בבא מציעא דף מ''ו ע''א וע''ב. המשנה אומרת, "כל מה שנעשה ערך כספי באחר, ברגע שאחד רוכש אותו, השני רוכש את החליפו. כיצד זה? אם אדם מחליף שור בפרה, ברגע שאחד רוכש אחד, השני רוכש את השני." הגמרא שואלת שנראה שהמשנה מתכוונת שמטבע יכול לגרום להחלפה, (ואנחנו יודעים שזה לא המצב). אז רב יהודה אומר שזה אומר שאם אדם מעריך חפץ ברגע שהוא רוכש את הראשון, השני רוכש את השני. [כלומר, החלפה זו צריכה הערכה.] הגמרא שואלת בנקודה זו שה"הייתי חושב" היה נכון לפחות לפי לוי שחליפת מטבע יכולה לגרום לקניין. אז איך הבינה הגמרא את המשנה בנקודה זו? אחרי הכל, לדוגמה שהיא נותנת אין לה שום רלוונטיות למטבעות. (הדוגמה היא פרה תמורת שור.) תשובה. המשנה פירושה שמטבעות יכולים לגרום להחלפה, וגם פירות. (הדוגמה של שור לפרה היא דוגמה לפרי.) אבל עבור רב נחמן שמחזיק פירות לא יכולים לגרום להחלפה, מה יכולה להיות הכוונה? כאן תוספות שואל על רבינו תם שאולי המשנה קידושין דף כ"ח מדברת על החלפה שווה תחת שווה, ובמקרה כזה פירות יכולים לגרום להחלפה לפי רבינו תם. הוא עונה שזה לא יכול להיות כך, מכיוון שסוף המשנה צריך להיות כמו ההתחלה, וההתחלה בבירור אינה שווה תחת שווה. אני לא מבין מדוע זה כך. לפי הייתי חושב (הוה אמינא) אנחנו מדברים על החוק שניתן להחליף מטבע. "כל מה שהופך לערך כסף עבור משהו אחר, ברגע שאחד רוכש את החפץ, השני רוכש את החפץ המוחלף." היכן אנו רואים כאן שלא מדובר על שווה תמורת שווה?תשובה אפשרית לשאלה זו של תוספות על רב נחמן היא שאולי רב יהודה אומר שהחליפין צריך להיות שווה עבור שווה, (שכן אחרת למה צריך להעריך את השווי הכספי של כל חפץ?) ולכן גישתו של רב נחמן שונה והוא חייב להחזיק "כל הנעשה דמים נאחר" פירושו כלים שאינם שווים עבור שווים. עם זאת, ברור שתוספות לא עונה כך. הוא גורס שאפילו דעתו של רב יהודה, שכאשר הוא אומר "כל הנישום דמים באחר", משתמע מכך שהם אינם שווים בערכם

Bava Mezia page 46 side a and b. The Mishna says, “All that is made monetary value in another, once one acquires it, the other acquires its exchange. How is this. if one exchanges an ox for a cow, once one acquires one, the other acquires the other.” The gemara asks that it seems the Mishna means that a coin can cause exchange, (and we know that is not the case). So Rav Juda says it means if one evaluates an object once one acquires the first the other acquires tthe second. [ie that exchange needs evaluation.] the gemara asks at this point that the hava amina (I would have thought) was at least true according to Levi or Rav that holds a coin can cause exchange. So how did the Gemara understand the Mishna at that point? After all, the example it gives has no relevance to coins. (The example is a cow and for an ox) Answer. The mishna means coins can cause exchange, and fruit also. (The example of a ox for a cow is an example of fruit.) But to Rav Nachman who holds fruit can not cause exchange, what could the Mishna mean? Here Tosphot asks on Rabainu Tam that perhaps the Mishna in Kidushin page 28 is talking about exchange equal for equal, and in that case fruit can cause exchange according to Rabbainu Tam. He answers that that can not be so, since the end of the mishna has to be like the beginning, and the beginning is clearly not equal for equal. I fail to see why this is so. according to the I would have thought (hava amina) we arre talking about the law that a coin can be exchanged. ''All that is made money value for something else, once one acquires the object, the other acquires the exchanged object. '' Where do we see here that it is not talking about equal for equal? A possible answer to this question of Tosphot on Rav Nachman is that perhaps Rav Judah means that the exchange has to be equal for equal, (since otherwise why would one have to evaluate the monetary worth of each object?) and therefore approach of Rav Nachman is different and he must hold “All that is made monetary value in other” means vessels that are not equal for equal. However, it is clear that Tosphot does not answer this. He holds that even the opinion of Rav Judah is that when he says one must evaluate the worth of each object, that implies they are not equal in value. -------------------------------------------------------------------------------------------------------------------------------------- ---- בבא