With the emergence of every era new needs and questions are generated which cause scientists and scholars to think and contemplate and strive to find appropriate answers to, and Sheikh Toosi is one the great scholars who has carried such a burden. The fundamentals of his political thought can be summarized in the following principles:
1- He believed that politics and religion aren’t separate.
2- His rational argument that proves the necessity of government and a political system and the presence of a leader is one of his notable theories.
3- Applying the rule of "Lotf" (Grace): He believes that Allah must designate a capable leader in the form of a prophet, Imam or a representative for the Imam that carries out political guardianship as one of his responsibilities.
4- The Political guardianship of the Foqaha in the society and people paying attention to this guardianship and the link between this guardianship and that of an Imam and the authorities of the Muslim leader are issues that have been discussed in Sheikh Toosi's books.
Moreover, achieving the principal chair of theology at the capital of the government from the Abbasi caliph can be great proof that he did not believe that religion and politics are separate, but rather he believed that politics are considered a part of religion.
Before answering the abovementioned question we must briefly mention the characteristics and biography of Sheikh Toosi:
Sheikh al-Ta’ifah Abu Ja'far Muhammad Bin Ali Toosi known as "Sheikh Toosi" was born in Ramadhan of the year 385 A. H. He completed his preliminary Islamic studies during his teenage years. At that time Toos, Neishaboor, Sabzevar, Rey and Qom were cities of knowledge, especially Qom, in which many scholars resided and was considered the center of Shias. It was during these years that, Soltan Mahmood Qaznavi ruled in Qazne and Khurasan and strongly promoted Sunni Islam on one hand and on the other, the kings of the Shia Ale Booye dynasty were ruling in most of Iran, and the cities of Rey, Fars and Baqdad had turned into their headquarters.
Sheikh Toosi whose first mentor was Sheikh Mufid and later on learned Fiqh, usool and Kalam from Seyyed Murteza, assumed the position of Shia leadership after Seyyed Murteza's demise. His greatness in knowledge and Taqwa was heard of by the Abbasi caliph that lead to Al-Qa’emo Bi’amrillah along with the Ale Booye dynasty granting him the principle chair of theology at the capital of the government. During those days this position was of great prestige and was granted to the most learned scholar of the country. Sheikh Toosi clearly shows his level of knowledge and Ijtihad in the first section of his book, "Tahzib al-Ahkam Fi Sharh al-Moqni’ah" that he wrote at the age of 27 during Sheikh Mufid's lifetime. This book is one of the four authoritative books of Shia and is referred to as an authentic hadith record.
Great scholars like Allameh Hilli have spoken in regard to Shaykh Tusi's great level of knowledge that can not be mentioned in this brief article.
In order to explain the greatness of Sheikh Toosi's political, social and scientific thought even more, we must point out the political-religious circumstances of his time. The fifth century of the Islamic calendar was the period of Baqdad's political development as the Abbasi's capital and is also considered the era of intellectual growth. This city consisted of knowledgeable scholars from among the greatest hadith scholars and Islamic theologians. From among these many scholars, Sheikh Toosi, who had arrived at Baqdad in the year 408 A. H., was of special eminence.
During the Abbasi Caliphate and especially during the reign of Mutawakkil (232-247), the government was leaning towards extreme Salafi’ism, putting sever pressure on other schools of thought (Supporters of Intellect) especially the Mo'tazelah and Shia and other groups that reconciled between the laws of Shari'ah and the understandings of intellect.
Although the Ale Booye dynasty that had conquered Baghdad in the year 334 A. H. was Shia, they did not try to give Shias an advantage over Sunnis and therefore were able to bring order and security to cities. Consequently the Muslim society was able to make great progress in fields of knowledge and science. That era was considered one of the flourishing times for cultural-religious freedom and a golden time of cultural growth in general.
The Ale Booye dynasty paid much attention to Shia scholars, especially Sheikh Toosi and Sheikh Mofid that were of greater eminence, and as a result Shia scholars also gained the respect of the Abbasi dynasty.
The fundamental principles of Sheikh Toosi's political ideology
Every era poses new questions and needs that call on scholars and scientists to find appropriate answers to. Sheikh Toosi is one of the faqihs and theologians who lived in the fourth and fifth century. He viewed the issues of his time from a Shia perspective and has suggested answers to them.
His political thought discusses issues like government and its related issues, the relation between people and government and the practical ways of opposing a government of tyranny.
