Juan Gomez writes…
As readers of this blog know, I have been exploring the application of the ESD framework for interpreting the history of philosophy and science in early modern Spain. Throughout the past 18 months or so I have been sharing my research and thought on the experimental/speculative divide in Spain, the application of the experimental method in medicine and natural philosophy by the Novatores, and the attacks on the “new philosophy” by Spanish scholastic thinkers. It is time to take stock on the ESD in early modern Spain, and I want to begin by focusing on one particular issue in this post.
One of the purported advantages of applying the ESD framework is that, unlike the terms “rationalist” and “empiricist,” the terms “experimental” and “speculative” were in fact the terms used by early modern philosophers. However, as is evident in a number of my posts, it seems that in early modern Spain the rationalist/empiricist distinction is used by the players in the debate. Could this perhaps mean that the ESD framework is not that appropriate for the Spanish context? I don’t believe this is the case. Let’s start by examining the use of the empiric/rationalist distinction I have referred to in previous posts.
Almost all of the figures involved in the intellectual debates in early modern Spain were either within or had some connection to the medical context. It is in this context where we see the terms “empirico” (empiric) and “racional” (rational) in use. The terms appear opposed to each other, where the empiric doctors are those that focus on experience and observation and the rational doctors those who follow the teachings of Galen and Aristotle. This being the case, we could perhaps claim that the ESD has no clear advantage over the RED framework. In fact, we could even think that the RED is better, since the figures involved in the debate were using “empirico” and “racional.”
It is important here to remember that the frameworks have two dimensions: a historical and a historiographic one. In the Spanish case, the presumed advantage of the RED would hold at the historical level, but it is yet to be seen if this carries over to the historiographical level.
However, even at the historical level the RED framework’s advantage is doubtful. As we have explained, there is a very important difference between the two frameworks: while the ESD highlights a methodological distinction, the RED highlights an epistemic one. As we examined in my last post, while Boix uses “empirico” and “racional”, he uses those terms to refer to a methodological distinction, not an epistemic one. So the use of the terms by Boix does not line up with the way they appear within the RED framework.
In fact, the fact that the way Boix uses the terms differs from the RED way actually points to the advantages of the ESD at the historiographical level. Even if the figures within the debate were not using “experimental” and “speculative”, the fact that the ESD focuses on a methodological distinction makes it a more appropriate framework for our interpretation of the period.
There is another consideration that can shed light on our present discussion. As I mentioned earlier, the empiric/rational distinction is rooted in the medical context. In other contexts, as in astrology and natural philosophy, the debate is not phrased in those terms. The Novatores, guided by the work of Benito Feijoo, phrase the methodological distinction in terms of the systemic/experimental divide, where “the former explain nature according to some system; the latter discover it through the way of experience.”
So it seems that, in spite of the empiric/rationalist distinction that appears within the medical context in early modern Spain, the ESD is still a more appropriate framework for our interpretation of the intellectual development in the Iberian Peninsula. This being said, there is still a lot of work to do in order to give a fuller account of the use of “empiric” and “rational” by early modern Spanish figures and their relation to the experimental/speculative divide.
Juan Gomez writes…
I have been discussing the reception and development of experimental philosophy in early modern Spain in a number of posts in our blog. In my previous entry, I introduced a 1711 text by Marcelino Boix which presents an interesting sketch of the relationship between natural philosophy and medicine. In particular, we saw that Boix sets out to defend empiric doctors from the attacks of rational dogmatists. However, I did not examine in detail Boix’s conception of empiric doctors. It is to Boix’s description of the empiric sect that I want to turn to now.
Boix establishes his definition of the empiric sect by placing it in relation to what he calls “the three main sects of natural philosophy”: sceptics, academics, and rational dogmatists. While all three sects are driven by the search for truth, they differ in the accounts of their results:
Rational dogmatists brag that they have found the truth, in contrast to the Sceptics, which have not been able to find it, in spite of the fact that they have never lost hope of finding it…The Academics have completely despaired in finding it. While Rational dogmatists insist on giving an answer to every question in nature, Academics and Sceptics suspend their judgment.