מציעא page מ''ו ע''א וע''ב. The משנה says, “All that is made monetary value in another, once one acquires it, the other acquires its exchange. How is this. if one exchanges an ox for a cow, once one acquires one, the other acquires the other.” The גמרא asks that it seems the משנה means that a coin can cause exchange, (and we know that is not the case). So רב יהודה says it means if one evaluates an object once one acquires the first, the other acquires the second. [ie that exchange needs evaluation.] The גמרא asks at this point that the הווה אמינא (I would have thought) was at least true according to לוי (or Rav) that holds a coin can cause exchange. So how did the גמרא understand the משנה at that point? After all, the example it gives has no relevance to coins. (The example is a cow and for an ox) Answer. The משנה means coins can cause exchange, and fruit also. (The example of a ox for a cow is an example of fruit.) But to רב נחמןwho holds fruit can not cause exchange, what could the משנה mean? Here תוספות asks on רבינו תםthat perhaps the משנה in קידושין page כ''ח is talking about exchange equal for equal, and in that case fruit can cause exchange according to רבינו תם . He answers that that can not be so, since the end of the משנה has to be like the beginning, and the beginning is clearly not equal for equal. I fail to see why this is so. according to the I would have thought (הווה אמינא) we are talking about the law that a coin can be exchanged. ''All that is made money value for something else, once one acquires the object, the other acquires the exchanged object. '' Where do we see here that it is not talking about equal for equal? A possible answer to this question of תוספות on רב נחמן is that perhaps רב יהודה means that the exchange has to be equal for equal, (since otherwise why would one have to evaluate the monetary worth of each object?) and therefore approach of רב נחמןis different and he must hold “כל הנעשה דמים נאחר” means vessels that are not equal for equal. However, it is clear that תוספות does not answer this. He holds that even the opinion of רב יהודהis that when he says "כל הנישום דמים באחר", that implies they are not equal in value.

What's Wrong with Stereotypes? Michael Huemer Aug 3

MICHAEL HUEMER AUG 3 1. Opposition to Stereotyping I keep hearing that “stereotyping” is bad, and that it’s good to undermine stereotypes. For instance, if you have a TV show with a brilliant surgeon, you should make them a woman. Or black. Or, best of all, a black woman. Because that will defy stereotypes and thereby make the world a better place. If you make a picture of some business people in a meeting, you have to make sure that it does not reflect what most business meetings actually look like; rather, you should gender balance it and make sure to have three different races represented (see above photo). If someone tells a joke that relies on stereotypes about a group, that is “offensive” and hence evil. I guess because it reinforces the stereotypes? Or maybe it’s just evil to rely on a stereotype for anything. Back when James Damore was fired from Google, it was partly because he cited research to the effect that women tend to be higher than men in the traits of “agreeableness” and “neuroticism” from the 5-factor model of personality. In doing so, he was reinforcing stereotypes, which all decent people know to be evil. If a statement sounds like a stereotype, that alone is enough to categorically reject it. Most of the people who believe this have a predictable political orientation, and so you can usually count on a certain amount of hypocrisy. Thus, certain stereotypes are fine. You can stereotype white men as privileged oppressors, you can stereotype Republicans as uneducated, etc. It’s all a matter of stereotyping the right group in the right way. As long as your stereotype reinforces your political side, it’s cool. But I digress. My question: what exactly is