After being shown the ridiculousness of his beliefs, the Mujasim often resorts to arguing that reason (‘Aql) has no place in religion, and that rationalizing theology is contrary to what revelation (Naql) teaches. Obviously an excuse to justify belief in irrationalities. After all, nonsense is the only alternative to reason. So if you believed in nonsense, and you knew that what you believed in is nonsense, then that is exactly what you would say.
A Self Defeating Claim
The first problem that follows from asserting “reason is unreliable”, is that this is a self-defeating claim. How else can the Mujasim possibly prove that this claim is true, except by resorting to rational argumentation?
Furthermore, reason is the criterion for distinguishing the truth of Islam from the falsehood of disbelief. So the Muslim who claims that reason is unreliable, is undermining the basis upon which his faith is built upon in the first place.
To the above, the Mujasim might retort: “we accept the reliability of reason, but only in so far as it helps us prove our theology. However, when rational judgement conflicts with our theology, then our theology takes precedence.”
We respond: this is the epitome of irrationality. If you’re going to pick and choose which rational propositions to accept or reject based on your theology, then you cannot use reason to establish the truth of this theology. This is because you would be assuming the truth of the thing you’re trying to prove, before actually proving it.
Moreover, claiming that your theology takes precedence despite its being nonsensical, is the same as claiming that reason is unreliable. So why are you rationalizing your beliefs at all?
Revelation does not Teach us to Believe in Nonsense
Contrary to the claims of the Mujasim, revelation does not teach Muslims to refrain from rational judgment. This is highlighted throughout the Quran, which describes the believers as those who reason and reflect:
إِنَّ فِي خَلْقِ السَّمَاوَاتِ وَالْأَرْضِ وَاخْتِلَافِ اللَّيْلِ وَالنَّهَارِ لَآيَاتٍ لِّأُولِي الْأَلْبَابِ الَّذِينَ يَذْكُرُونَ اللَّهَ قِيَامًا وَقُعُودًا وَعَلَىٰ جُنُوبِهِمْ وَيَتَفَكَّرُونَ فِي خَلْقِ السَّمَاوَاتِ وَالْأَرْضِ رَبَّنَا مَا خَلَقْتَ هَٰذَا بَاطِلًا سُبْحَانَكَ فَقِنَا عَذَابَ النَّارِ
Surely in the creation of the heavens and the earth, and in the changes between night and day, are signs for those with intellect. Those who remember Allah while standing, sitting, or lying on their sides, thinking over the creation of the heavens and earth and saying: “Our Lord you did not create this without purpose, exalted you are, so protect us from the torment of the Fire.”
Which equates disbelief with irrationality, and considers those who do not use the reason that Allah ﷻ has gifted them with to be the worst of all creation:
إِنَّ شَرَّ الدَّوَابِّ عِندَ اللَّهِ الصُّمُّ الْبُكْمُ الَّذِينَ لَا يَعْقِلُونَ
Indeed, the worst of all creatures for Allah, are the deaf and dumb who do not reason.
Which promises those people punishment:
وَمَا كَانَ لِنَفْسٍ أَن تُؤْمِنَ إِلَّا بِإِذْنِ اللَّهِ ۚ وَيَجْعَلُ الرِّجْسَ عَلَى الَّذِينَ لَا يَعْقِلُونَ
It is not for any person to believe except by the permission of Allah, and He will place punishment upon those who do not reason.
And which criticizes those who, instead of think for themselves, opt to blindly follow in the footsteps of their predecessors:
وَإِذَا قِيلَ لَهُمْ تَعَالَوْا إِلَىٰ مَا أَنزَلَ اللَّهُ وَإِلَى الرَّسُولِ قَالُوا حَسْبُنَا مَا وَجَدْنَا عَلَيْهِ آبَاءَنَا ۚ أَوَلَوْ كَانَ آبَاؤُهُمْ لَا يَعْلَمُونَ شَيْئًا وَلَا يَهْتَدُونَ
And when they are told: “come to what Allah has revealed and to the Messenger.” They say: “sufficient for us are the beliefs of our forefathers.” They say this even when their forefathers knew nothing, and were not guided.
Amongst the hundreds of other passages encouraging the reader to think, reason, and reflect.
The Relationship Between Reason and Revelation
It should now be clear that the position of the Mujasim is based upon a false premise. That being: “it is possible for the ‘Aql to conflict with the Naql, so we must prefer one over the other”. In reality, we know the Naql is true because of the ‘Aql. In fact, the Naql itself commands the utilization of the ‘Aql. So there can be no contradiction between the two.
Given the above, revealed texts are classified into unequivocal (Qat’i Al-Dalala) and ambiguous (Dhani Al-Dalala).
Unequivocal: a text which the Arabic language does not allow for a multiplicity of interpretations for. For example:
لَيْسَ كَمِثْلِهِ شَيْءٌ
Nothing is like God’s resemblance.
Which is a text that can only be referring to God’s absolute uniqueness, and dissimilarity to everything else. The Arabic does not allow for any other interpretation.
Ambiguous: a text which the Arabic language allows for a multiplicity of interpretations for. For example:
الرَّحْمَٰنُ عَلَى الْعَرْشِ اسْتَوَى
The Most Merciful on Al-‘Arsh Istawa.
Which is a text whose Arabic, devoid of all context, allows for a wide range of possible interpretations. Amongst them:
1. God (the Most merciful) affects (Istawa) the Throne (Al-‘Arsh).
2. God (the Most merciful) subjugates (Istawa) creation (Al-‘Arsh).
3. God (the Most Merciful) sits (Istawa) on the Throne (Al-‘Arsh).
Unequivocal texts do not conflict with what is established by rational necessity. In fact, it is for this very reason that we affirm Islam to begin with.
As for the ambiguous texts, and given the fact that revelation cannot conflict with rational judgment, then reason is a perfectly fine standard for interpretation. Such that if we are faced with a text which affords a multiplicity of interpretations, and some of those interpretations conflict with rational necessity, then those conflicting interpretations are rejected for a possible alternative.
For example: “the Most Merciful on Al-‘Arsh Istawa”. We notice that the third interpretation from the list above (“God sits on the Throne”) conflicts with rational necessity. Since “sitting” is for bodies, while God is necessarily incorporeal. This third interpretation is therefore rejected, and one of the others must be affirmed instead of it.
 If the Mujasim considered reason to be a reliable standard for judgement, then the irrationality of his beliefs should have driven him to reject those beliefs as falsehood instead.
 Quran 3:190-1
 Quran 8:22
 Quran 10:100
 Quran 5:104
 Quran 42:11
 Quran 20:5