Segulos, Magnets, and the Supernatural

The post about the strangest segulah ever led to much discussion about the history of Judaism's approaches to segulos. I thought it would be worthwhile to re-post a discussion on this from a few years ago, regarding the view of Rashba (a.k.a. Rabbi Shlomo Ibn Aderes, 1235–1310). Rashba discussed this matter in the context of his disagreeing strongly with Rambam's across-the-board dismissal of all magic (and similar phenomena for which there is no rational explanation) as being nonsense and thus prohibited. Rashba points out that the Gemara is full of such things, which (unlike Rambam) he takes authoritatively, and he stresses that these practices are endorsed even though there is no rational explanation for them. Rashba later delivers what he believes to be the coup de grâce:
עוד יש לי מקום עיון בדברי הרב ז"ל שכתב אמרו בפי' כל שיש בו משום רפואה אין בו משום דרכי האמורי. רוצה בזה כל מה שיגזרהו העיון הטבעי הוא מותר וזולתו אסור. ע"כ. ואני שואל כמסתפק בדברי הרב ז"ל מהו הדבר שיקראוהו הרב ז"ל שיגזרהו העיון הטבעי. אם מה שיגזרהו עיון חכמי' שחברו ספרים בטבע כאריסטו וגאלינוס וחבריהם שחברו ספרים בטבע הסמים והמסעדים המועילים לפי עיונם וכל מה שלא השיג עיונם הוא בכלל איסור דרכי האמורי. לפי שעיון חכמים אלו שהשתדלו בחכמת הטבע כולל כל מה שאפשר להיות פעל כל בעל טבע בטבעו. ואצל עיון חכמים אלו יפסק מאפשרות העיון הטבעי. זה באמת מה שלא יקבלוהו השכל כי באמת הדברים הפועלים בסגלה אין פעולתם בפלא מהם אלא בטבע מסגל, רצוני לומר בטבע לא ישיגנו עיון החכמים ואפילו החכם שבחכמים לרוב העלם הטבע ההוא מכלל המין האנושי מצד שהוא אדם, כסגלת אבן השואבת שהברזל קופץ עליה ויותר מזה מורגל בירדי הים באניות תוחבין מחט בחתיכת עץ צף על פני המים ומראין לו אבן וישוט על פני המים עד שיפנה אל פני הסדן ושם ינוח - ולא ישיג עיון טבע זה כל חכם שבחכמים אלו של חכמת הטבע. (שו"ת הרשב"א חלק א סימן תיג)
Here, Rashba argues that it is impossible to claim that only phenomena for there is a rational explanation are real and permitted. His reason is that there are phenomena that undeniably exist, and yet for which there can be no scientific explanation. The example that he brings is the magnet, and its use in a compass. These things operate neither in the realm of the miraculous, nor in the realm of the natural; instead, they operate in the realm of segulah. Rashba notes that "the wisest of scholars in the sciences can never grasp the nature" of such things.
Now, I myself, in my monograph on demons, argued that one cannot simply assert that those who believed in demons and suchlike were not rationalists. Things looked different in the medieval period, and some people believed in such things for rational reasons. Nevertheless, there is still an enormous gulf separating the rationalist Rishonim of Spain from the mystical Rishonim and from the non-rationalist Rishonim in Ashkenaz.
Superficially, Rashba's discussion appears not too far removed from that of Ralbag. Ralbag was an extreme rationalist, yet he likewise asserts that magnets can only be explained in terms of being a segulah. However, the term segulah as used by Ralbag (and Rashba) has been borrowed from pharmacology, where it refers to peculiar properties which cannot be explained in terms of its constituent elements (see Y. Tzvi Langermann, "Gersonides on the Magnet and the Heat of the Sun"). In applying it to magnets, Ralbag is claiming that the nature of the magnet cannot be grasped by the science of his day; but he is not explaining it to be a supernatural phenomenon, and he did not see it as reason to accept the validity of magic.
For Rashba, on the other hand, there is no distinction between that which science cannot currently explain, and that which it will never explain. Rashba's point is not that there are "empirically tested phenomena work through the principles of science despite the fact that we do not understand these principles." On the contrary; his view is that there are principles other than laws of science and nature that operate. Unlike Rambam, who realized that magnets are a solely naturalistic phenomenon, Rashba believed that magnets operate in a different realm - that of segulah. According to Rashba, the framework within which segulos work is precisely not the framework of science and nature. He therefore sees magnets as reason to accept belief in magic and all such phenomena. The lack of any conceivable scientific explanation for a phenomenon is no reason whatsoever to doubt its existence.
Now, it is true that even today, we don't really understand what magnetism, or gravity for that matter, actually is. We can measure and describe how it works, but we still don't know what it fundamentally is. Nevertheless, we are fully confident that it is a natural, rather than supernatural, phenomenon. Rambam and even Ralbag felt the same way, which is why their inability to comprehend magnetism or other phenomena did not prevent them from dismissing other phenomena as clearly false. The line between science and pseudo-science is not always clear, but there are nevertheless many things that we confidently dismiss as non-existent. Rashba, on the other hand, did not believe that we can ever dismiss phenomena as scientifically impossible and false - and saw magnets as evidence for this.
It's nice, and very tempting, to think that whatever we believe to be the correct approach to Judaism has always been the approach of great Torah scholars. However, that is often not the case.