supposed to be wrong with stereotypes? Why not use and reinforce them? 2. Problems with Stereotypes A. What are stereotypes? First, what is a stereotype? Usually, people are talking about stereotypes about groups of people (e.g., women, black people, doctors). (I guess you could also have “stereotypes” about any class of object, but we don’t care about non-human objects.) As far as I can tell, a “stereotype” is just a widely shared belief about what a certain class of people tend to be like. Aside: Maybe there are a few other conditions, such as: it can’t be something definitional, it has to differentiate the group from other groups, and it should be a statistical generalization. Thus, it isn’t a “stereotype” that bachelors are unmarried, or that black people tend to have two legs. But let’s not worry about all the details of the definition. What is wrong with using or reinforcing such beliefs? B. Are they false? Maybe the problem with stereotypes is that they tend to be false, or to lead people to make false judgments. On the face of it, this would be surprising. In general, people tend to form beliefs about observable reality based on observations, which generally tend to reflect that reality. If most people think that the winter is colder than the summer, that’s probably because the winter is colder than the summer. If people tend to think that humans generally have two arms, that’s probably because humans generally have two arms. Etc. Could it be that, when it comes to groups of people, we have a general tendency to go wrong about everything—that when we think a group has feature F, in general, the group usually doesn’t have F? This is possible, but it would be pretty surprising. Btw, notice that I’m talking about beliefs about observable (or otherwise easily accessible) properties of observable objects. It’s not so surprising that people get things wrong about unobservable things, like God or the origin of the universe. Or maybe it’s not quite that the group doesn’t have F at all; maybe it’s just that stereotypes tend to exaggerate real differences, so the group that is stereotyped as having F will have less F than people tend to think. These are common critiques of stereotypes among educated people. One might say there is a stereotype that stereotypes are inaccurate. These critiques, however, have the character of articles of faith—almost none of these educated people who are too smart to fall for crude stereotypes has ever actually checked on whether stereotypes tend to be accurate or not. It happens that we have evidence about this. Over 50 studies have been performed on the accuracy of demographic, national, political, and other stereotypes. The results are unequivocal: Stereotypes are not generally inaccurate, nor are they generally exaggerations. The truth is the exact opposite: stereotypes are generally accurate, except that they tend to understate real differences. There is basically no evidence that stereotypes tend to lead to inaccurate judgments. Psychologist Lee Jussim describes stereotype accuracy as “one of the largest and most replicable effects in all of social psychology”. See his paper for a general review of the evidence. (See also his blog post.) For example: A 2011 paper titled “Beliefs About Cognitive Gender Differences: Accurate for Direction, Underestimated for Size” reported results of a study in which they asked ordinary people to guess how men and women would perform on a series of cognitive tasks. The scientists then compared the ordinary people’s expectations to the reality. This is a straightforward test. It turned out that people’s guesses were correct about the direction of gender differences (which sex would perform better on which tasks) but that the actual gender differences were larger than people thought. Notice that this is the opposite of what educated, progressive, right-thinking people would presumably predict. But again, this really should not be at all surprising if you’re thinking non-ideologically. Human