Are there really such thing as sheidim? If so, what are they? Please include sources.
Unless we assume it is all allegory, the Talmud is replete with references to Mazikin, aka Sheidim, and they sure sound real.
Rabbis even had conversations with them (e.g. Chullin 105b), provided a way to see them (Berachot 6a), overheard them (Succa 28a) and established laws based on their existence (e.g. Berachot 3b and Pesachim 100b).
Abaye decreed upon the Mazikin that they should no longer bother us, which may explain why we don't know much about their existence today.
The gemara clearly mentions sheidim, and there were certainly Rishonim (e.g. Rashi) and Acharonim who took these mentions literally.
The Rambam takes them non-literally, as he writes in Moreh Nevuchim 1:7 and in his perush haMishnayot to Avodah Zarah 4:7.
The Kotzker Rebbe has a famous elu veElu in which he explains that the Rambam effectively paskened sheidim out of existence. However, if one looks at the actual words of the Rambam, it seems rather unlikely that the Rambam would agree to this harmonization.
I discuss this in depth, giving the text of the actual sources, in this parshablog post: http://parsha.blogspot.com/2010/10/demons-on-ark-and-kotzkers-famous-elu.html
The straightandforward understanding of Chazal is that there are sheidim and that they are a troublemaking species which are somewhat physical, somewhat spiritual.
Our Rabbis taught: Six things are said concerning demons: in regard to three, they are like the ministering angels; and in regard to three like human beings.‘In regard to three they are like ministering angels’: they have wings like ministering angels; and they fly from one end of the world to on the other like ministering angels; and they…hear from behind the Veil like ministering angels. ‘And in regard to three, they are like human beings’: they eat and drink like human beings, they propagate like human beings, and they die like human beings. (Hagigah 16a, Traditional Press)
Our Rabbis taught: there are three reasons why one must not go into a ruin: because of suspicion, of falling debris and of demons [sheidim]… To one [person] an evil spirit may show itself and harm him; to two it may show itself, but without harming them; to three it will not even show itself (Berakoth 3a, 43b, Traditional Press, New York City New York, translated by Maurice Simon, M.A., edited by Rabbi Dr. I. Epstein B.A., Ph.D., D. Lit.)
The Previous Lubavitcher Rebbe, in his memoirs, recounts a story about the Alter Rebbe's (Rabbi Schneur Zalman, the first Chabad Rebbe) great-grandfather, R' Baruch Batlan. Apparently, he was a tenant in a building which became inhabited by sheidim after the passing of the building's owners. After trying several ways to remove them, his Rebbe, R' Yoel, the Baal Shem of Zamoshtch, came and called them to a "Din Torah". The story is fascinating in its entirety, but in short, the Beis Din paskened that they must leave the building, so they did.
Interestingly, it appears that they are held by the ban to avoid inhabited places, and only violated it in this case on the orders of Ashmedai. The sheidim held that they were the legal heirs to the building's owners, because the owners' curses had created them.
This story took place in the mid-1600's
It is true that the Talmud Bavli clearly mentions shedim in many places. As in other areas, they followed the science of the time, so something that seems unscientific now was a reasonable belief back then.
However, that doesn't mean they were completely wrong. They felt there were certain harmful invisible forces that existed in the world and that one must protect himself from. Although we wouldn't call these forces 'demons' nowadays, we do know of other microscopic forces that can cause harm. So if they said one should wash his hands to get rid of "ruach rah" or "bad spirits", it wasn't exactly wrong. Washing hands does help get rid of the "bad spirits" of bacteria. While its true not all cases can be explained like this, the overall belief in 'demons' can often be connected to many real phenomena.