Boix wants the reader to think that out of the three sects, the Academic one is the best. This is made evident in his description of the way the three sects have made an impact on the history of medicine. Boix comments that medicine up to the eighteenth century was founded on the rational dogmatist philosophy, which has Aristotle and Chrysippus as its leading figures, since “they were the first who taught Dogmatists and Scholastics to talk loud when it comes to the search for truth.”
The academics are discarded quickly, since they have given up in the search for the truth. The sceptics are considered in a more favorable light, since they are the foundation for the empiric doctors, who Boix sides with. He mentions that the Sceptics had Pyrrho for their guide, who “acquired the knowledge, solely through the light of nature, that Philosophy and Medicine were not learnt through disputes and useless questions.” Boix starts his defense of the empiric sect and finds support in the work of Robert Boyle. He quotes a passage from Boyle’s Certain Physiological Essays in order to show that the way rational dogmatists conduct their research does not yield results:
If a physician be asked, why rhubarb does commonly cure looseness, he will probably tell you as a reason, that rhubarb is available in such diseases, because it hath both a laxative virtue, whereby it evacuates choler, and such other bad humours as are wont, in such cases, to be the peccant matter; and an astringent quality, whereby it afterwards arrests the flux. But if you further ask him the reason, why rhubarb purges, and why it purges choler more than any other humour; it is ten to one he will not be able to give you a satisfactory answer.
Boix uses the quote to prove a point: that the rational dogmatists (focusing their accounts on occult and secondary qualities) cannot explain why rhubarb purges choler more than any other humour. He comments that not even Robert Boyle, “the Prince of philosophy in our time”, can explain why rhubarb purges choler more than any other humour. The point is that those partial to the empiric sect know when to abstain from giving an answer, unlike the rational dogmatists who make up their explanations.
This brings Boix to ask an interesting question to his sketch: If none of the sects can give us answers, what is the difference between them? Boix reiterates his suggestion that while rational dogmatists claim to know certain truths, without proof, sceptics focus on the plausibility of their explanations based on experience:
If, like Valles says, a doctrine is more probable than another, because it has better foundations both ab extrinseco and ab intrinseco, then in Philosophy the Sceptics will make it more probable than the Rational dogmatists, the latter make doctrines plausible based on the authority of many, which is ab extrinseco, and on reason, which is ab intrinseco. But the Sceptics laugh at all this, since with experience they prove both reason and authority wrong. The same can be said of the Empiric doctors, given that, despising useless questions they search for experience, because they know that it will bring them closer to the truth (even though they lose hope in ascertaining it), and in this way Sceptics and Empirics make their doctrine more plausible than the Rational dogmatists do: since opposed to experience there can be no disputes, especially when it is accompanied by reason.
Boix’s description of the distinction between rational dogmatists and sceptics/empiric doctors closely resembles the speculative-experimental divide: rational dogmatists, just like speculative philosophers, turn to authority, syllogisms, and occult qualities to ground their doctrines; sceptics/empiric doctors rely solely on experience in their search for truth, just like experimental philosophers. Boix’s references to Boyle and Sydenham also suggest that his empiric doctors are committed to the same methodology the experimental physicians promoted. In this sense, Boix’s work can help us decipher the way in which Spanish philosophers received and interpreted experimental philosophy, giving way to the philosophy of the Novatores, a group that would shape the development of early modern Spanish philosophy.
A couple of months ago Peter Anstey directed me to a book by Miguel Marcelino Boix, a Spanish doctor and professor of surgery at the Universidad de Alcalá. The book, a defense and commentary on the first aphorism of Hippocrates, was published in 1711 and it contains some references to the experimental philosophy of the time. But what really caught my eye was the use Boix makes of the terms rationalism (racionalismo) and empiricism in medicine, and the connection of the latter term to experimental philosophy. In this and a couple of future posts I want to present Boix’s text and hopefully shed some light on the connection between experimental philosophy and empiricism (and the ESD) in early modern Spain.
