165 - Neither the Time Nor the Place: Hasdai Crescas

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Ḥasdai Crescas shows Aristotelian physics who’s boss, by defending alternative conceptions of time, place and infinity.



Further Reading

• R. Weiss (trans.), Ḥasdai Crescas: Light of the Lord (Or Hashem) (Oxford: 2018).


• R. Glasner, “Gersonides on Simple and Composite Motion,” Studies in History and Philosophy of Science 27 (1996), 545-84.

• W.Z. Harvey, Physics and Metaphysics in asdai Crescas (Amsterdam: 1998).

• H. Maccoby, “Crescas’s Concept of Time,” in G. Jarity and G. Moreno-Riano (eds), Time and Eternity: The Medieval Discourse (Turnhout: 2003), 163-70.

• T. Rudavsky, “The Theory of Time in Maimonides and Crescas,” Maimonidean Studies (1990), 143-62.

• H.A. Wolfson, Crescas’ Critique of Aristotle (Cambridge MA: 1929).

Stanford Encyclopedia: Hasdai Crescas


Maciek Zajac on 2 March 2014

Mad props!


You most probably do not realize this but You are effectively lecturer of ancient philosophy at the University of Warsaw, Poland, with many students choosing to listen to Your podcasts (in our giraffe-containing zoo, for example) instead of going to more traditional lectures. This is the best learning tool ever, able to interest hardcore analytic philosophy fans in the intricacies of jewish legal scholarship, which speaks volumes.

Still, I personally believe that with this kind of voice You have a duty to quit philosophy and became a radio personality full-time.

In reply to by Maciek Zajac

Peter Adamson on 3 March 2014

HoPWaG in Warsaw

Wow, thanks! I am really glad that the podcast is finding an appreciative audience in Poland.

In reply to by Peter Adamson

Lord Taco on 16 April 2014


Be careful! If you convince him to quit his position in philosophy, the first thing he will do is become the giraffe caretaker at the zoo!

Berel Dov Lerner on 3 March 2014

13 Principles in Mishneh Torah?

In your latest podcast you said that Maimonides' 13 principles of faith are listed both in his Mishneh Torah as well as in his Commentary on the Mishnah. I'm pretty sure that a list of the 13 principles appears *only* in the Commentary on the Mishnah ("Introduction to the Chapter Helek").

In reply to by Berel Dov Lerner

Peter Adamson on 3 March 2014

13 principles

Thanks, I'll double check that. I am pretty sure that Kellner mentions the principles appearing in both texts, but if not I will fix this for the book version.

In reply to by Peter Adamson

benAvram on 5 March 2014

13 principles

They are listed in Hilkhoth Teshuvah 3:6-8 as legal requirements, but not as neatly as in Pereq Heleq. It's also not specific to principles of faith, but also actions that result in losing a share in the world to come. I wouldn't say it's inaccurate to state that the principles also appear in the Mishneh Torah, but you're not going to find the same 13 enumerated principles in the same place at the exclusion of other core Jewish beliefs dogmas.

In reply to by benAvram

Peter Adamson on 6 March 2014

13 principles

Great, thanks! That's very helpful.


In reply to by Peter Adamson

benAvram on 6 March 2014

13 principles

No problem. Glad I could contribute in some small way as a modest thank you for your efforts. You've made my commute and dog walks much more enjoyable and productive, and I'm excited for your take on the development of kabbalah. Keep up the good work!

In reply to by benAvram

Berel Dov Lerner on 8 March 2014


But where do you see a parallel to the 11th principle - divine reward and punishment - in the section from Hilkhot Teshuva?

In reply to by Berel Dov Lerner

benAvram on 9 March 2014

13 Principles

Besides the rewards and punishments listed in the MT halakhic cited, the rewards and punishments are included in the law of the Torah. The denial of the consequences of the law is at least conceptually severable from denying the divinity and the immutableness (word?) of the law.

In reply to by benAvram

Berel Dov Lerner on 9 March 2014

I have copied the relevant

I have copied the relevant section from the MT (translation from the CHABAD website)below and I ask: What phrase here parallels the principle of divine reward and punishment? I'm not sure what you meant by "the rewards and punishments are included in the law of the Torah" - if you were talking about Hilkhot Yesodei HaTorah (which, after all, does contain a lot of philosophical material)then again I ask : where do you find reward and punishment there? I just skimmed over it all and I may very well have missed something, but it seems to me that the closest it comes to talking about reward and punishment is in 10:4 which discusses the reliability of a prophet whose prophecy of future punishment is not fulfilled, but that can hardly be said to restate the principle of faith.

