בבא מציעא דף מ''ו ע''ב. תוספות - המילים הראשונות ולרב נחמן". בקיצור, רבינו תם קובע כי פירות שווים גורמים או נרכשים על ידי חליפין. תוספות שואלים על כך מן הגמרא. הגמרא אומרת שאם מטבע יכול לשמש להחלפה, וזו תהיה כוונת המשנה "כל מה שנעשה כסף עבור אחר", ברגע שאחד רוכש, גם השני רוכש. אז למה יכול להתייחס סוף המשנה, המתייחס להחלפה של שתי חיות? אחרי הכל, אין כאן מטבע. הגמרא עונה שסוף המשנה ואומרת לנו שניתן להשתמש בפירות כהחלפה. הגמרא שואלת על כך והלא רב נחמן מחזיק בפירות, שלא ניתן להשתמש בהם להחלפה. התשובה של תוספות יכולה להיות שהמשנה מתייחסת למקרה של שווה תחת שווה. תוספות עונה שהמשנה אינה מתייחסת למקרה של שווה תחת שווה. אבל תוספות מרחיק לכת ואומר שאפילו בדרך שבה רב יהודה מבין את המשנה, זה גם לא מתייחס לשווה בשביל שווה. אבל השאלה על זה היא למה בכלל להזכיר את רב יהודה? למה זה יהיה נחוץ בכלל? הרי השאלה הייתה רק על רב נחמן. הסתפקנו בתשובת רב יהודה הייתי בים ועלה בדעתי מדוע תוספות מעלה את הרעיון שאפילו אם נלמד את המשנה כ"כל הנישום", זה עדיין לא שווה תמורת שווה. אני חושב שהסיבה היא שאם חליפין עובד בעבור תמורת פירות כאשר הערך הכספי של כל אחד שווה תמורת שווה, אז אפילו רב יהודה לא היה צריך לבוא על התשובה "כל הנישום". הוא היה יכול לומר ש"כל הנעשה" יכול להתייחס לפירות ולכל החפצים הנעים כאשר זה שווה תמורת שווה. עם זאת, אני חייב לציין שיש ויכוח בין המהרש"א למהר"ם שיף לגבי מה התכוונו תוספות לומר כשהוא מעלה את תשובתו של רב יהודה. שתי התשובות נראות לי סבירות, אולם אני חושב שהתשובה שלי היא פשוטה יותר. כלומר, אם רבינו תם היה צודק והמשנה הייתה יכולה להיות שווה תחת שווה, אז רב יהודה לא היה צריך להגיע לתשובה קשה לגבי המשנה כאשר תשובה פשוטה יותר הייתה זמינה