Vita brevis, ars longa, occasio praeceps, experimentum periculosum, iudicium difficile.
This is Hippocrates’ first aphorism, the focus of Boix’s text. The Spanish doctor gives his analysis of the five phrases of the aphorism while criticizing various other interpretations of them. It is during his account of the fourth phrase, experimentum periculosum, that Boix contrasts the two sects, rational dogmatists (dogmáticos racionales) and empirics (empíricos), and begins to connect the latter with experimental philosophy.
Boix begins by offering his interpretation of the phrase, explaining that it says that doctors “never apply any medicine to the human body with absolute certainty that the desired effect will result.” In this sense, the phrase serves as warning to doctors, both rational and empiric, to be mindful of the limits of our knowledge and experience regarding medicine. However, Boix comments, some rational dogmatists have taken the phrase to mean that “experience is dangerous and false if it is not accompanied by reason.” This interpretation is used by rational dogmatists to attack the empirics, given that they follow experience blindly without any reference to reason. But Boix believes that this description of the empiric doctors, which is popular among people, is flawed. It is this mistaken account of the empirics that leads him to explain the differences between the two sects.
Given that the rational dogmatists attack the empirics for detaching reason from experience, Boix begins by examining the reasons the former give in their accounts.
They (rational dogmatists) say that their Medicine and Philosophy is founded on the four Elements, and the four humours; look at these four columns, these four strong pillars. And so they say, that knowing that there is heat, cold, wet and dry; blood, yellow bile, phlegm and black bile, they know all the effects they want, and that solely with the knowledge of these two quartets they have enough to defeat even the toughest questions contained in Natural philosophy and all of medicine. To this they add, that they are extremely happy, that Galen and Aristotle,their Princes, one in Medicine, the other in Philosophy, knew all they could, because neither to them or their disciples, has a problem been put forward, whether Physical or Medical, that they have not been able to solve solely by knowing that there are four qualities, and four humours.
By contrast, the popular opinion of the empirics is that they focus solely on experience and never give reasons for it; they “are those tricksters or scoundrels that come from Foreign Nations with half a dozen remedies, wanting to cure all kinds of diseases with them.” But this is a false depiction of the empiric sect. In order to explain what the empiric doctors are really about, Boix refers to the main sects in natural philosophy: sceptics, academics, and rational dogmatists. But we will get into that in my next post. I want to stop here to talk about the popular concept of the empiric doctors and the connection with experimental philosophy.
As Alberto Vanzo pointed out in a previous post, “experimental physicians” saw themselves as opponents of “empirical physicians.” But the text by Boix brings in a new scenario for our consideration. It seems that in Spain, rather than seeing themselves as opponents of the empirical physicians, experimental physicians felt that were indeed part of the empiric sect and opposed the rational dogmatists. However, the position of the Spanish doctors is not different from that of the physicians described by Alberto in his post. When doctors like John Gregory and Friederich Hoffman described themselves as opponents of the empirical physicians, they had in mind the popular concept of empiric that Boix points out in his text. The Spanish doctors, just like their Scottish and German counterparts, saw themselves as opponents of that specific kind of physician. The difference lies in the fact that Spanish physicians believed that the true empirical physicians were far from the popular depiction of empirics. In fact, the way they described the true empirical doctors is very similar to that of Gregory and Hoffman regarding experimental physicians. It is this description of the empiric sect that we will turn to in my next post.
Juan Gomez writes…
This is the final post on my first series on the debate between scholastics and novatores in early modern Spain. In the first post of the series I introduced two figures who had a heated debate concerning the status of astrology: Martin Martinez representing the novatores, and Diego de Torres Villaroel defending the scholastics. We saw that Martinez calls for a ban on astrology on methodological grounds. He criticizes those scholastics (specifically Villaroel) who rely on astrology for writing only from their imagination with no regard for observation and experiment.
