Another point is why this discipline has been called " 'ilm al-kalam", and when this name was given to it. Some have said that it was called "kalam" (lit. speech) because it gives an added power of speech and argument to one who is well-versed in it. Some say that the reason lies in the habit of the experts of this science who began their own statements in their books with the expression "al-kalamu fi kadha". Others explain that it was called "kalam" because it discussed issues regarding which the Ahl al-Hadith preferred to maintain complete silence. Yet according to others this name came to be in vogue when the issue whether the Holy Qur'an (called "kalamullahi") ,the Divine Utterance , i.e. the Holy Qur'an) is created (makhluq) or not, became a matter for hot debate amongst the Muslim - a controversy which led to animosity between the two opposite camps and bloodshed of many. This is also the reason why that period is remembered as a "time of severe hardship" - mihnah. That is, since most of the debates about the doctrines of the faith revolved around the huduth (createdness, temporality) or the qidam (pre-eternity) of the "Utterance" or kalam of God, this discipline which discussed the principal doctrines of the faith came to be called " 'ilm al-kalam" (lit. the science of the Utterance). These are the various opinions that have been expressed about the reason why 'ilm al-kalam was given this name.
The Various Schools of Kalam:
The Muslims differed with one another in matters of the Law (fiqh), following differing paths and dividing into various sects, such as Ja'fari, Zaydi, Hanafi, Shafi'i, Maliki and Hanbali, each of which has a fiqh of its own. Similarly, from the viewpoint of the doctrine, they divided into various schools, each with its own set of principal doctrines. The most important of these schools are: the Shi'ah, the Mu'tazilah, the 'Asha'irah, and the Murji'ah.
Here it is possible that the question may arise as to the reason behind such regretful division of the Muslims into sects in matters dealing with kalam and fiqh, and why they could not maintain their unity in these spheres. The difference in matters of kalam causes disunity in their Islamic outlook, and the disagreement in the matter of fiqh deprives them of the unity of action.
Both this question and the regret are justified. But it is necessary to pay attention to the two following points:
(i) The disagreement in issues of fiqh among the Muslims is not so great as to shatter the foundations of the unity of doctrinal outlook and mode of practice. There is so much common in their doctrinal and practical matters that the points of difference can hardly inflict any serious blow.
(ii) Theoretical differences and divergence of views is inevitable in societies in spite of their unity and agreement in principles, and as long as the roots of the differences lie in methods of inference, and not in vested interests, they are even beneficial; because they cause mobility, dynamism, discussion, curiosity, and progress. Only when the differences are accompanied by prejudices and emotional and illogical alignments, and lead individuals to slander, defame, and treat one another with contempt, instead of motivating them to endeavour towards reforming themselves, that they are a cause of misfortune.
In the Shi'ite faith, the people are obliged to imitate a living mujtahid, and the mujtahidun are obliged to independently ponder the issues and form their independent opinions and not to be content with what has been handed down by the ancestors. Ijtihad and independence of thought inherently lead to difference of views; but this divergence of opinions has given life and dynamism to the Shi'ite fiqh. Therefore, difference in itself cannot be condemned. What is condemnable is the difference which originates in evil intentions and selfish interests, or when it centres around issues which drive Muslims on separate paths, such as the issue of imamah and leadership, not the difference in secondary and non-basic matters.
To undertake an examination of the intellectual history of the Muslims so as to find which differences originated in evil intentions, vested interests, and prejudices, and which were a natural product of their intellectual life, whether all points of difference in the sphere of kalam should be regarded as fundamental, or whether all problems in fiqh should be regarded as secondary, or if it is possible that a difference in kalam may not be of fundamental significance whereas one in fiqh may have such importance - these are questions which lie outside the brief scope of this lecture.
Before we take up the schools of kalam for discussion, it is essential to point out that there has been a group of scholars in the Islamic world which was basically opposed to the very idea of 'ilm al-kalam and rational debate about Islamic doctrines, considering it a taboo and an innovation in the faith (bid'ah). They are known as "Ahl al-Hadith." Ahmad ibn Hanbal, one of the imams of jurisprudence of the Ahl al-Sunnah, stands foremost among them.