Halacha 6

The following individuals do not have a portion in the world to come. Rather, their [souls] are cut off and they are judged for their great wickedness and sins, forever:

the Minim,

the Epicursim,

those who deny the Torah,

those who deny the resurrection of the dead and the coming of the [Messianic] redeemer,

those who rebel [against God],

those who cause the many to sin,

those who separate themselves from the community,

those who proudly commit sins in public as Jehoyakim did,

those who betray Jews to gentile authorities,

those who cast fear upon the people for reasons other than the service of God,



one who extends his foreskin [so as not to appear circumcised].
Halacha 7

Five individuals are described as Minim:

a) one who says there is no God nor ruler of the world;

b) one who accepts the concept of a ruler, but maintains that there are two or more;

c) one who accepts that there is one Master [of the world], but maintains that He has a body or form;

d) one who maintains that He was not the sole First Being and Creator of all existence;

e) one who serves a star, constellation, or other entity so that it will serve as an intermediary between him and the eternal Lord.

Each of these five individuals is a Min.
Halacha 8

Three individuals are described as Epicursim:

a) one who denies the existence of prophecy and maintains that there is no knowledge communicated from God to the hearts of men;

b) one who disputes the prophecy of Moses, our teacher;'

c) one who maintains that the Creator is not aware of the deeds of men.

Each of these three individuals is an Epicurus.

There are three individuals who are considered as one "who denies the Torah":

a) one who says Torah, even one verse or one word, is not from God. If he says: "Moses made these statements independently," he is denying the Torah.

b) one who denies the Torah's interpretation, the oral law, or disputes [the authority of] its spokesmen as did Tzadok and Beitus.

c) one who says that though the Torah came from God, the Creator has replaced one mitzvah with another one and nullified the original Torah, like the Arabs [and the Christians].

Each of these three individuals is considered as one who denies the Torah.

רמב"ם יד החזקה - הלכות תשובה פרק ג
(ו) ואלו הן שאין להן חלק לעולם הבא אלא נכרתים ואובדין ונידונין על גודל רשעם וחטאתם לעולם ולעולמי עולמים המינים והאפיקורוסין והכופרים בתורה והכופרים בתחיית המתים ובביאת הגואל המורדים ומחטיאי הרבים והפורשין מדרכי צבור והעושה עבירות ביד רמה בפרהסיא כיהויקים והמוסרים ומטילי אימה על הצבור שלא לשם שמים ושופכי דמים ובעלי לשון הרע והמושך ערלתו:
(ז) חמשה הן הנקראים מינים האומר שאין שם אלוה ואין לעולם מנהיג והאומר שיש שם מנהיג אבל הן שנים או יותר והאומר שיש שם רבון אחד אבל שהוא גוף ובעל תמונה וכן האומר שאינו לבדו הראשון וצור לכל וכן העובד כוכב או מזל וזולתו כדי להיות מליץ בינו ובין רבון העולמים כל אחד מחמשה אלו הוא מין. [השגת הראב"ד - והאומר שיש שם רבון אחד אלא שהוא גוף ובעל תמונה א"א ולמה קרא לזה מין וכמה גדולים וטובים ממנו הלכו בזו המחשבה לפי מה שראו במקראות ויותר ממה שראו בדברי האגדות המשבשות את הדעות]. [השגת הראב"ד - וכן האומר שאינו לבדו הראשון א"א כאותו שאמר אלהיכם צייר גדול היה אלא שמצא לו סמנים גדולים תהו ובהו חושך ומים ורוח ובהם עשה מה שעשה]:

(ח) שלשה הן הנקראים אפיקורסין האומר שאין שם נבואה כלל ואין שם מדע שמגיע מהבורא ללב בני האדם והמכחיש נבואתו של משה רבינו והאומר שאין הבורא יודע מעשה בני האדם כל אחד משלשה אלו הן אפיקורוסים שלשה הן הכופרים בתורה האומר שאין התורה מעם ה' אפילו פסוק אחד אפילו תיבה אחת אם אמר משה אמרו מפי עצמו הרי זה כופר בתורה וכן הכופר בפרושה והוא תורה שבעל פה והמכחיש מגידיה כגון צדוק ובייתוס והאומר שהבורא החליף מצוה זו במצוה אחרת וכבר בטלה תורה זו אע"פ שהיא היתה מעם ה' כגון ההגרים כל אחד משלשה אלו כופר בתורה:

