Thus, the first question about knowledge is the issue about the possibility of knowledge—is it possible for man to know? Pyrrho said that knowledge or ma‘rifah is impossible (for reasons I enumerated earlier). Of course, others exposed the flaw in Pyrrho’s argument. On our part, we exposed this flaw elsewhere in the footnotes of Uṣūl-e Falsafeh wa Rawish-e Realism (The Principles of Philosophy and the Method of Realism). It is thus said to Pyrrho: “You say that senses make mistakes because sometimes your eyes squint; you see a person as if having two heads; you see a piece of wood as broken in a water container; and so on and so forth. You say that you observe that the senses make mistakes. When you observe that senses make mistakes, do you know that senses indeed make mistakes, or do you still doubt that the senses make mistakes? When you say that when you wake up and rub your eyes, you can see double, with a person standing in front of you as if they are two, having four eyes (instead of two), you say that it is not so. Do you really know that it is not so, or you just guess that it is not so?” He says, “No, I know that it is not so; that person does not have two heads or two noses.” Then he would be told: “So, you realized this mistake with certainty by yourself; how can you say then that you have not obtained knowledge? This is itself [a kind of] knowledge. When you say that reason makes a mistake in a particular instance, you say with certainty that it makes a mistake. That is, you know that it makes a mistake; therefore, you have arrived at the truth. Unless a person has arrived at the truth, he cannot perceive that the opposite view is wrong.”
As such, it must [rather] be said: “The human being makes mistakes in some of his sense perceptions, but not others. So, we must classify the issue; we must look for a criterion. With a certain criterion, let us see if we could somehow correct the things in which we make a mistake, or not. Just because of the fact that we make a mistake in some cases, why should we deny the essence of knowledge?! Why [we should treat as identical] the cases in which we make a mistake and the cases we do not doubt that we make a mistake (such as the instance when we realize that we have made a mistake)?” The [above] argument of Pyrrho is like the following couplets of Sa‘dī:
چو از قومي يكي ﺑﻲدانشي كرد نه كه را منزلت ماند نه مِه را
ﻧﻤﻲبيني كه گاوي در علفزار بيالايد همه گاوان ده را
When one of a tribe has done a foolish thing
No honor is left either to the low or the high.
Can’t you see how one ox of the pasturage
Defiles all oxen of the village?
This is true for social issues. If certain members of a society belonging to a certain class—say, the clerics—behave untowardly and wickedly, the integrity of others would also be tarnished; otherwise, there is no point in hanging ‘Amr for the sin of Zayd:
گنه كرد در بلخ آهنگري به شُوشتر زدند گردن مسگري
A blacksmith committed a crime in Balkh
Some of our sense perceptions make mistakes; some others are definitely correct. Let us look for the solution to erroneous perceptions. Out of this, the science of logic (manṭiq) came into being. Logic is a science which is [the foundation of] the theory of knowledge. That is, in this very theory of the possibility of knowledge and impossibility of knowledge, it makes no difference for the one who said that it is impossible to know while the one who said that it is possible to know is looking for a criterion for distinguishing erroneous knowledge from correct knowledge and [assuming that] there must be such a criterion. Now, as to what extent logic could play a role or function is a question which, if we try to address, would prevent us from dealing with more important issues.
We must see what the Qur’an says in this regard. Does the Qur’an support the view that knowledge is possible? Or, does the Qur’an also say that it is impossible to know? Now, if knowledge is possible (as there is the Qur’an and the religion), then the very knowledge in ideology must have a ruling, and that ruling would answer: Is knowledge lawful or not? Is knowledge permissible or not? There are two questions here. [One is whether knowledge is possible or not, and the other is whether knowledge is permissible or not.] As you are well aware of, the issue is presented in the Torah in a specific way and since according to us, the Torah is one of the books that experienced distortion (taḥrīf)—that is, in assessing a case mentioned in both the Qur’an and the Torah by the criterion of the Qur’an—when we see that the account of the Torah contradicts that of the Qur’an, for us there is no doubt that the account of the Torah has been distorted. In the Qur’an—a religious scripture—the issue is never raised in a philosophical manner—whether knowledge is possible or not. Rather, we must see and analyze whether the Qur’anic inferences of these issues are based upon the possibility of knowledge or its impossibility. Are the Qur’anic injunctions justifiable on the basis of the possibility of knowledge or its impossibility? And the other question is: is knowledge permissible or not?