The Hanbalis are totally against kalam, Mu'tazilite or Ash'arite, not to speak of the Shi'ite kalam. In fact they are basically opposed to logic and philosophy. Ibn Taymiyyah, who was one of the eminent scholars of the Sunni world, gave a verdict declaring kalam and logic as 'unlawful'. Jalal al-Din al-Suyuti, another figure among the Ahl al-Hadith, has written a book called Sawn al-mantiq wa al-kalam 'an al-mantiq wa al-kalam ("Protecting speech and logic from [the evil of] 'ilm al-kalam and the science of logic").
Malik ibn Anas is another Sunni imam who considers any debate or inquiry about doctrinal matters to be unlawful. We have explained the Shi'ite viewpoint in this matter, in the introduction to Vol.V of Usul-e falsafeh wa rawish-e riyalism. 
The important schools of kalam, as mentioned earlier, are: Shi'ah, Mu'tazilah, Asha'irah, and Murji'ah. Some sects of the Khawarij and the Batinis, such as the Isma'ilis, have also been considered as schools of Islamic kalam. 
However, in my view, none of these two sects can be considered as belonging to the schools of Islamic kalam. The Khawarij, although they held specific beliefs in the matters of doctrine, and perhaps were the first to raise doctrinal problems by expressing certain beliefs about Imamah, the kufr (apostasy) of the fasiq (evil-doer, one who commits major sins), and considered the disbelievers in these beliefs as apostates, but they did not, firstly, create a rationalist school of thought in the Muslim world, and, secondly, their thinking was so much deviated - from the viewpoint of the Shi'ites - that it is difficult to count them among Muslims. What makes things easy is that the Khawarij ultimately became extinct and only one of their sects, called "Abadiyyah" has some followers today. The Abadiyyah were the most moderate of all the Khawarij, and that is the reason why they have survived until today.
The Batinis, too, have so much liberally interfered in Islamic ideas on the basis of esotericism that it is possible to say that they have twisted Islam out of its shape, and that is the reason why the Muslim world is not ready to consider them as one of the sects of Islam.
About thirty years ago when the Dar al-Taqrib Bayna al-Madhahib al-'Islamiyyah was established in Cairo, the Imamiyyah Shi'ah, the Zaydiyyah, the Hanafi, the Shafi'i, the Maliki and the Hanbali sects, each of them had a representative. The Isma'ilis tried hard to send a representative of their own; but it was not accepted by other Muslims. Contrary to the Khawarij, who did not create a system of thought, the Batinis, despite their serious deviations, do have a significant school of kalam and philosophy. There have emerged among them important thinkers who have left behind a considerable number of works. Lately, the Orientalists have been showering great attention on the Batini thought and works.
One of the prominent Isma'ili figures is Nasir Khusrow al-'Alawi (d. 841/1437-38), the well-known Persian poet and the author of such famous works as Jami' al-hikmatayn, Kitab wajh al-Din, and Khuwan al-'ikwan. Another is Abu Hatam al-Razi (d. 332/943-44), the author of A'lam al-nubuwwah. Others are: Abu Ya'qub al-Sijistani, the author of Kashf al-mahjub (its Persian translation has been recently published), who died during the second half of the 4th/l0th century; Hamid al-Din al-Kirmani, a pupil of Abu Ya'qub al-Sijistani, has written a large number of books about the Isma'ili faith; Abu Hanifah Nu'man ibn Thabit, well-known as Qadi Nu'man or "the Shi'ite Abu Hanifah" (i.e. Isma'ili); his knowledge of fiqh and hadith is good, and his well-known book Da'a'im al-'Islam has been printed by lithotype several years ago.
We shall begin our discussion - and we shall explain later why - with the Mu'tazilah. The emergence of this sect took place during the latter part of the first century or at the beginning of the second. Obviously 'ilm al-kalam, like any other field of study, developed gradually and slowly attained maturity.
First we shall enumerate the principal Mu'tazilite beliefs, or what is better to say, the basic and salient points of their school of thought. Second, we shall point out the well-known Mu'tazilite figures and speak of their fate in history. Then we shall give an account of the main outlines of the transitions and changes in their thought and beliefs.
