one or several like or unlike it" (Orseme, Livre du ciel, I.24).  Another medieval philosopher, John Major (1467-1550), a Scot working at the University of Paris, went much further, citing Democritus and declaring "naturally speaking there are infinite worlds [and] no argument can convince one of the opposite" (See Edward Grant, Planets, Stars, and Orbs: The Medieval Cosmos, 1200-1687, Cambridge University Press, 1994, p. 166-7 and notes).  Finally, around the same time as Cusanus, the French theologian William of Vorilong was pondering the implications of multiple inhabited worlds:
"If it be inquired whether men exist on that [other] world, and whether they have sinned as Adam sinned I would answer no, for they would not exist in sin and did not spring from Adam. .... As to the question whether Christ, by dying on this earth could redeem the inhabitants of another world, I would answer that he is able to do this even if the worlds were infinite, but it would not be fitting for him to go into another world that he must die again." (quoted in Grant, p.158)

So given all this medieval speculation about possible multiple worlds, possible extraterrestrial inhabitants and even pondering on the soteriology of aliens, it is reasonable to conclude that ideas that Bruno tells us he got from an esteemed cardinal of the Catholic Church would be low on the list of things that would bother the Inquisition.

This was certainly my personal view until last year, when Alberto A. Martinez of the University of Texas published a paper arguing that the "multiple worlds" issue was not only part of the problem, but was the central accusation made against Bruno.  In "Giordano Bruno and the heresy of many worlds" (Annals of Science, Volume 73, 2016, Issue 4, pp. 345-374) Martinez details the strong tradition of theological opposition to the idea of a multiplicity of worlds and then presents detailed evidence, including the account of the condemnation of Bruno by Gaspar Schoppe, that Bruno's claim "that worlds are innumerable" was the central accusation against Bruno.  While Martinez makes a strong case for the latter point, he fails to take account of the other tradition that was in favour of possible or actual multiple worlds, characterised by Oresme, Major, Vorilong and Cusanus.  But perhaps a case could be made that these speculations could be tolerable in the comparatively free-wheeling theological atmosphere of the fourteenth and fifteenth centuries in a way they could not be in the far more paranoid and censorious context of the Counter Reformation.  Especially if they are being espoused by a Pantheistic contrarian who also seems to have believed a whole grab-bag of other heretical theological ideas.




Bruno, Science and "Woo"

Martinez is less convincing in his arguments that the multiplicity of worlds issue was the central charge against Bruno, but his argument makes it fairly clear that it was one of the charges that led to his execution and that it was most likely one of the lost "eight propositions" put to Bruno by Bellarmine.  The key point to remember here, however, is that Bruno's multiple worlds ideas was, like the rest of his cosmology, wholly mystical and totally non-scientific.

It was part of a whole world view that depended on ideas that the defenders of the "martyr for science" myth would regard as ridiculous "woo": planets and stars inhabited by souls and moved by spirits, the transmigration of souls and reincarnation and a Pantheism that would be not out of place in the rambling lectures of the aforementioned Deepak Chopra.  As with heliocentrism, Bruno did not originate the idea of multiple worlds.  And as with heliocentrism, he adopted it for mystical reasons while rejecting and even scorning any attempt at proving it empirically.  The fact that, purely by chance, he stumbled into accepting two ideas that, much later, proved to be scientifically correct, while promulgating a crackpot mystical, Hermetic and magical universe that was a philosophical dead-end does not make him a martyr for science.

At best, Bruno could be considered a martyr for untrammelled free speech and ideas - two concepts that were essentially unknown in the sixteenth century.  We can look at the way sixteenth century people thought, their subservience to hierarchy and traditions of authority and their acceptance of social structures that we would consider oppressive and find all this alien and unpleasant.  But to judge the past by the values of the present is a basic historiographical fallacy.  At best, anti-theists can use the Bruno case as a stick with which to beat churches which make claims to universal authority and transcendent wisdom, but since those same churches also plead human fallibility, it's unlikely to be a beating that has much effect.  Such a tactic usually has no purpose other than making the beater feel smug.

However you look at it, a detailed examination of Bruno's life and work makes it quite clear that he was no martyr to science.  The idea that his execution somehow set back science or even that it demonstrates some antipathy toward science by the Church is patent nonsense.