Bava Mezia page 46b. Tosphot first words and to Rav Nachman”. In short, Rabainu Tam holds equal for equal works to cause or to be acquired by exchange even for fruit. Tosphot asks on this from the Gemara. The Gemara says if coin can be used for exchange, and that would be the intension of the Mishna “all that is made money for another”, once one acquires, the other also acquires. Then what could the end of the Mishna which refers to exchange of two animals be referring to. After tall, there is no coin here. The gemara aanswers the end of the Mishna tell us fruit can be used in exchange. The Gemara asks on this from Rav Nachman who holds fruit cannot be used for exchange. The answer could be that the Mishna is referring to a case of equal for equal. Tosphot answers the Mishna is not refering to a case of equal for equal. But Tosphot goes further and says even in the way Rav Judah understands the Mishna, it is also not referring to equal for equal. But the question on this is why mention Rav Judah at all? Why would this be necessary at all? After all the question was only on Rav Nachman. We were satisfied with the answer of Rav Judah. I was at the sea and it occurred to me why tosphot brings up the idea that even if we learn the Mishna as "all that is evaluated" it still is not equal for equal. I think the reason is that if exchange works for fruit when the monetary worth of each is equal for equal then even rav judah would not have had to come onto the answer for "all that is evaluated". He could have said all that is made could refer to fruit and all movable objects when it is equal for equal. however, I must mention that there is an argument between the Maharsha and the Maharam Shif about what Tosphot means to say by bring up the answer of Rav Judah. Both answers seem reasonable to me however I think my answer is simpler. that is if Rabainu Tam would be right then Rav Judah would not have had to come onto difficult answer about the mishna when a simpler one was available.-----------------------------------------------------------------------------בבא מציעא page מ''ו ע''ב. תוספותfirst words and to רב נחמן”. I was at the sea and it occurred to me why תוספותbrings up the idea that even if we learn the משנה as "כל הנישום" it still is not equal for equal. I think the reason is that if exchange works for fruit when the monetary worth of each is equal for equalת then even רב יהודהwould not have had to come onto the answer כל הנישום . He could have said "כל הנעשה" could refer to fruit and all movable objects when it is equal for equal. However, I must mention that there is an argument between the מהרש''א and the מהר''ם שיף about what תוספות means to say by bring up the answer of רב יהודה. Both answers seem reasonable to me, however I think my answer is simpler. That is, if רבינו תם would be right and the משנה could be a case of equal for equal, then רב יהודה would not have had to come onto difficult answer about the משנה when a simpler one was available. in short rabainu tam holds qequal for equal works to cause or to be acquired by exchange even for fruit. tosphot asks on this from the gemara. the gemara says if coin can be used for exchange and that would be the intension of the mishna all that is made monney for another, once one acquires the other also acquires. then what could the end of the mishna which refers to exchange of two anumals be refering to. after tall, there is no coin here. answer the end tell us fruit can be used in exchange. the gemara asks ogfn this from rav nachma who holds friuit canot be used for exchange. the answer could be that the mishna is refering to a case of equal for equal. tosphot answrs the mishna is not refer to a case of equal for equal. but tosphot goes further and says even in the way rav juda understands the mishna, it is also not refering to equal for equal. why would this be neccessary at all? after all the question was only on rav nachman. we were satisfied with the answer of rav juday.----------------- In short, רבינו תם holds equal for equal works to cause or to be acquired by exchange even for fruit. תוספותasks on this from the גמרא. The גמרא says if coin can be used for exchange, and that would be the intension of the משנה “all that is made money for another”, once one acquires, the other also acquires. Then what could the end of the משנה which refers to exchange of two animals be referring to. After tall, there is no coin here. The גמרא answers the end of the משנה tell us fruit can be used in exchange. The גמרא asks on this from רב נחמן who holds fruit cannot be used for exchange. The answer could be that the משנה is referring to a case of equal for equal. תוספות answers the משנה is not referring to a case of equal for equal. But תוספות goes further and says even in the way רב יהודה understands the משנה , it is also not referring to equal for equal. But the question on this is why mention רב יהודה at all? Why would this be necessary at all? After all the question was only on רב נחמן. We were satisfied with the answer of רב יהודה.

ברמב"ם הלכות מכירה פרק ה' הוא מביא את חוק החליפין. אבל במקרה של רכישה בכסף בפרק א' הוא לא מביא את חוק החליפין. נראה מכך שהחלפת חפצים אינה רכישה בכסף. למרות שמה שיש לו ערך כספי נחשב לפעמים ככסף, עדיין ישנם מקרים שבהם זה לא כך, למשל פדיון עבד עברי צריך להיות באמצעות כסף, לא מה ששווה כסף. דוגמאות נוספות הן בדיני גניבה שבהן יש ויכוח האם אפשר לשלם במה שיש לו ערך כספי. לכן, כאשר הגמרא אומרת שאי אפשר לשאת אישה בהחלפה, פירוש הדבר החלפה בכלים כמו מטפחת, לא החלפה שווה תחת שווה. כאן אני רק מזכיר בקצרה את מה שאומר רב שך בתחילת חוקי אישות

In the Rambam laws of sale chapter 5 he brings the law of exchange. but in the case of acquisition by money in chapter 1 he does not bring the law of exchange. It seems clear from this that exchange of objects is not acquisition by money. Even though that which has monetary value is sometimes considered to be like money, still there are cases where it is not, for example the redemption of a Jewish slave has to be through money, not that which is worth money. Other examples are in laws of theft where there is an argument if one can pay by that which has monetary value. So when the Gemara says one cannot marry a wife by exchange that means exchange by vessels like a handkerchief, not exchange equal for equal. Here I am just mentioning in short what Rav Shach says in the beginning of laws of marriage.------------------------------------------------------------------------------------------------------------------- In the רמב''ם הלכות מכירה פרק ה' 5 he brings the law of exchange. But in the case of acquisition by money in chapter א' he does not bring the law of exchange. It seems clear from this that exchange of objects is not acquisition by money. Even though that which has monetary value is sometimes considered to be like money, still there are cases where it is not, for example the redemption of a Jewish slave has to be through money, not that which is worth money. Other examples are in laws of theft where there is an argument if one can pay by that which has monetary value. So when the גמרא says one cannot marry a wife by exchange that means exchange by vessels like a handkerchief, not exchange equal for equal. Here I am just mentioning in short what רב שך says in the beginning of laws of marriage.

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