The opinions held by the Mu'tazilah are many, and are not confined to the religious matters, or which according to them form an essential part of the faith. They cover a number of physical, social, anthropological and philosophical issues, which are not directly related with the faith. However, there is a certain relevance of these problems to religion, and, in the belief of the Mu'tazilah, any inquiry about the matters of religion is not possible without studying them.
There are five principal doctrines which, according to the Mu'tazilah themselves, constitute their basic tenets:
(i) Tawhid, i.e. absence of plurality and attributes.
(ii) Justice ('adl), i.e. God is just and that He does not oppress His creatures.
(iii) Divine retribution (at-wa'd wa al-wa'id), i.e. God has determined a reward for the obedient and a punishment for the disobedient, and there can be no uncertainty about it. Therefore, Divine pardon is only possible if the sinner repents, for forgiveness without repentance (tawbah) is not possible.
(iv) Manzilah bayna al-manzilatayn (a position between the two positions). This means that a fasiq (i.e. one who commits one of the "greater sins," such as a wine imbiber, adulterer, or a liar etc.) is neither a believer (mu'min) nor an infidel (kafir); fisq is an intermediary state between belief and infidelity.
(v) al-'amr bil ma'ruf wa al-nahy 'an al-munkar [bidding to do what is right and lawful, and forbidding what is wrong and unlawful]. The opinion of the Mu'tazilah about this Islamic duty is, firstly, that the Shari'ah is not the exclusive means of identifying the ma'ruf and the munkar; human reason can, at least partially, independently identify the various kinds of ma'ruf and munkar. Secondly, the implementation of this duty does not necessitate the presence of the Imam, and is a universal obligation of all Muslims, whether the Imam or leader is present or not. Only some categories of it are the obligation of the Imam or ruler of Muslims, such as, implementation of the punishments (hudud) prescribed by the Shari'ah, guarding of the frontiers of Islamic countries, and other such matters relating to the Islamic government.
Occasionally, the Mu'tazilite mutakallmun have devoted independent volumes to discussion of their five doctrines, such as the famous al-'Usul al-khamsah of al-Qadi 'Abd al-Jabbar al-'Astarabadi (d. 415/ 1025), a Mu'tazilite contemporary of al-Sayyid al-Murtada 'Alam al-Huda and al-Sahib ibn 'Abbad (d. 385/995).
As can be noticed, only the principles of tawhid and Justice can be considered as parts of the essential doctrine. The other three principles are only significant because they characterize the Mu'tazilah. Even Divine Justice - although its notion is definitely supported by the Qur'an, and belief in it is a necessary part of the Islamic faith and doctrine - has been made one of the five major doctrines because it characterizes the Mu'tazilah. Or otherwise belief in Divine Knowledge and Power is as much an essential part of the Islamic faith and principal doctrine.
Also in the Shi'ite faith the principle of Divine Justice is considered one of the five essential doctrines. It is natural that the question should arise: what is particular about Divine Justice that it should be counted.among the essential doctrines, though justice is only one of the Divine Attributes? Is not God Just in the same manner as He is the Omniscient, the Mighty, the Living, the Perceiver, the Hearer and the Seer? All those Divine Attributes are essential to the faith. Then why justice is given so much prominence among the Divine Attributes?
The answer is that Justice has no advantage over other Attributes. The Shi'ite mutakallimun have specially mentioned justice among the principal Shi'ite doctrines because the Ash'arites - who form the majority of the Ahl al-Sunnah - implicitly deny that it is an Attribute, whereas they do not reject the Attributes of Knowledge, Life, Will, etc. Accordingly, justice is counted among the specific doctrines of the Shi'ah, as also of the Mu'tazilah. The above-mentioned five doctrines constitute the basic position of the Mu'tazilah from the viewpoint of kalam, otherwise, as said before, the Mu'tazilite beliefs are not confined to these five and cover a broad scope ranging from theology, physics and sociology to anthropology, in all of which they hold specific beliefs, a discussion of which lies outside the scope of these lectures.