To begin with, it is not a matter of wisdom nor is it a legal duty imposed in Islam that all Muslim students devote themselves to learn Shari`ah and abandon worldly studies. There are some branches of knowledge that Muslims must learn; they are even considered sinful by deserting them. These branches of knowledge cover all fields of our life. Examples are medicine, engineering, accounting, technology, management, military, economic, and political sciences, and craftwork. These are some of the disciplines that must be studied, and, further, there has to be a considerable number of specialists in such disciplines within the Muslim community. Since Islam has come with a universal message, Muslims should be acquainted with all worldly branches of knowledge. In short, it is not of sound judgment to forsake worldly sciences to study shari`i ones, as the Muslim Ummah should have specialists in both disciplines.
The eminent Muslim scholar Sheikh Yusuf Al-Qaradawi states the following: The fairest opinion said concerning studying worldly sciences is that issued by Imam Al-Ghazali who said, “If such a science is indispensable to people’s life, then it is considered a collective duty. For example, medicine is a collective duty to be learned, as it is essential for keeping man alive, just as accounting, which is necessary for transactions, dividing inheritance and suchlike. If there is a town that has no specialists in such branches of knowledge, this will cause a great hardship for them. But if there is only one who undertakes this duty and suffices such a town, then the other members of this particular community are not asked to assume this duty.”

It is noteworthy to say that the criterion here is the sufficiency of the number of experts who can meet the needs of their community, for a country may be in need of many persons to take on such responsibilities.
Imam Al-Ghazali continued, “No one should find it odd to say that medicine and accounting are among the collective duties, for the origins of industries such as agriculture, weaving, politics, and even cupping and sewing, and other crafts are all among the collective duties. To illustrate, if there were no cupper in a certain town, they would soon be liable to decay, and they further would be deemed guilty for being exposed to such decay. This is because it is Allah Who sends sickness and it is also He Who sends remedy and guides us to use it, and therefore it is not allowed to be exposed to decay by neglecting the remedy. As for delving into details of mathematics, origins of medicine, and other dispensable knowledge, they are considered only advantages, not legal duties. Acquiring knowledge of such kind is dispensable as stated above; it only raises one’s knowledge of a certain discipline.”
What Al-Ghazali has stated is conclusive and in accordance with the objectives of Shari`ah, which aims at establishing a mighty self-sufficient nation that is able to face its enemies. This makes it necessary for the nation, jointly and severally, to excel in all scientific and mathematical branches of knowledge that nations need nowadays to develop and advance. Nations do not need only medicine and mathematics to progress as Ghazali stated, for he said so with the conditions of his age in mind. In this age of ours, the Muslim Ummah also needs advanced technological industries, not only the old “origins of industries” as Al-Ghazali said. In brief, all that leads to such advanced industries and helps to acquire them is a collective duty on the Muslim Ummah in order for it to not be dependent on others but, rather, self-sufficient.
In these days, the West has mastered the world, including the Islamic world, with the worldly branches of knowledge such as physics, astronomy, chemistry, geology, biology, and other fields. In addition, the West has initiated many revolutions in science, especially in the fields of electronics, space technology, atomic research, genetic engineering, weapons, pharmacology, and other branches. However, because of the separation between religious belief and knowledge in the West, this knowledge has become—in the military field—a danger threatening the whole world with weapons of mass destruction: nuclear, chemical, and biological. Knowledge separated from belief has also given way to the manufacture of unsafe and even illegal drugs, which are marketed by people who neither fear the Creator nor show mercy to the created. People have become afraid of progress in genetics and genetic engineering, technologies that have resulted in cloning animals and might lead to cloning humans.
Undoubtedly, the only solution to this problem is that knowledge be nursed by faith and directed by principles and manners. In fact, this is what Islam provides its followers with; Islam enjoins Muslims to practice only the useful branches of knowledge, not the harmful ones. The Prophet (peace and blessings be upon him) is reported to have sought refuge with Allah from useless knowledge.

Discussing Imam Al-Ghazali’s notion that thorough study of a subject is advantageous rather than obligatory, Sheikh Yusuf Al-Qaradawi further adds:

I disagree with Imam Al-Ghazali in his view that delving into mathematics and the origins of medicine is a mere advantage rather than an obligation; this may apply to his age. But today, studying these sciences and suchlike fields thoroughly is considered an inescapable obligation. This applies to many fields such as mathematics, astronomy, physics, chemistry, geology, biology, oceanography, desert studies, physiology, and other branches. There is a fierce competition between nations in these fields, in which each of them tries to have an advanced position and, at the same time, gives its citizens the chance to excel others in this competition.
had nations not delved into such fields, we would have not witnessed the splitting of the atom, the exploration of space, and the revolutions in computer science, the Internet, IT, biology, communications, and in many other fields. All these achievements have become distinctive characteristics of modern age.
In conclusion, one expert in a certain field may not be sufficient to save the Ummah from sin, for this depends on the needs of the whole Ummah. Generally, the Ummah needs the teamwork of experts in every branch of knowledge to meet Muslims’ need and to pass on their experience to the next generations.