beings can observe each other. Most of us have had many interactions with men and women. It would be bizarre if, despite that, we kept having beliefs about gender differences that had no correlation with reality. C. Are they oppressive? Maybe the problem is that stereotypes—whether accurate or not—are oppressive. Maybe they stop individuals from attempting or succeeding in things that would defy the stereotypes, when they would otherwise have succeeded. This could be true, but it isn’t self-evident. One way this could work is that other people would judge you based on stereotypes and would refuse to take into account your own individual characteristics. This is another one of those things that educated, progressive people assume without checking the evidence. In fact, studies find individuating information (specific to individuals) has massively greater effects on people’s judgments of others than stereotypes do. Given a society of millions of people, I’m sure there are some people who are deterred from attempting something due to stereotypes, and who are thereby worse off. So that is a cost. On the other hand, there can also be costs to not having stereotypes—e.g., perhaps some people would be encouraged to do things that they would not be suited to, and they would thereby be made worse off. As a general rule, truth is good. Knowing the truth about things that are relevant to your interests can make you worse off sometimes, but in general, it makes you better off. So, given the accuracy of stereotypes, stereotypes are probably beneficial. But whether they are or not, trying to suppress them is a fool’s errand. Normal people won’t stop noticing group differences just because elites try to hide them; normal people will just conclude that the elites are dishonest propagandists. D. Stereotype threat Stereotype threat is a theory in psychology that says that the existence of stereotypes tends to cause people to act in ways conforming to those stereotypes. Particularly negative stereotypes. E.g., it is said that if you remind people of their race before giving them a scholastic aptitude test, then the black students will tend to perform worse, due to stereotypes about their race. If you remind people of their sex, then the women will supposedly perform worse on the math questions than they otherwise would. Some people claim that this effect actually explains the entire gap in test scores between blacks and whites. Of course that’s false (it derives from a simple misunderstanding of a graph in the original study—progressives then just kept passing on this misunderstanding to each other). The effect only (at most) slightly increases already-existing gaps. In Progressive Myths, I discuss several problems with the stereotype threat literature. Here is just one interesting point: There have been many studies of the stereotype threat effect. Most of them are done in the lab. Some of them use more realistic conditions than others, and four of them have been done using actual administrations of standardized tests. The more realistic the test is, the

I have been thinking about Kant and the later German idealists and I think the issues they deal with are important, and yet I do not think that any one of them alone can be taken as the right answer, Rather I think each of has some good points and yet can not be considered to have the whole picture. To take Kant himself as the right approach misses the obvious problems in his system that were noticed right away almost before the ink was dry on the first edition of the Critique. But to take of the later ones also ignores the very reason that each one in turn appeared bright for a time and then disappeared. Hegel of course did not disappear but there is at least the one lack that he never solved—that reason has to start somewhere. The best solution to that problem is Fries with the idea of immediate non intuitive knowledge, but besides that Fries is much less impressive than Hegel. [Hegel, is I