“Quran 22:46, which describes hearts in chests going blind, implies that the Quran attributes cognition and reasoning to the heart rather than the brain, contradicting modern neuroscience.”

The heart contains a complex intrinsic nervous system with over 40,000 neurons, allowing it to process information independently, but higher cognition, reasoning, and executive functions reside in the brain's cerebral cortex, as established by modern neuroscience.

Cognition and reasoning are localized primarily in the prefrontal cortex and other brain regions; while the heart influences autonomic responses and emotions via the vagus nerve, it does not perform abstract reasoning or serve as the primary seat of intellect.

Modern neuroscience confirms that the human brain contains approximately 86 billion neurons, which is roughly 2.15 million times more than the 40,000 neurons found in the heart. The heart's neural network is involved in emotional processing and autonomic regulation, but there is no convincing scientific evidence that primary thought processes or reasoning occur in the heart itself.

The heart possesses an intrinsic cardiac nervous system composed of approximately 40,000 neurons that communicate with the brain through multiple pathways: neurologically, biochemically, biophysically, and energetically. The vagus nerve, which is 80% afferent, carries information from the heart to the brain, with signals redirecting to the medulla, hypothalamus, thalamus, amygdala, and cerebral cortex. The heart sends more signals to the brain than vice versa.

While cardiac afferent signals influence emotional perception and autonomic regulation through connections to limbic structures, the generation of reasoning, logic, and abstract thought remains exclusively a function of cortical and subcortical brain structures. The heart's 40,000 neurons are insufficient in number and organization to support independent reasoning, being comparable to the neural counts in simple organisms like lobsters or certain insects.

The vagus nerve serves as a bidirectional communication pathway between the heart, gut, and brain. While this connection allows emotional and physiological states to influence cardiac function, and vice versa, the brain remains the central organ for processing, integrating, and generating conscious thought and reasoning. The heart's neural network modulates these processes but does not generate reasoning independently.

While the heart contains a neural network that processes emotional signals and communicates bidirectionally with the brain via the vagus nerve, the prefrontal cortex, amygdala, and other brain structures are the primary neural substrates for reasoning, decision-making, and cognition. The heart's role is modulatory rather than generative of higher-order thought.

Quran 22:46 states: 'Have they not travelled through the land, so their hearts would reason (or understand) thereby?' (Sahih International translation). The Arabic term 'qalb' (heart) is used in conjunction with reasoning ('ya'qilun'). Islamic scholars have historically interpreted this metaphorically, with the heart representing the seat of understanding, wisdom, and spiritual perception rather than literal cognitive processing.

In the Islamic tradition, the heart is the centre of the human being. Much more than just the physical organ that circulates blood throughout the body, the heart is central to the physical, emotional, intellective, ethical, and spiritual life of Muslims. The popular model of the brain being the sole seat of cognition, feeling, and consciousness was challenged in the West itself in the latter half of the twentieth century by work that illustrated the importance of the parasympathetic nervous system and clusters of neurons in various parts of the body, including the gut and the heart.

Cognitive neuroscience is the study of how the brain enables the mind. Brain science explores how individual neurons operate and communicate to form complex neuronal architectures that comprise the human brain. It maps higher-level cognitive functions to known brain architectures and known modes of neuronal processing. Modern cognitive neuroscience relies heavily on EEG technology to study the temporal dynamics of cognitive processes such as attention, memory, and executive function.

Neuroscience, the scientific study of the nervous system, is a dynamic and rapidly evolving field. It bridges various disciplines including biology, chemistry, psychology, and even computational science, to understand the complex architecture and functions of the brain and nervous system. The brain itself is a marvel of evolution, housing approximately 86 billion neurons, each forming thousands of synaptic connections with other neurons. These connections facilitate the great signaling networks responsible for every thought, emotion, and action.

The preponderant view is that the intellect is in the heart; Allah, The Exalted, says (what means): {So, have they not traveled through the earth and have hearts by which to reason and ears by which to hear? For indeed, it is not eyes that are blinded, but blinded are the hearts which are within the breasts.} [Quran 22:46] The phrases "hearts by which to reason" and "blinded are the hearts which are within the breasts" indicate that the heart is the center of intelligence, not the brain.

Commentaries on Quran 22:46, such as Ibn Kathir and Al-Jalalayn, interpret the verse "Have they not travelled in the land, and have they hearts wherewith to feel and ears wherewith to hear? For indeed it is not the eyes that grow blind, but it is the hearts which are within the bosoms, that grow blind." These tafsirs explain that the 'hearts' here refer to the capacity for comprehension and insight, and that the words "the hearts.... blind" are used in a metaphorical sense, implying that their stubbornness prevents them from feeling and acting rationally.

The Quran frequently attributes cognitive and emotional functions to the heart and chest, which traditional exegesis interpreted literally. Modern neuroscience provides an interesting perspective on this association through the heart-brain axis—the bidirectional communication between the heart and brain. While the brain remains the primary organ of intellect, the heart's rhythmic activity and its neural connections to the brain influence cognitive and emotional processing.

