Avicenna's Argument

Avicenna detailed the argument for the existence of God in three books: Al-Shifa (The Book of Healing), Al-Nejat, and Al-Isharat wa al-Tanbihat.^[5] This seems to be the first application of the Seddiqin argument. According to Muhammad Legenhausen, few people gave much credence to Avicenna's proof.^[6] Avicenna described the argument as seddiqin (Borhane seddiqin) because this argumentation applies to those who are truthful. According to Avicenna, those who are truthful persons possess an argument which is pure truth and with no signs of untruthfulness. In other words, Seddiqin argues for the existence of God and truth by one argument: the essence of Truth and God. Avicenna refers to the argument as follows:

Consider how our statements in proving the First-Almighty and His unity and his acquittance from all deficiencies did not anything other than existence itself; and there is no need to consider his creatures and acts. Also they are, also, some reasons for His existence, but this kind of demonstration is a stronger one and a higher position. This means when we survey the mode of existence we consider that existence in so far as it is existence, witness to the existence of God, then it witness to other beings.

— Avicenna, Ayatollahi Hamidreza, The existence of God

Also Avicenna quotes the Quran to support the argumentation: "Is it not sufficient as regards your Lord that he is witness over all things" (Surah 41, verse 53).^[7]

Avicenna focuses on the view that God is a necessary being in himself.^[8] This argument is based on contingency. The claim of Avicenna is that we can establish the existence of God directly by consideration of his existence itself. In the proof of sincere men, Avicenna tries to reach the existence of God through an analysis of existence itself along with the supposition that God is the necessary existent. According to him, if we reflect on any things generally and consider only their existence, then the existence is either necessary or not. If the existence is necessary then it is God (called al-Wajib al-Wujud), and if the existent is not necessary then it is impossible or contingent. It is not impossible because we assume that it is something therefore it must be contingent. In fact, if we consider the existence of existent alone then it is either the necessary or contingent. The contingent, in respect to its existence, needed ab alio or something which brings it into existence. The preponderant itself is necessary or contingent. If it is necessary, then it is God. If it is contingent, then it is in need of a transcendent cause. The series of these transcendent causes themselves are finite or infinite. The finite series finally arrives at God, since the last member doesn't need any cause and is therefore, by itself, the Necessary Existent. If the series was infinite, then the series as a whole needed its components in its existence and therefore must be contingent.^[9]

Shihab al-Din Yahya Suhrawardi’s Argument

Suhrawardi, founder of illuminationism, also referred to the seddiqin. This version is important because he introduced mystical ideas into the argument. In addition, Mulla Sadra Shirazi was closer to Suhrawardi than was Avicenna.^[10] Suhrawardi had distinct terminology for the argument. For instance, he used "the lights of light" in place of God or necessary being. He used "rich" for necessary being and "poor" for contingent being. His argument in his collected works are as follows:

If immaterial light were poor in its essence, then its need would not be for a dusky dead substance, for it would not be proper that the more noble and complete should be founded on that which is not in that direction [toward nobility], and how could the dusky benefit the light? So, if the immaterial light is needy in its occurrence, then there should be for it a supporting light. Then the ordered supporting lights will not go on to an infinite regress, as you know from the proof for the necessity of an end for things ordered into collections. So, there must be an end to the supporting lights, and their accidents and barzakh [mediation] and shapes are [directed] to a light beyond which is no further light, and that is the Light of Lights, the Comprehensive Light, the Self-Subsistent Light, the Sacred Light, the most Magnificent and Lofty of Lights, and this is the Almighty Light, and this is the absolutely needless, for no other thing is beyond it

— Shihab al-Din Yahya Suhrawardi, " Majmu’ah musannifat shaykh ishraq " (1957-1960), Henty Corbin,the collected works of Sheykh Eshraq.1977, Vol. 2, p. 121

Of course, the above argument depends upon the impossibility of an infinite regress, but in other books he presents an argument in which there is no need for the supposition of infinite regress. This argument is as follows:

And also by another route: A thing does not require its own nonexistence, otherwise it would not occur. The Light of Lights is a unity; in itself it has no conditions. All else is subject to it. Since it has no condition and no opposite, there is nothing which can void it, so it is self-sufficient and everlasting. And the Light of Lights is not attached to any sort of shape, whether luminous or dark, and attributes are not possible for it in any aspect

— Shihab al-Din Yahya Suhrawardi, " Majmu’ah musannifat shaykh ishraq " (1957-1960), Henty Corbin,the collected works of Sheykh Eshraq.1977, Vol. 2, 122-123

This argument has a close link with the metaphor of light. According to Surawardi, if we suppose that existence is contingent then, if the regress of infinite is impossible, consequently there must be a first.^[11]

Mulla Sadra's Argument

Mulla Sadra explained the proof of the sincere in a way different from both Avicenna's version as well as Suhrevardi's. The differentiation with Avicenna differs in the argument of the existence as an existent. Mulla Sadra begins his argument with an existent in the world until he reaches the necessary existent. Mulla Sadra also rejects Suhrawardi’s statement of the argument from contingency.^[12]

And it is stated that existence, as was mentioned before, is a single, simple, objective reality (haqiqah ‘ayniyah). There is no difference in the essences (dhat) of its individuals, but only in perfection and imperfection and in intensity and weakness, or in other matters [not related to existence itself], for example, that between the whatnesses (mahiyyah) of the same species. The ultimate perfection for which there is nothing greater is that which does not depend on anything else, and nothing greater than it can be imagined, for all imperfect things are dependent on others, and are in need of the more complete. It has become clear that the complete is prior to the imperfect, and activity is prior to potentiality. Existence is prior to nothingness. It has also been made clear that the completion of a thing is that very thing with an addition. Therefore, existence is either independent of others or essentially (li dhat) in need of others.

The First is the Necessary Existent, which is Pure Existence than which nothing is more complete, and It is unmixed with non-existence and imperfection. The second is other than this, but is Its actions and effects, which rest upon nothing but It. And, as was mentioned, the reality (haqiqah) of existence has no deficiency, and if any imperfection occurs in it, it is only due to its being an effect, and this is because the effect cannot be of an equal degree to the existence of its cause. So, if existence were not something made (maj‘ul), dominated by that which brings it into existence and brings it about (as according to what it requires), it would not be imaginable that it should have any sort of imperfections. For the reality of existence, as you know, is simple. It is unlimited, not determinate, except for pure activity and occurrence, otherwise there would be mixture in it or it would have some essence other than existence in it.

We have also mentioned that if existence is an effect, then it is in itself something which is made by a making which is simple, and its essence (dhat) in itself is in need (muftaqra) of a maker (ja‘il), and it relies in its substance and essence (dhat) on its maker. Thus, it has been proven and made clear that existence is either complete reality (haqiqah) necessary in its ipseity (huwiyah), or it is essentially (dhatan) in need of it [i.e. that which is necessary in itself], substantially (jawhariyah) relying on it. According to each of these alternatives it has been proven and demonstrated that the existence of the Necessary Existent is in its ipseity needless of any other. This is what we intended. And know that this argument is extremely firm and strong, and its source is near to the way of the Illuminationists, which is based on the principle of light.

— Sadr al-Din Muhammad Shirazi, " al-Hikmat al-muta’allihiyah fi al-asfar al-’arbah " (Qom: Mustafavi, 1386/1966), Legenhausen, 2004, p. 10