think the same kind of system as Plotinus, except Plotinus starts with the One and goes down while Hegel starts at the bottom and goes back up until the Absolute Subject.] [And I also must mention that none of the German Idealists saw the importance of John Locke and the Constitution of the USA which was based on him.] The German idealists were best in dealing with philosophical problems, not political problems. [I just noticed an old few ideas I wrote about the system of the USA that I bringg here just forr added context about John Locke. A lot of the USA is based on the Magna Carta and Simon DE Montfort (Provisions of Oxford) and John Locke and the two-tiered parliament system of England. Pluss a lot of the Bill of Rights is based on issues that England had to deal with and resolve that were incorporated in the Bill of Rights of the USA. I might mention that the American Colonists never wanted to separate from England until the King refused intervene in favor of the colonies. The main grievance was toward Parliament. Besides that, there has to be a basic DNA structure in people for them to be able to accept such a system. Unless you have Anglo-Saxon DNA, it is doubtful how well this system could work elsewhere. There is something in the Anglo Saxon DNA which take the written law as absolute and binding. While in the USSR the only reason the system worked at all was the tendency to ignore the written rule and just strive toward what worked]

רב שך סבור שיש רק שני סוגים של חליפין, שווה לשווה, או רכישה באמצעות מטפחת. [לרב שך החלפת מחט בשריון היא שווה בשווה מכיוון שזה רוצה מחט והשני רוצה חליפת שריון.] רב שך סבור שהחליפין חל על נישואין לאישה, ולא על רכישה באמצעות מטפחת. [זה דומה לתוספות ר''יד שסבור שקידושין באמצעות מטפחת שווה יותר מפרוטה שייך לקדש אישה.] לפי זה, עלינו לומר שכאשר רב נחמן אמר בבבא מציעא מ''ו ע''ב ובקידושין כ''ח ע''ב שפרי לא יכול לעשות חליפין, הוא בטח מתכוון שהוא לא יכול ליצור חליפין, אלא שהוא יכול להתקבל באמצעות חליפין. כדי להבהיר את הערתי כאן, הרשו לי להביא כמה נקודות. ראשית, רב שך מדבר רק על הגישה של הרמב''ם. ברור שתוספות ורבינו תם שונים לחלוטין. כמו כן, אנו יודעים שהחוק הוא כמו רב נחמן, שפירות אינם יכולים לבצע חליפין [פירות לא עבדי חליפין], אלא רק כלים.זה לדעת הרמב''ם הלכות מכירה פרק י''ג אבל מהו כלי? עבור תוספות, כלי הוא כל דבר שניתן להשתמש בו. אבל עבור רב שך, זה חייב להתייחס למה שיכול ליצור רכישה, לא למה שניתן לרכוש, משום שהוא סבור שאישה יכולה להרכש על ידי חליפין של שווה לשווה. גישה זו של רב שך, שאני חייב להזכיר, אינה דומה לתוספות, שיש חליפין שווה לשווה, וסוג אחר שאינו שווה לשווה, אך עדיין אינו רכישה על ידי מטפחת או נעל---------- ייתכן שיעזור להבין את מה שרב שך אומר אם אזכיר את ההבהרה של שמואל רוזובסקי שהבעיה היא האם משהו גורם לרכישה כמו במקרה של רכישה באמצעות מטפחת (סודר), או שאין שום מושא שגורם למעבר בכלל. פשוט בהחלפה, אחד רוכש את מושא האדם השני, והשני רוכש את מושא של הראשון. ועדיין, אפילו עם ההבהרה הזו, מוזר שרכישה באמצעות סודר לא תעבוד כדי לקדש אישה למרות שזוהי רכישה מוחלטת באמצעות קניין סודר, בעוד שרכישה באמצעות החלפה תקנה אישה, למרות שזוהי רכישה לא על ידי כסף שטר וביאה. ולפי רב שמואל רוזובסקי חליפין אינו גורם קניין לשני כל אלא כל אחד קונה את החפץ שהוא מגביה. לפי זה אם אחד נותן חפץ לאישה ואומר זה לך ובמקומו את מקודשת לי אין בזה הגבה ומשיכה לאישה. ולהפך אפשר לראות דין של תוספות רי''ד שדווקא קהערה מאוחרת יותר. אני רואה עכשיו שרב שך לומד את רעיון החליפין בצורה שונה מרב שמואל רוזובסקי. הוא אומר שהגישה של הרמב"ם היא שהחלפה שווה בערך שווה היא כמו רכישה במשיכה או הגבהה שבה החפץ הראשון שנלקח הוא שגורם לרכישת החפץ השני, ולכן אין ספק לגבי הגישה של רב שך. הוא מסביר את כל זה בבירור בתחילת הלכות אישותניין סודר עוזר.. ------------------------------------------------לאחר שכתבתי את האמור לעיל, הבנתי שלמעשה זה פתוח ברמב"ם עצמו. בתחילת פרק חמשה בהלכות מכירה הוא טוען שניתן לרכוש פירות על ידי חליפין שווה תחת שוהז-כמו -השאלה שיש לי לגבי גישה זו של הרמב"ם היא שהיא לא נראית מתאימה לגמרא. הגמרא עצמה מדברת תמיד על רכישה באמצעות חליפין ואינה מזכירה אפילו פעם אחת את הגורם לרכישת חליפין. אז מהיכן הרמב"ם היה שואב את גישתו---- עלה בדעתי שהרמב"ם