In the second post of the series we looked at Martinez’s arguments in more detail. We focused on his rejection of the application of astrology in natural philosophy. His attack revolves around the claim that the astrologers explain natural phenomena by referring to obscure causes where the phenomena in question are clearly accounted for by referring to evident causes. He shows that in medicine and natural philosophy there is no need to consult the stars. Villaroel was offended by this attack on astrology and promptly published his reply, Entierro del Juicio Final, y vivificacion de la astrologia (Burial of the Final Judgment, and revitalization of astrology). Juicio Final was the title of Martinez’s attack, and in today’s post we will examine Villaroel’s attempt to bury it.
Villaroel sets out to respond to Martinez’s criticisms and show that astrology in fact is useful for our natural, moral, and political inquiries. We saw Martinez complain about the practice of placing celestial bodies as the causes of natural effects, in particular when it comes to explaining the ailments of the human body. Surprisingly, Villaroel responds to this criticism by saying that these are not mere conjectures, but are actually founded on observation and experience:
That Astrologers assign to each body part its Planet, or its star Sign, is not as dissonant as the Doctor [Martinez] judges; since in fact the analogy and conformity between the temper of the planets, and the cold, dry, wet, and warm parts of the wind, are such qualities not by the devotion of Astrologers, nor by their words, but because God made them that way, giving each its temper and quality: observation and experience, the mother of knowledge (which Martin lacks), has taught us so, as it taught our Masters; if not, let’s ask the Doctor: why is chicory cold? I believe he will answer, because God made it so, and gave it such quality. And I would ask further: has God told you which quality it has? No sir, he will answer (he is not so holy as to have revelations), experience has taught it to me and so have all Medical Authors. Well we astrologers say the same about the qualities of the Planets and Stars.
Despite Villaroel’s insistence that it is through experience and observation that astrologers know the qualities of the planets and their effect on the human body, there is no reference at all to an observation account to support the claim. Instead, Villaroel blames Martinez for not properly studying the work of the authors cited by astrologers (traditional scholastic figures, such as Aquinas and Galen), and so his ignorance leads him to his unfounded criticism.
In fact, it is this ignorance, Villaroel claims, that leads Martinez to think that astrologers refer to occult causes to explain natural phenomena:
I encountered then a Cartesian rascal, who told me with a hollow cough while stroking his beard: those influences you confer to the Stars are either occult qualities, which means you do not know if they exist, or they are evident qualities, and if so you are mistaken in not pointing them out. I replied to the Cartesian, identifying that his argument was as much of a cheat as him, and said: they are occult qualities to you, to Martin, and to all others who, not having studied them, ignore them completely, and because they appear occult to the ignorant, it does not follow that they do not exist, and they are evident qualities to those of us who have studied them, and we are not in error, since we point them out in our almanacs.
Villaroel insists on replying to the criticisms by pointing out Martinez’s supposed ignorance, and instead of supporting his argument with data, he focuses on quoting authors that recommend the study of astrology to insist that Martinez is not only ignorant, but also a terrible physician. Villaroel refers to passages from the work of Galen, Avicenna, and Hippocrates, where they all comment on the necessity of the study of astrology for the proper exercise of medicine. But other than the quotes, Villaroel’s claims are not backed up by observation and experience, despite his claims that such is the source of the astrologer’s knowledge.
This debate between Villaroel and Martinez has an interesting feature: it shows that there was more to the experimental/speculative divide than mere rhetoric. Both our authors use the rhetoric of the new philosophy, placing experience and observation as the only true source of knowledge; but while Martinez does refer to observational data to back up his explanations, Villaroel does not go beyond the authority of scholastic figures and their texts. What we have here is a clear case of the two sides in the ESD, where the experimental methodology supported by Martinez is contrasted with the speculative ways of Villaroel. Stay tuned for further posts on the ESD in early modern Spain!!
Juan Gomez writes…
In one of my previous posts regarding early modern Spain I referred to Martin Martinez, a physician who was an avid promoter of the experimental method. Today I want to examine a debate he had regarding the rejection of astrology. In this blog we have provided many illustrations of the methodological statements typical of those who promoted and adopted experimental philosophy. We have shown the insistence in rejecting the work of those that rely solely on speculation, but we have not yet seen any examples of the work of speculative philosophers. The case of astrology in 1720s Spain can shed some light on the kind of speculative science rejected by experimental philosophers like Feijoo and Martinez.
