Sorcery and Divination are real

 Ramban (Devarim 18:9) THOU SHALT NOT LEARN TO DO AFTER THE ABOMINATIONS OF THOSE NATIONS. This also is an explanatory commandment, for He has already stated, and after the doings of the land of Canaan, whither I bring you, shall ye not do; neither shall ye walk in their statutes, and now he mentions their deeds and declares them to be abominations before G-d. He mentioned anyone that maketh his son or his daughter to pass through the fire, which, by way of the simple meaning of Scripture is a type of witchcraft, or, in the opinion of our Rabbis, it is the Molech. This is the truth as I have explained it in its place. 

Ramban (Devarim 18:9) THOU SHALT NOT LEARN TO DO AFTER THE ABOMINATIONS OF THOSE NATIONS.  He mentioned specifically meonein who is a diviner interpreting by the formations of the clouds, and the m’nacheish who divines by looking at the wings of the birds in flight or by listening to their chirping, something similar to what is written, for a bird of the air shall carry the voice, and that which hath wings shall tell the matter. 

Ramban (Devarim 18:9) He mentioned specifically a diviner interpreting by the formations of the clouds, and one  who divines by looking at the wings of the birds in flight or by listening to their chirping,

Ramban (Devarim 18:9) He mentioned a sorcerer, an inclusive term for all sorcery. Or a charmer, or one that consulteth a ghost or a familiar spirit — these are specific forms of sorcery. He also prohibited them to consult the sorcerer or the necromancer who uses the ghost, or, in any manner to seek information from them. He mentioned one that useth divination which involves divining future events, from the word ‘an oracle is in the lips of the king; his mouth trespasseth not in judgment, just as Scripture states, Balaam also the son of Beor ‘the soothsayer, and he was an enchanter, as it is said concerning him, he went not, as at the other times, to meet with enchantments, and it is further written, ‘divine unto me, I pray thee, by a ghost. He mentioned specifically a diviner interpreting by the formations of the clouds, and one  who divines by looking at the wings of the birds in flight or by listening to their chirping,

Ramban (Devarim 18:9) The word menachesh is derived from the expression ‘I made haste and delayed not, because whatever expedites knowledge of the future before it transpires is termed nachesh, that is to say, “we will hurry” and know sooner. Scripture states, For ‘all’ that do these things are an abomination unto the Eternal, but it does not say “for those that do ‘all’ these things …” because Scripture in calling the practitioner an abomination refers to most but not all of these practices. For the who divines by observing the clouds and he who prophesies by means of the wings or chirping of birds are not abominable, and G-d did not dispossess the Canaanites on their account, because all human beings desire to know things that are to come upon them, and engage in what they consider to be pursuits of wisdom.

Ramban (Devarim 18:9) And now, know and understand concerning the subject of sorcery, that when the Creator created everything from nothing, He made the higher powers to be guides for those below them. Thus He placed the earth and all things that are thereon in the power of the stars and constellations, depending on their rotation and position as proven by the study of astrology. Over the stars and constellations He further appointed guides, angels, and “lords” which are the soul of the stars and constellations. Now, their behavior from the time they come into existence for eternal duration, is according to the pattern the Most High decreed for them. However, it was one of His mighty wonders that within the power of these higher forces, He put configurations  and capacities to alter the behavior of those under them. Thus if the direction of the stars towards the earth be good or bad to a certain country, people, or individual, the higher dominions can reverse it of their own volition. 