מבין את כל הגמרא כמתייחסת לגרימת רכישה על ידי חליפין---------ההבדל הוא שגרימת רכישה היא תת-קבוצה של היכולת להירכש באמצעות רכישה. זה כמו העובדה שהחלפת כסף אינה גורמת לרכישה. רק משיכה או הרמה יכולים לגרום לרכישה. לכן, אנו רואים שהרמב"ם מבין את הגמרא כמתייחסת לגרימת רכישה------ ם זאת, עליי לציין שסוגיה זו היא ויכוח בין תוספות לרמב"ם, משום שתוספות מקפיד להראות כיצד כל הנושא מתייחס ליכולת להירכש באמצעות חליפין. הוא מסביר שהמשנה, שנשמעת כאילו פירושה גרימת רכישת מטבע באמצעות חליפין של חפץ, פירושה שמטבע לעולם לא ניתן לרכוש באמצעות חליפין. ניתן לרכוש אותו רק באמצעות מכירה. אם אדם מחליף חפץ בכספו של אחר, כסף זה אינו נרכש. ניתן לרכוש אותו רק אם הוא משמש לקניית החפץם זאת, עליי לציין שסוגיה זו היא ויכוח בין תוספות לרמב"ם, משום שתוספות מקפיד להראות כיצד כל הנושא מתייחס ליכולת להירכש באמצעות חליפין. הוא מסביר שהמשנה, שנשמעת כאילו פירושה גרימת רכישת מטבע באמצעות חליפין של חפץ, פירושה שמטבע לעולם לא ניתן לרכוש באמצעות חליפין. ניתן לרכוש אותו רק באמצעות מכירה. אם אדם מחליף חפץ בכספו של אחר, כסף זה אינו נרכש. ניתן לרכוש אותו רק אם הוא משמש לקניית החפץ---------------------יש לציין כאן שרש''י ותוספות לומדים את הוויכוח בין רב נחמן לרב ששת באופן שונה מהרמב''ם. עד כה אמרתי שלפי הרמב''ם, החוק רב נחמן הוא שפירות ניתנים לרכישה על ידי חליפין, אך אינם יכולים לבצע חליפין; בעוד שלרב ששת הם יכולים גם לגרום לחליפין. לפי רש''י הם (רב נחמן ורב ששת) נבדלים בכך. רב ששת קובע שכל החפצים המטלטלים ניתנים לרכישה על ידי חליפין ולגרום גם להם. עבור רב נחמן רק כלים שניתן להשתמש בהם ניתנים לרכישה על ידי חליפין ולגרום לחליפין. עבור רש''י, שור או פרה נחשבים כנכללים בחפצים המטלטלים. רב נחמן התכוון להוציא רק פירות ממה שיכול לגרום לחליפין, אך חוץ מזה, כל החפצים המטלטלים יכולים לגרום לחליפין, או אולי רק כלים שמישים. אבל הרמב''ם כותב, "אפשר להחליף כלים בכלים, בהמה בבהמה, אפילו מחט בשריון או טלה בסוס, אבל אם הוא מחליף פרי בפרי, ניתן להחיל על כך את חוק המרמה." (אם ההחלפה הייתה יותר מחמישית מערכה, ההחלפה בטלה). האם טלה ניתן לשימוש ככלי או כמו חפצים ניידים אחרים? אני מתכוון שהוא אולי מתכוון שרק כלים יכולים לגרום להחלפה והוא אולי יטען שטלה כלול, או שאולי הוא מתכוון שכל החפצים הניידים מלבד פרי יכולים לגרום להחלפה

Bava Metzia 46

Rav Shach (laws of marriage 1:2)holds that there are only two types of exchange, equal to equal, or acquisition by a handkerchief. [To Rav Shach exchange of a needle for a suit of armor is equal to equal since this one wants a needle and the other wants a suit of armor.] Rav Shach holds the exchange is applicable to marrying a woman, not the acquisition by a handkerchief. ([This is like the Tosphot R'id who holds acquisition by handkerchief that is worth more that a pruta can acquire a wife.])According to this, we must say that when Rav Nachman said in Bava Metzia 46 and Kidushin 28b that fruit can not make an exchange, he must mean it cannot create an exchange but that it can be acquired by exchange. To make my comment here clear let me bring a few points. First Rav Shach is only talking about the approach of the Rambam. Clearly, Tosphot and Rabbainu Tam are utterly different. Also, we know the law is like Rav Nachman that fruit can not make an exchange, but rather only vessels. (Rambam laws of sale chapter 13) But what is a vessel? To Tosphot, a vessel is anything that can be used. But to Rav Shach this must mean that which can create an acquisition, not that which can be acquired because he holds a woman can be acquired by exchange of equal to equal. This approach of Rav Shach I must mention is not like Tosphot that there is exchange equal to equal, and a different kind that is not equal to equal, but is still not acquisition by handkerchief nor shoe. It might help to understand what Rav Shach is saying if I mention the clarification of Shmuel Rozovski that the issue is if something causes a acquisition as in the case of acquisition by a handkerchief, or if there is no object causing the transition at all. Simply in the exchange one acquires the object of the other person, and the other acquires the object of the first person. Still even with this clarification it is