Besides the comments he added supporting Feijoo’s work, Martinez wrote a whole essay (Juicio final de la astrologia (The final judgment of astrology)) rejecting astrology in 1727. He distinguished between astronomy and astrology: while in the former “the regular movement of the stars is observed…times are computed, lunar cycles determined, and eclipses are predicted”, in the latter astrologists “feign a volume (only intelligible to them) in the heavens where they find written mundane events, wars, famine, pests, shipwrecks, harvests, diseases, and all other fortunes of human life.”
In the comments he makes defending Feijoo’s work, Martinez clarifies that the problem with astrology is that it is not founded in observation and experience:
“Upon reflection, according to what reasoning, or experience, do the astrologists found their imagined influxes of the stars and planets? On what grounds do they know that Mars burns, and Saturn cools? They probably say, because Mars is red and Saturn grey: though according to this they should also say that carnations burn and quicklime cools; and if they say they experience heat coming from Mars, I do not understand how they know it comes from it, and not from another cause.”
Martinez goes on listing a number of claims astrologists make, in particular related to the effects the movement of the planets and stars, eclipses, and comets have on the health of individuals. But Martinez is directing his claims to one individual in particular, Diego de Torres Villaroel, a mathematician and astrologist who published yearly almanacs with predictions under the pseudonym “el gran Piscator de Salamanca”. Leaving the calendars aside, Torres also published an essay containing his ideas on the nature of the earth and the heavens. The text was first published in 1724 under the title Viaje fantastico del gran Piscator de Salamanca (The fantastic journey of the great Piscator of Salamanca), and then again in 1739 as Anatomia de todo lo visible e invisible (Anatomy of all that is visible and invisible). It is this book that Martinez targets, and will serve as our illustration of the kind of speculative philosophy the novatores rejected.
Torres’ essay gives an account of the structure and composition of the earth and the heavens, all this prompted by an eclipse which occurred on May 22, 1724. The explanation of the constitution of both spheres of the universe (heaven and earth) is given through a story where the great Piscator travels to the depths of the earth and then upwards to the heavens, illustrating to his fellow travellers all the details of both spheres. As is clear from various passages, Torres’ claims are never supported by observations, but only by the musings of his mind and astrological calculations. The opening lines of the dedicatory epistle highlight the speculative nature of the work:
“Hand over hand the soul, without resorting to the use of the external senses, and reason, in arms of a jobless idleness, let fantasy to its word, and running through the spaces of imagination it recited in their theatre the following story.”
Torres acknowledges that he writes from his imagination, but asserts that he reaches the same conclusions others (like Kepler, who studies “the cosmic machine”) have:
“With no other guide but my imagination, and sleeping like a log, I have completed the same journeys [as Kepler and Kircher].”
Although lines like the ones just quoted give the impression that Torres must be speaking metaphorically, it seems that his ‘discoveries’ had no other foundation that the inspiration he got from studying astrology. In the opening lines of the story, a character contrasts the method of astrologists like Torres to those who studied the eclipse by means of observation:
“How is it that you, Mr. Astrologist, in an eclipse whose nature and effects have excited the North and their less lazy Observers have been writing about, you do nothing other than note down in your Prediction the simple calculation of the time and the day?”
Torres defends himself, and convinces his companions to go on a journey through the earth and the heavens in order to understand the nature of eclipses and their effects on human events. In their journey through the earth the astrologist points out where hell and purgatory reside deep down where there is no influence of the heavenly bodies. Then they travel upwards to the heavens, where the astrologist explains the different levels, how all is made of ether, and its effects on the earth. He explains how when a comet is “of the nature of Saturn”, it “causes colds, leprosy, haemorrhoids, paralyses, and chronic diseases”; if it is dominated by Mars on the other hand, it causes “cruel dysentery, rotten fevers, delirium, haemorrhages…”
I could go on drawing on passages from Torres’ book, but the ones quoted above are enough to illustrate the opposition to astrology that the Spanish novatores insisted on. It is important to remember that figures like Feijoo and Martinez had a genuine worry regarding the influence of astrology. Unlike our present time, in the early decades of the eighteenth century astrology was still considered by many as a genuine science, and it was this (more than the almanacs) that motivated the novatores to call for a ban on astrology.