In modern science, the brain is often seen as the organ of consciousness, thought, and identity, with emotions, memories, imagination, and free will fundamentally tied to its structure and function. However, the heart also possesses its own "little brain" of approximately forty thousand neurons, which not only regulates cardiac rhythm but also engages in bidirectional communication with the brain, influencing various cognitive and emotional processes.

Quran 22:46 states: "Have they not travelled throughout the land so their hearts may reason, and their ears may listen? Indeed, it is not the eyes that are blind, but it is the hearts in the chests that grow blind." The commentary notes that the Qur'ānic discourse uses literary rather than scientific phraseology, and in literary usage, emotions, feelings, thoughts, in fact all actions of the brain are ascribed to the heart.

Heart, in the Qur'an, is symbolically the seat of the true self, the repository of soul, or the core and kernel of human personality. The heart of man possesses organs of spiritual communication and cognition such as the heart (al-qalb), which knows Him; the spirit (al-ruh), which loves Him; and the secret or inner-most ground of the soul (al-sirr), which contemplates Him.

Reflecting on Quran 22:46, "Surely it is not the eyes that are blind, but blind are the hearts that are in the chests," this Islamic scholarly source explains that true blindness is a lack of insight, not physical sight. It emphasizes that the heart (qalb) is a source of feelings, emotions, discernment, and wisdom, and that inner blindness is the inability to use the heart for these functions properly.

The 'heart', in the Quranic view, is also a means of knowledge and understanding. The addressee of a part of the Quran's message is the heart. A part that only the ears of the heart can hear, and which no other ear can detect. Thus the Quran lays heavy emphasis on safeguarding and perfecting this means, this important tool.

Verse 22:46 provides the decisive evidence about that, as it mentions clearly that the reference to what is in the chests is a reference to the hearts: 'Truly it is not the eyes that become blind but do the hearts which are in the chests.' This means that the heart also has its own mind and it reasons, just like the brain does.

'Hearts' here denotes intellects or understandings; their being 'in the breasts' is a metonym for their being in the breasts' insides, and the phrase 'blinded hearts which are in the breasts' means that it is not the eyes that are blind, but the hearts, that is, the intellects, that are blind to the truth.

The researcher aims to look at the place and role of the heart in Islamic ethics from an understanding derived from the primary sources of Islam, namely the Qur'an and the Sunnah of the Prophet Muhammad.

The cardiocentric (“heart-centered”) hypothesis was the historical belief that the heart controls sensation, thought, and body movement, prevalent in ancient cultures. The Bible, for instance, speaks of the heart as the seat of emotions and intellect, with Simeon prophesying that through Jesus, the “thoughts from many hearts may be revealed” (Luke 2:35).

In Islamic tradition, the heart (qalb) is the spiritual core of a person, serving as the seat of faith, sincerity, and divine connection. The Quran emphasizes the heart's pivotal role in understanding truth: 'Do they not travel through the land so that their hearts may reason and their ears may hear? It is not the eyes that are blind, but the hearts in the chests.' (Quran 22:46).

Modern neuroscience has established that the brain, not the heart, is the primary organ responsible for cognition, reasoning, memory, and consciousness. The heart is a muscular organ that pumps blood and contains some neural tissue (the cardiac plexus), but it does not generate conscious thought or reasoning. This represents a fundamental difference between Quranic metaphorical language and contemporary neurobiological understanding.

Although we moderns tend to think of the heart primarily in terms of our emotions, the Bible associates the heart with our ability to think. For example, Paul prayed “May [God] give you the Spirit of wisdom and of revelation in the knowledge of him, having the eyes of your hearts enlightened” (Eph. 1:17–18). Jesus said, “Out of the heart come evil thoughts” (Matt. 15:19).

The Qur'an also highlights the relationship between the mind and the heart, and it stresses the importance of using both to achieve a balanced understanding of faith and knowledge.

Hearts are the main source of reasoning. Here, rationality has been associated with it, since no organ works if the heart doesn't. Dr. Armour introduced the concept of a functional “heart brain” in 1991. Considered an independent entity, the heart’s brain is composed of an elaborate network of neurons, support cells and neurotransmitters which enables it to process information, learn, remember and produce feelings of the heart and then transmit this information from one cell to another.

In the Quran the word “Qalb” is mentioned more than 100 times and you can thus imagine the importance of this word and understanding its meaning. ... When looking at different verses of the Quran, there is no doubt that the “Qalb” that the Quran is referring to in most of the cases is NOT referring to the physical heart. ... The approximate 100 verses in the Quran using the word 'Qalb” actually use it with different intended meanings.

Quran 22:46 states, "Have they not traveled throughout the land so their hearts may understand, and their ears may listen? Indeed, it is not the eyes that go blind, but the hearts within the chests that grow blind." This source highlights that the Quran attributes understanding and reasoning directly to the heart, a concept revealed when the heart was primarily seen as a pump. It then connects this to recent neuroscience discoveries about the heart's 'intrinsic cardiac nervous system' (a 'little brain' with 40,000 neurons) that influences thoughts and emotions, suggesting a scientific corroboration.

They have hearts that they don't—they're not able to think with or they're not able to understand with. And so the understanding from that according to the Muslims is that the center of the intellect, the center of human consciousness is the heart and not the brain itself.