In reply to by Berel Dov Lerner

benAvram on 9 March 2014

reward and punishment

For one, I did say it's not as neat, but it is there conceptually. For starters, consider that the first line you posted is a punishment. If you don't believe, then you don't get a share in the world to come. Furthermore, if you deny a single line of the Torah, you are an apikoros. That includes "that you may live long in the land," a reward. Then consider that the oral law is included. The oral law contains within it mandatory beliefs and actions, prohibitions, and their consequences. If you deny there is consequence to the oral law, you are an apikoros.

In reply to by benAvram

Berel Dov Lerner on 9 March 2014

My original complaint was

My original complaint was that the 13 Principles are not actually listed in the MT. It's pretty obvious that a numbered list of the actual principles (or an essay enumerating principles, as in Helek) appears nowhere in the MT, and, for that matter, if Maimonides were interested in proclaiming such a list, the logical place to do it would have been in Hilkhot Yesodei HaTorah. I appreciate your drash, but obviously the warning of punishment is not part of the actual list of prescribed beliefs. I don't have anything relevant by Menachem Kellner ready to hand (he told me he might weigh in on this issue later with a comment of his own) but consider what Herbert Davidson wrote on pg. 157 of his *Moses Maimonides: the Man and his Works*: "Of the thirteen principles in the present list [Helek] twelve appear in Maimonides' Mishneh Torah, but they do so in a different guise." In footnote 133 on that page he writes: "Maimonides seems to have overlooked the eleventh of the thirteen principles: reward and punishment..."

In reply to by Berel Dov Lerner

benAvram on 9 March 2014

13 Principles

Well, I can quote myself on this "I wouldn't say it's inaccurate to state that the principles also appear in the Mishneh Torah, but you're not going to find the same 13 enumerated principles in the same place at the exclusion of other core Jewish beliefs dogmas." As per your quoted scholar, I respectfully disagree, and I'm going to identify his mistake as conflating a law code with a pedagogical text. A law can be black and white in function if not explicit in text. I demonstrated that one would be in breach of the law if you deny reward and punishment. Therefore, it's prohibited by the cited halakhoth if not explicitly so. Pereq Heleq is a pedagogical text, its purpose is to teach correct belief and therefore the text should be explicit in what you believe. The purpose of the MT is to evaluate beliefs for heresy, again which I demonstrated it does on this point.

paul on 7 March 2014

Thanks for this chap.

I must admit I did not think I would be so interested in Hasdai Crescas. However, he joins a few others, Al-Razi and John Philoponus, that you have introduced me to that I would ignored if not introduced to them through the pod cast. So, thank you. One thing that has fascinated me about these three is they are coming out from a devoutly monotheistic background. We all tip our hats to the likes of Aristotle, Avicenna and recognise their worth but these chaps are not afraid to take on anyone. These are not romantic rebels either. It makes me wonder why their background in their respective religions could give such insights and yet the materialists are not providing as much. It cannot just be simple repression.

In reply to by paul

Peter Adamson on 7 March 2014


Yes he's good, isn't he? I'm just writing a script for a future podcast about Abu l-Barakat al-Baghdadi, a Jewish convert to Islam who had some similar ideas to Razi and Crescas. So you will probably like him too! He'll be episode 172.

Bear on 8 March 2014


Crescas is a fascinating character, and a good illustration of the complexities of life in the middle ages.

One of the common aspect of all Abrahamic religions is none recognise apostasy - apostates are treated as bad Jews, Christians or Muslims: the Christian view being confirmed since the resolution of the Donatist controversy.

Thus, Crescas is pious in exhorting the Conversi to return to the practice of Judaism. Although Crescas is a non-Christian living in a country ruled by Christian monarchs, he is able to publish books which are deeply offensive to Christians, and urging a particular group of Christian to apostatise, and suffer no official sanction.

The same would not be true of the Conversi, if they were convinced of his arguments and returned to the practice of Judaism. Since they had been baptised, they would have been considered Christians, and therefore subject to ecclesiastical sanctions - and later, the attention of the Spanish Inquisition.