Juan Gomez writes…
One of the most exciting tasks of my research has been to track the introduction and reception of the ESD in early modern Spain. I have illustrated the adoption and praise of the spirit of experimental philosophy in various texts by the Spanish Novatores, and I looked in a bit more detail at the work of Benito Feijoo (posts 1, 2, and 3). In spite of the insistence to abandon scholastic and Aristotelian methods and science, the progress of natural philosophy in early modern Spain lagged in comparison to the rest of Europe. In fact, the Novatores themselves recognized this lack of progress, as is clear from a letter by Feijoo which I will be sharing with you today.
In 1745 Feijoo published a collection of letters, most of them responding to a range of criticisms directed against his Teatro Critico Universal. Letter 16 in the second volume of that collection is Causas del atraso que se padece en España en orden a las Ciencias Naturales (Causes for the backwardness of Spain regarding the Natural Sciences). Feijoo gives six reasons (causes) for this backwardness, in all of them placing the blame on the scholastic philosophers and their way of thinking.
The first cause is the narrowness of most of the teachers, whom Feijoo describes as “Everlasting ignorants, set on knowing only a few things, for no other reason that they think that there is nothing else to know, aside from those few things they know.” Feijoo goes on to describe this kind of teacher, who only knows scholastic logic and metaphysics, and laughs when hearing words like ‘new philosophy’ or ‘Descartes.’ However, when asked to explain the claims of the new philosophy or those held by Descartes, they stay silent because they have no knowledge of them. (Note: experimental philosophy and new philosophy are not identical, even though the former was sometimes referred to by the latter name. For example, Descartes was commonly regarded as a new philosopher, but not so much as an experimental philosopher.)
People like the teachers described above have spread throughout Spain a disdain for ‘the new’, the second cause identified by Feijoo. They think that, since every sacred doctrine labelled ‘new’ is rejected immediately for being suspicious, the same rule applies for theories about the natural world. So they must reject the teachings of Galileo, Huygens, and Harvey, as well as all the new instruments and machines developed in the seventeenth century, holding on to their scholastic and Aristotelian science as the one true system. Feijoo comments that this attitude backfires, since rejecting anything because it has been labelled ‘new’ entails that there could never have been any progress in natural science (the Aristotelian system was also ‘new’ at some point).
But aside from rejecting the new philosophy because it is ‘suspicious’, the Spanish scholastics also reject it because all it presents is “a few useless curiosities.” (This is the third cause given by Feijoo.) What the scholastics do not realize, Feijoo tells us, is that under this criterion their theories lose against those of the modern: “Which would be more useful: to explore in the physical world the works of the Author of Nature, or to investigate through large treatises derived from the Entity of Reason, and logical and metaphysical abstractions, the fictions of human understanding?” Feijoo also contrasts between the method of learning in the confines of the classroom of the scholastic, and that of the modern, based on experiments and observations.
The fourth cause rests on the mistaken notion held by the scholastics that the new philosophy is identical to Cartesian philosophy. Feijoo comments that although Cartesian philosophy might be new philosophy, new philosophy is not Cartesian philosophy, the same way men are animals but animals are not men. Highlighting the ESD, Feijoo goes on to divide philosophy into two kinds:
“Philosophy, taken in all its extension, can be divided into Systematic and Experimental. The Systematic has many different members, e.g. Pythagoric, Platonic, Peripatetic, Parascelsistic, or Chemical, that of Campanella, that of Descartes, that of Gassendi, etc.”