The Rambam, practically alone among the major commentators, has the almost unique view that sheidim do not exist, and the entire idea was a simple superstition, played upon by the Sages for use parables and other concepts. Consequently, he interpreted all the Gemaros and Midrashim that mention sheidim as allegories or the like. Though some of his interpretations can be found in Moreh Nevuchim, we unfortunately do not have his explanations to all the Aggados in Shas, though he did at one time plan on compiling such a book (see his introduction to the Moreh). His son Rav Avraham seems to hold his father's views on the matter. See, for example, his introduction to Aggados, printed in most editions of Ein Yaakov. The Meiri, in his running commentary of the Gemara, makes a point of trying to explain how the Rambam may have learned these Gemaras. The vast majority of Rishonim and Acharonim, however, chief among them the Ramban, are of the opinion that sheidim do in fact exist. This is primarily based on the hundreds of references in Chazal to sheidim, which certainly seem to exist. The Ramchal in Derech Hashem explains that sheidim are somewhat physical and somewhat spiritual beings. The Tannaim and Amoraim seemed to frequently meet and even interact with sheidim. The question remains: Why do we not see or detect sheidim nowadays? The simple answer is that we are not on the spiritual level to notice such beings. My Grandfather shlita told me that Rabbi Ruderman zt"l, late Rosh Yeshivah of Ner Yisroal, suggested a different reason. The Gemara in Pesachim 112b relates that certain great Sages were on the spiritual stature to decree, as it were, that the sheidim not reveal themselves on certain days of the week. Rav Ruderman suggested, perhaps somewhat in jest, that the very fact that the Rambam thought shaidim do not exist caused, as it were, their disappearance.
The Meiri reinterprets "mazikin" and the like wherever they appear in Shas as anthing from the evil inclination to thoughts of heresy. See here which lists instances of such reinterpretation by the Meiri.
Ralbag writes that sheidim are imaginary. He goes a step further than most other authorities who deny the existence of sheidim and actually attempts to prove that the Sages themselves (despite all their discussions about sheidim) believed that sheidim are imaginary.
The Talmud records the following about sheidim:
ואמר רב זוטרא בר טוביה אמר רב אבוקה כשנים וירח כשלשה איבעיא להו אבוקה כשנים בהדי דידיה או דילמא אבוקה כשנים לבר מדידיה ת"ש וירח כשלשה אי אמרת בשלמא בהדי דידיה שפיר אלא אי אמרת לבר מדידיה ארבעה למה לי והאמר מר לאחד נראה ומזיק לשנים נראה ואינו מזיק לשלשה אינו נראה כל עיקר אלא לאו שמע מינה אבוקה כשנים בהדי דידיה שמע מינה
R. Zutra b. Tobiah further said in the name of Rab: A torch is as good as two [persons] and moonlight as good as three. The question was asked: Is the torch as good as two counting the carrier, or as good as two besides the carrier? — Come and hear: ‘Moonlight is as good as three’. If now you say, ‘including the carrier there is no difficulty. But if you say, ‘besides the carrier’, why do I want four, seeing that a Master has said: To one [person] an evil spirit may show itself and harm him; to two it may show itself, but without harming them; to three it will not even show itself? We must therefore say that a torch is equivalent to two including the carrier; and this may be taken as proved. (Soncino translation)
Ralbag argues that if sheidim actualy existed then this description would not be true:
Commentary to Deuteronomy 32:17
והנה הכונה בשניהם הדמות הדמוים הכוזבים כי ענין מציאות השד הוא דמיון לבד ולזה אמרו רז"ל לאחד נראה ומזיק לשנים נראה ואינו מזיק לשלשה אינו נראה ואינו מזיק ואלו היה ענין שהיה לו מציאות בעצמו היה נראה לשלשה כמו שהוא נראה לאחד או לשנים
And the intent of both of them is the imagining of false imaginations. For the existence of the sheid is merely an imagination. That is why the Sages say, "to one it appears and harms, to two it appears but does not harm, and to three it does not appear nor harm". Now if the fact was that it has its own existence, it would appear to three just like it appears to one or two.
Demons as they appear in the Bavli seem to be a Babylonian belief because:
- The Yerushalmi hardly mentions them
- The Babylonians were quite concerned with protecting themselves from demons as we see from their incantation bowls
- The name Lilith (one of the demons) is thought to derive from lilitu, an Akkadian word meaning "spirits"
There are a few occurrences of terms in the Tanach referring to demons. The only instance in the Torah of the word shed is in Devarim 32:17:
יִזְבְּח֗וּ לַשֵּׁדִים֙ לֹ֣א אֱלֹ֔הַ אֱלֹהִ֖ים לֹ֣א יְדָע֑וּם חֲדָשִׁים֙ מִקָּרֹ֣ב בָּ֔אוּ לֹ֥א שְׂעָר֖וּם אֲבֹתֵיכֶֽם׃
That verse plainly states that demons have no power. Is that because they don't exist?