Ramban (Devarim 18:9) Therefore, the author of the Book of the Moon, the expert in the field of necromancy, said, “when the moon, termed ‘the sphere of the world,’ is, for example, at the head of Aries (the Ram) and the constellation thus appears in a certain form, you should make a drawing of that grouping, engraving on it the particular time when this relative position appears and the name of the angel — one of the names mentioned in that book — appointed over it. Then perform a certain burning of incense in a certain specified manner, and the result of the influence of the relative position of the stars will be for evil, to root out and to pull down, and to destroy and to overthrow. And when the moon will be in a position relative to some other constellation you should make the drawing and the burning in a certain other manner and the result will be for good, to build and to plant.” Now this, too, is the influence of the moon as determined by the power of its heavenly guide. But the basic manner of its movement is by the wish of the Creator, Who endowed it so in time past, while this particular action is contrary thereto. This then is the secret of all forms of sorcery and their power concerning which the Rabbis have said that “they contradict the power of Divine agencies,” meaning that they are contrary to the simple powers with which the agencies have been endowed and thus diminish them in a certain aspect thereof. Therefore, it is proper that the Torah prohibit these activities in order to let the world rest in its customary way, in the simple nature which is the desire of its Creator. This is also one of the reasons for the prohibition of mixing seeds, for the plants resulting from such grafting are strange, giving rise to changes in the ordered course of the world for bad or good, aside from the fact that they themselves constitute a change in Creation, as I have already explained. Now, many scholars dispose themselves to be liberal with regard to these enchantments by saying that there is no truth in them whatsoever, for who tells the raven or the crane what will happen? But we cannot deny matters publicly demonstrated before the eyes of witnesses. Our Rabbis also, acknowledged their existence, as they have said in Eileh Shemos Rabbah: “For a bird of the air shall carry the voice — this refers to the raven and the craft of tiarin.” Birds in Arabic are called tiar and those versed in the divination of birds are called tiarin. This subject is also mentioned in the Gemara.But there is a secret to this matter. We have already made known that the constellations have lords that lead them, these being “the souls” of the circuits of the spheres, and the lords of the tail and head of Aries (the Ram) are near the earth, these being termed “the princes of the quiver,” that make the future known. It is through them that the signs in the birds indicate things to come, not for long duration or distant future do they tell, but only of events that are about to happen. Some make them known by utterance of bitter sounds resembling wailing over the dead, and some by spreading their wings. This is what has been said, for a bird of the air shall carry the voice a reference to those who suggest by their wings. Now all this is not considered abominable for the nations, instead it is considered wisdom for them. Thus the Rabbis have said: “And Solomon’s wisdom excelled the wisdom of all the children of the east. What was the wisdom of the children of the east? They were wise and crafty in divination of birds.” …And Solomon learned all this as part of his wisdom. Now, the knowledge referred to by the Midrash is understanding the chirping of birds, and “the craftiness” to explain a matter through spreading wings.Now, when Scripture included the diviner by clouds and the [other] diviners with the abominations mentioned, it reverted and explained, these nations, that thou art to dispossess, hearken unto diviners by clouds, and unto other diviners for their wisdom is to know future events, but as for thee, the Eternal thy G-d hath not suffered thee so to do. Scripture is thus stating, “G-d has prohibited you these specified practices such as passing a child through the fire because they are abominations before Him and because of them He drove these nations out from before you. He further forbade the enchanters and the diviners to you, because He gave you great eminence in setting you on high above all the nations of the earth, in that He will raise up a prophet in the midst of you and place His words in his mouth and you will hear from him what G-d will do. To know the future it will be unnecessary for you to resort to a diviner or soothsayer who receives the knowledge from the stars or from the lower powers among the lords of above, whose words are not all true and who do not provide all necessary information. But prophecy informs us of G-d’s desire and not one of its words will fall to the earth.” It is this which Scripture explains that if ever an ostensible prophecy does not come to pass, that is the thing which the Eternal hath not spoken. Thus you are His portion and His treasure, hearing His counsel from His mouth, while theirs is the portion of the constellations which they follow, this being the sense of the verse, but as for thee, the Eternal thy G-d hath not suffered thee so to do. This is the meaning of, which the Eternal thy G-d hath allotted unto all the peoples, as I have explained. And in the Sifre the Rabbis have said: “They hearken unto diviners by the clouds and other diviners. Perhaps you will say, ‘They have a source from which to inquire about the future and I have nothing from which to inquire.’ Scripture therefore states, but as for thee, the Eternal thy G-d hath not suffered thee so to do.” This is proof to all what we have explained that with respect to the diviners some root of the matter is found in them, and therefore Israel had a legitimate complaint in being enjoined from making use of. the diviners.