Feijoo clarifies that he advocates not that the Spaniards embrace one of the former systems, but rather that they do not close their eyes to “Experimental Physics”, which:
“without regard for any system, investigates the causes through the sensible effects; and where it cannot investigate the causes, it settles for the experimental knowledge of the effects… This is the physics that reigns in Nations: the one cultivated by many distinguished Academies as soon as it emerged in France, England, Holland, Etc.”
The achievements of this experimental physics are illustrated by the discoveries regarding our knowledge of the properties of air, of fluids and mechanics, all of them unattainable by relying on the physics of the schools.
Feijoo identifies as the last two causes the mistaken idea that the new philosophy clashes with religion, and the jealousy and pride of the scholastics in Spain that prevented them from accepting the triumphs of other men of science from different European nations. I will not examine them here. Instead I want to conclude the post by pointing out that, not only there is enough evidence to confirm the presence of the ESD (at least in some form) in early modern Spain, but also that it can provide us with an interesting framework to interpret the development of natural philosophy and science in early modern Spain.
Juan Gomez writes…
In my last two posts I commented on an essay by Benito Feijoo. First we examined how he pictures the history of philosophy as the contest between two ladies —Solidína (experience) and Idearia (imagination) — to conquer the world. He sides with experience, and we also examined some of the arguments he gives to support the adoption of the experimental method and the rejection of mere speculation. In today’s post I want to follow Feijoo further, examining in particular his thought that just as we must abandon speculation when it is unaided by experience, we must also be cautious and keep in mind that experience without reasoning can also lead us astray in our quest for knowledge.
After spending most of his essay showing (through examples) that the proper path to knowledge is to follow the experimental method, Feijoo concludes with 3 capital errors that frequently take place in our experimental observations:
- We shall conclude this discourse, by pointing out three capital errors, which stem from lack of reflection in experimental observations. The first is that of taking for the effect that which is cause, and for cause that which is effect. The second is to take for cause something that only happens accidentally and has no influence at all. The third is, between two effects of the same cause, to take one as the cause of the other. I shall show examples of these three errors in observations pertaining to Medicine.
Of the first type of mistake Feijoo gives us a case where someone drinks water excessively to quench an overwhelming thirst. A few hours later such person suffers a fever, and it is commonly thought that the cause of the fever is the excessive consumption of water. However this is a false conclusion due to the lack of reflection when observing. If we reason, we can see that the sickness is the cause of the thirst that leads to the excessive consumption of water.
Feijoo warns us that this kind of mistake is very dangerous in medicine, since the lack of reflection and reasoning leads the physician to err in his diagnosis and prevent him from curing the disease.
The second kind of mistake takes place when we assign as the cause something that only happens accidentally. Feijoo tells us that this mistake is committed frequently by ‘superstitious souls’ that constantly assign to their diseases causes that have nothing to do with it. The most common mistaken cause in these cases is the weather. Patients frequently blame their disease on the weather: If during summer the weather is hot, the disease is taken to be caused by the excessive heat, but if summer is not hot enough, then this is also taken to be the cause of the disease.
Finally, the third kind of mistake happens when between two effects of the same cause we take one to be the cause of the other. Feijoo’s example is that of a man that performs an intense physical exercise or activity, then drinks alcohol in excess, and later suffers a fever. While most men would take the excessive drinking to be the cause of the fever, the truth is that intense exercise is more likely to cause a fever than excessive drinking.
This account of capital errors in experimental observation concludes Feijoo’s essay. So what are we to make of his thoughts on the ‘Lessons of Experience’? Well I believe that in Feijoo we have a clear example of the dispersion of the experimental method across the Iberian Peninsula in the first half of the eighteenth century. Feijoo might be the most influential figure of this period in Spain, but he certainly was not alone in the adoption and promotion of the experimental method: Andres Piquer, Manuel Martinez, Juan de Cabriada, and the circles of doctors in Seville and Valencia all shared the beliefs Feijoo expresses in his text. As we have seen in Feijoo’s work, the novatores believed that the correct path towards knowledge was the one taken by Bacon, Boyle, and Newton.