Bear on 8 March 2014

Aristotle and Modern Science

A comment made in passing about the need to destroy Aristotle to found modern empirical science is misplaced.

At school, Aristotle was portrayed to be an almost demonic figure who set back science millennia, and that if one read Aristotle the mind would rot: and taking Aristotle seriously is knavery.

Unfortunately this is a common view of the relationship between Aristotle and science. Roger Penrose, however, has a much more balanced view of Aristotle. He indicates that Aristotle's Physics was limited by the information and models that he had to hand.

I would argue that it was in the introduction of Aristotle into Western Europe in the 11th and 12th centuries that allowed the development of modern science due its emphasis on observation and experimentation. Figures such as Roger Bacon and Robert Grosseteste were both part of an early experimentalist movement, which lead to the methods used by Galileo and other 16th century scientists.

The modern scientific method did not emerge like Athena fully formed from the head of Galileo.

In reply to by Bear

Peter Adamson on 8 March 2014

Aristotle the bad guy

Thanks for your interesting comments on this episode. As I guess you'll know if you are a regular listener, no one can outdo me when it comes to admiration for Aristotle! (I think he is the greatest philosopher of all time, by pretty much any measure, insofar as it makes sense to pick someone for that title.) And you're definitely right that careful engagement with Aristotle is going on right through the development of modern science, it isn't like they just chuck him out the window and start over, even when they claim to be doing that (as with Descartes). However I do think that this engagement often took the form of detailed critique, and that is just what we see with Crescas. So what I was trying to say was that in this case at least, positive progress was made in the context of a negative project, in other words he puts forward interesting (and in some cases true) hypotheses in physics as possibilities that have not been ruled out by Aristotle and his heirs.

In reply to by Peter Adamson

Bear on 9 March 2014

the bad guys...

I stand corrected. A thoughtful and intelligent critique of Aristotle certainly drove modern science, and I can see that this is what Crescas is doing.

A modern tendency is to accept the Kuhnian "paradigm shift" in regards to modern science - particularly Physics. This means dismissing rather engaging with earlier works in the discipline.

One observation - Crescas did not attack Aristotelian biology. This is one area in which Aristotle survived to the modern era. I seem to recall that even in the late 19th century, scientists were debating the theory of spontaneous generation. Louis Pasteur had a hand in finally refuting this theory.

In reply to by Bear

Peter Adamson on 10 March 2014


Yes, great point that Aristotelian biology is one of the factors in his influence on later science. It's interesting that it doesn't seem to have captured the attention of late Greek commentators, but in the Arabic tradition they do engage with it (for instance Avicenna wrote about animals). I'm actually in the early stages of editing a book on animals in the history of philosophy so I will be thinking a lot about this in the next couple of years.

Stilgar on 6 May 2015

Crescas and the theory of Impetus

Concerning the motion of stars (boy, do I like stars), you mentioned that Crescas did not think an object in void would slow down, since it is not moving through a medium. This seems more innovative than you gave it credit for? This seems constructive. I did not think Aristotelian theories of motion were cast aside until John Buridan posited the theory of Impetus. Did Crescas actively posit such a theory?

In reply to by Stilgar

Peter Adamson on 7 May 2015


My memories on Crescas are slightly vague but, although you are right that this is big news, there are three caveats. First, the idea already appears in Philoponus and Ibn Bajja, as I mentioned. Second, bear in mind this is all in the context of Crescase raising doubts about the Aristotelian system, not putting forward his own system. And third - this is the important one - I believe that this is not quite the same as Buridan's impetus theory. Rather, as in Philoponus (and some 13th century Latin medieval physicists I'm talking about in an episode coming up in just a few weeks, actually, like Richard Rufus) the idea is that an impressed power is put into the moved object by the mover. This power is only impaired by the medium, and this part is right. But I think Crescas also assumes that even in a void the object would slow down and stop at some point, when the impressed power "runs out", as opposed to continuing forever in the absence of resistance. So that's why I put it as I did in the episode ("the effect of a dense medium is only to slow down a motion’s intrinsic speed. In a void, there would be no slowing effect at all, so the speed would be determined solely by the motion’s impetus. But of course this speed will remain finite").

In reply to by Stilgar

Zarl on 18 April 2019

Crescas and Buridan

It should also be pointed out that Crescas is posterior to Buridan. To be exact, Crescas was 18 years old at the time of Buridan's death.

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