 Knowing (shinākhtan) is equivalent to certainty (yaqīn) as doubting (shakk) is the opposite of knowing. “Knowing” means for me to reach a point to think it is such and not to doubt that what I think as such is correct; that I do not doubt its correctness, for if I doubt then there is no knowledge for me but only “Is…?” “Is it so?” “I do not know.” “Perhaps there is.” “Perhaps there is not.” There are many “I-do-not-know’s”. Knowing is “knowing” when there is no doubt. If there is doubt, then it is [the same] “I-do-not-know” [episode].
 It refers to ‘Allāmah Sayyid Muḥammad Ḥusayn al-Ṭabaṭabā’ī’s work in collaboration with his student Āyatullah Muṭahharī who provided footnotes and explanations easily comprehensible to the common people. The work was designed to present Islamic philosophy as a superior alternative to Marxism. [Trans.]
 Shaykh Muṣlīḥ al-Dīn Sa‘dī (1184-1283) was one of the greatest Persian poets. Born in Shīrāz, he studied Sufi mysticism at the Nizāmiyyah madrasah in Baghdad with Shaykh ‘Abd al-Qādir al-Jīlānī and with Shahāb al-Dīn Suhrawardī. He made the pilgrimage to Mecca many times and traveled to Central Asia, India, and the Seljuq territories in Anatolia, Syria, Egypt, Arabia, Yemen, Abyssinia, and Morocco. His best known works are the Būstān (Garden) and the Gulistān (Rose-Garden), also known as Sa‘dī-Nāmeh. The former is a collection of poems on ethical subjects while the latter is a collection of moral stories in prose. He also wrote a number of odes and collections of poems known as Pleasantries, Jests and Obscenities. His influence on Persian, Turkish and Indian literature has been very considerable, and his works were translated into European languages from the 17th century onward. [Trans.]
 Gulistān, chapter 2 “The Morals of Dervishes,” story 5. Edward Rehatsek (trans.), Gulistan or Rose Garden of Sa‘di (Tehran: Peyk-e Farhang, 1998), p. 38. [Trans.]
 Known as Bactra to the Greeks and Baktri or Bagdhi to the Persians, Balkh was an ancient city and center of Zoroastrianism in Khurāsān in today’s Northern Afghanistan. [Trans.]
 Shūshtar: an ancient fortress city in the Khūzistān province in southwestern Iran and approximately 92 km away from Ahwāz, the center of the province. [Trans.]
 Among the Fārsī-speaking people, this couplet is known as Dīwān-e Balkh, literally “the Court of Balkh,” which alludes to any office or authority whose judgment is not based on logic and reason as well as what is right and just. [Trans.]
 This is because we want to have ample time to deal with this subject: on which criteria is the issue of knowledge based in this divine school—this divine worldview of ours upon which our ideology is based? This is our main concern. Other issues are preliminary or introductory in nature for us. That is, we shall touch upon them only to the extent necessary; otherwise, if we want to tackle logic, then we have syllogistic logic; we have symbolic logic; the Organon (manṭiq-e arasṭū) claims to be syllogistic logic. Has the Organon duly performed its alleged function or not? To address them requires many sessions, which are not necessary for our discussion, for these questions are presently not raised among materialists and non-materialists.
(Murtada Mutahhari, THE THEORY OF KNOWLEDGE: AN ISLAMIC PERSPECTIVE, trans. Mansoor Limba (Tehran: IHCS and ABU, 2011), pp. 9-11.