odd that acquisition by handkerchief would not work to marry a wife even though it is absolutely acquisition by money while acquisition by pure exchange would acquire a woman though it is a different kind of acquisition. (Later note.) I see now that Rav Shach learns the idea of exchange different than Rav Shmuel Rosovsky. He says that the approach of the Rambam is that exchange equal value for equal value is still like an acquisition by money in which the first object tat is picked up is what causes the second object to be acquired and therefore there is no question about the approach of Rav Shach. He explains this all clearly in the beginning of laws of marriage After writing the above, it occurred to me that in fact this is open in the Rambam himself. In the beginning of chapter five in laws of sale he holds that fruit can be acquired by exchange equal for equal just like Rabbainu Tam. So, when he holds like Rav Nachman that “fruit cannot make exchange,” that has to mean it cannot cause an acquisition of exchange, but they can be acquired by exchange. The question I have on this approach of the Rambam is that it does not seem to fit with the Gemara. the Gemara itself is talking always about being acquired by exchange and never once mentions causing an acquisition of exchange. So, from where would the Rambam have derived his approach?It occurred to me that the rambam understands the entire gemara as referring to causing acquisition by exchange[The difference is that causing acquisition is a subset of being able to be acquired by acquisition. This is like the fact that exchange of money does not cause acquisition. Only pulling or picking up can cause acquisition. Therefore, we see the Rambam understands the Gemara to be referring to causing acquisition.] However, I might mention that this issue is a debate between Tosphot and the Rambam because Tosphot makes a point of showing how the whole subject is referring to the ability to be acquired by exchange. He explains that the Mishna that sounds like it means causing acquisition of a coin by means of exchange of an object means that a coin can never be acquired by exchange. It can only be acquired by a sale. If one exchanges an object for the money of another, that money is not acquired. It can only be acquired if it is used to buy the object. I might mention here that Rashi and Tosphot learn the argument between Rav Nachman and Rav Sheshet differently than the Rambam. So far I have been saying according to the Rambam, the law of Rav Nachman is that fruit can be acquired by exchange, but can not make exchange; while to Rav Sheshet they can also cause exchange. According to Rashi, they differ in this. Rav Sheshet holds all movable objects can be acquired by exchange and cause it also. to Rav Nachman only vessels, that can be used can be acquired by exchange .and cause exchange. To Rashi, a ox or cow are considered to be included in movable objects. Rav Nachman mean to exclude only fruit in what can not cause exchange, but besides that, all movable objects can cause exchange, or maybe only usable vessels. However, the Rambam writes, ” One can exchange vessels for vessels, an animal for an animal, even a needle for a coat of armor or a sheep for a horse, but if he exchanges fruit for fruit , that can have the law of cheating applied to it.” (If the exchange was more than a fifth of its value, the exchange is nullified). Is a sheep usable like a vessel or like other movable objects? I mean to say he might mean that only vessels can cause exchange and he might hold thanot a sheep is included, or perhaps he means all movable objects besides can cause exchange but just not fruit? now i would like to add here that ------------------------------------------------------------------------------------------------------------------------------------- [laws of marriage 1:2] holds that there are only two types of exchange, equal to equal, or acquisition by a handkerchief. [To רב שךexchange of a needle for a