Here we will mention some of his principles regarding political and governmental issues:
1- The Necessity of government: Sheikh Toosi proves the necessity of government and political order and guardianship through an intellectual argument, and then refers to traditional evidence as extra support for his opinion. In his book, Al Iqtisad al-Hadi, he says: "Except for the Shia Twelvers and the Mo'tazelahs of Baqdad and some late scholars, no one else believes in the necessity of government and imamate. But, in any event, this necessity can be proved in two ways:
First is to solely mention the intellectual necessity of political order in Islam and not even discuss the traditional evidences that prove or reject this opinion. The second method is to examine the narrative and religious evidences which prove the necessity of an imam and leader whose role in protecting the shari’ah and religion is proved through rational arguments."
After explaining these two methods, he then mentions that he prefers the first method and explains the rational arguments that prove the necessity of Imamate:
A: People are not infallible and may make mistakes and neglect a wajib act, therefore if there were a capable leader that enjoyed political legitimacy and was also supported by the people, his presence will result in protecting people from their enemies, punishing the wrongdoers, and taking back the right of the weak from the oppressors and consequently the society will move towards prosperity and salvation and will be kept away from chaos and disorder.
B: The rule of Lotf (Grace) asks for Allah to designate a politically capable leader for the Islamic society, therefore Shiekh Toosi believes in the necessity of Imamate and a political leadership that undertakes political supervision of the people. He argues that Allah does not do wrong acts due to his justice and wisdom and does not neglect any necessary action. Therefore, if Allah has granted people the shariah, it is logically necessary for him to also guarantee its practical execution and this is exactly what the rule of Lutf asks for.
2- Who is the Leader?
Due to the fact that Allah is the true governor of this world and that people are not immune from mistake and cannot choose the capable leader for themselves, applying the rule of Lotf he draws the conclusion that it is necessary for Allah to designate an individual as the political guardian and leader of the society. The first manifestation of this leadership was the governance of the prophet as Allah has mentioned in the Quran: "The Prophet is closer to the faithful than their own souls." Quranic commentators have explained this closeness to be the prophet's right to govern and preside over people and the people's obligation to obey him. After the prophet, this right was passed on to the Imams and consequently all must obey them.
3- The Governance of the Imam
Sheikh Toosi perceives an Imam's political governance as the manifestation of the Imam's general leadership by which he must supervise all spiritual and physical aspects of people's lives. On the other hand people must obey the Imam so that his decisions are carried out in society.
4- The Governance of the Imam's representative
In the two mentioned cases, meaning during the presence of the prophet or an Imam, Sheikh Toosi holds that the leader must be infallible and greater than all other individuals in all terms, but regarding a third case in which the Imam or the prophet is not present, he insists that the Imam's representative must assume this responsibility, because the Islamic society must be kept alive and the commands of Allah must be carried out.
"In regard to the political guardianship of an Imam, Sheikh Toosi mentions the features that all political leaders must possess. Moreover, factoring in the many authorities of the Foqaha in fields of Ifta' (issuing fatwas), Qaza (Judgment), executing Ahkam and resolving financial issues during the Imam's occultation, Sheikh Toosi believes that a well-qualified faqih has the same scope of authority as an Imam, except areas of authority that are a result of a certain characteristic that only imams possess. On this basis, although Sheikh Toosi has not mentioned the term "The general representation of Foqaha for the Imams" in his jurisprudential and theological works, but has mentioned all the features a general representative would have and has given the faqih governmental authorities.
Other issues like the scope of the authority of the Muslim leader, the goals of Islamic government, the mutual relations between people and governors, the role of people in an Islamic government and people and oppressive governors, etc. can also be analyzed from Shiekh Toosi's political thought, but due to the briefness of this article we will explain them in a different article.
 Ali Davani, Hezareye Sheikhe Tusi, vol. 1, pp. 3-4.
 Seyyed Mohmmad Reza Musaviyan, Andisheye Siyasiye Sheikhe Tusi, pp. 18-25 (abridged).
 Ibid, pp.g 27-31 (abridged).
 Sheikh Tusi, Al-Iqtisad al-Hadi, pg. 183.
 Ibid, pg. 189 (summary).
 Al-Rasa’il al-Ashr, pg. 112.
 Ibid, pg. 103.
 Andisheye Siyasiey Sheikhe Tusi, pg. 58.
 Refer to: Question 1725 (website: 1740), The political dimensions of Sheikh Tusi’s thought.