שריון is equal to equal since this one wants a needle and the other wants a suit of שריון.] רב שךholds the exchange is applicable to marrying a woman, not the acquisition by a handkerchief. According to this, we must say that when רב נחמן said in בבא מציעא מ''ו ע''ב and קידושין כ''ח ע''ב that fruit can not make an exchange, he must mean it cannot create an exchange but that it can be acquired by exchange. To make my comment here clear let me bring a few points. First רב שךis only talking about the approach of the רמב''ם. Clearly, תוספות and רבינו תם are utterly different. Also, we know the law is like רב נחמן that fruit can not make an exchange, but rather only vessels. But what is a vessel? To תוספות, a vessel is anything that can be used. But to רב שך this must mean that which can create an acquisition, not that which can be acquired because he holds a woman can be acquired by exchange of equal to equal. This approach of רב שךI must mention is not like תוספות that there is exchange equal to equal, and a different kind that is not equal to equal, but is still not acquisition by handkerchief nor shoe. After writing the above, it occurred to me that in fact this is open in the רמב''ם himself. In the beginning of chapter five in הלכות מכירה he holds that fruit can be acquired by exchange equal for equal just like ר' תם. So, when he holds like רב נחמן that “fruit cannot make exchange,” that has to mean it cannot cause an acquisition of exchange, but they can be acquired bהThe question I have on this approach of the רמב''ם is that it does not seem to fit with the גמרא. Theגמרא itself is talking always about being acquired by exchange and never once mentions causing an acquisition of exchange. So, from where would the רמב''ם have derived his approach?y exchange. [The difference is that causing acquisition is a subset of being able to be acquired by acquisition. This is like the fact that exchange of money does not cause acquisition. Only pulling or picking up can cause acquisition. Therefore, we see the רמב''ם understands the גמרא to be referring to causing acquisition. However, I might mention that this issue is a debate between תוספות and the רמב''ם because תוספות makes a point of showing how the whole subject is referring to the ability to be acquired by exchange. He explains that the משנהthat sounds like it means causing acquisition of a coin by means of exchange of an object means that a coin can never be acquired by exchange. It can only be acquired by a sale. If one exchanges an object for the money of another, that money is not acquired. It can only be acquired if it is used to buy the object.---------I might mention here that רש''יand תוספות learn the argument between רב נחמן and רב ששתdifferently than the רמב''ם. So far I have been saying according to the רמב''ם , the law of רב נחמן is that fruit can be acquired by exchange, but can not make exchange; while to רב ששת they can also cause exchange. According to רש''י they differ in this. רב ששת holds all movable objects can be acquired by exchange and cause it also. to רב נחמן only vessels, that can be used can be acquired by exchange .and cause exchange. To רש''י , a ox or cow are considered to be included in movable objects. רב נחמן meant to exclude only fruit in what can not cause exchange, but besides that, all movable objects can cause exchange, or maybe only usable vessels. He writes, ” One can exchange vessels for vessels, an animal for an animal, even a needle for a coat of armor or a sheep for a horse, but if he exchanges fruit for fruit , that can have the law of cheating applied to it.” (If the exchange was more than a fifth of its value, the exchange is nullified). Is a sheep usable like a vessel or like other movable objects? I mean to say he might mean that only vessels can cause exchange and he might hold that a sheep is included, or perhaps he means all movable objects besides can cause exchange but just not fruit?

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