Islamic economics in practice, or economic policies supported by self-identified Islamic groups, has varied throughout its long history. Traditional Islamic concepts having to do with economics included
These concepts, like others in Islamic law and jurisprudence, came from the "prescriptions, anecdotes, examples, and words of the Prophet, all gathered together and systematized by commentators according to an inductive, casuistic method."  Sometimes other sources such as al-urf, (the custom), al-aql (reason) or al-ijma (consensus of the jurists) were employed. In addition, Islamic law has developed areas of law that correspond to secular laws of contracts and torts.
Some argue early Islamic theory and practice formed a "coherent" economic system with "a blueprint for a new order in society, in which all participants would be treated more fairly". Michael Bonner, for example, has written that an "economy of poverty" prevailed in Islam until the 13th and 14th centuries. Under this system God's guidance made sure the flow of money and goods was "purified" by being channeled from those who had much of it to those who had little by encouraging zakat (charity) and discouraging riba (usury/interest) on loans. Bonner maintains the prophet also helped poor traders by allowing only tents, not permanent buildings in the market of Medina, and not charging fees and rents there.
Social responsibility and corporate social responsibility in commerce was stressed in Islamic sociology. The development of Islamic banks and Islamic economics was a side effect of this sociology: usury was rather severely restrained, no interest rate was allowed, and investors were not permitted to escape the consequences of any failed venture—all financing was equity financing (Musharaka). In not letting borrowers bear all the risk/cost of a failure, an extreme disparity of outcomes between "partners" is thus avoided. Ultimately this serves a social harmony purpose. Muslims also could not and cannot (in shariah) finance any dealings in forbidden goods or activities, such as wine, pork, gambling, etc. Thus ethical investing is the only acceptable investing, and moral purchasing is encouraged.
The Hawala, an early informal value transfer system, has its origins in classical Islamic law, and is mentioned in texts of Islamic jurisprudence as early as the 8th century. Hawala itself later influenced the development of the agency in common law and in civil laws such as the aval in French law and the avallo in Italian law. The words aval and avallo were themselves derived from Hawala. The transfer of debt, which was "not permissible under Roman law but became widely practiced in medieval Europe, especially in commercial transactions", was due to the large extent of the "trade conducted by the Italian cities with the Muslim world in the Middle Ages." The agency was also "an institution unknown to Roman law" as no "individual could conclude a binding contract on behalf of another as his agent." In Roman law, the "contractor himself was considered the party to the contract and it took a second contract between the person who acted on behalf of a principal and the latter in order to transfer the rights and the obligations deriving from the contract to him." On the other hand, Islamic law and the later common law "had no difficulty in accepting agency as one of its institutions in the field of contracts and of obligations in general."
The waqf in Islamic law, which developed in the medieval Islamic world from the 7th to 9th centuries, bears a notable resemblance to the English trust law. Every waqf was required to have a waqif (founder), mutawillis (trustee), qadi (judge) and beneficiaries. Under both a waqf and a trust, "property is reserved, and its usufruct appropriated, for the benefit of specific individuals, or for a general charitable purpose; the corpus becomes inalienable; estates for life in favor of successive beneficiaries can be created" and "without regard to the law of inheritance or the rights of the heirs; and continuity is secured by the successive appointment of trustees or mutawillis."
The only significant distinction between the Islamic waqf and English trust was "the express or implied reversion of the waqf to charitable purposes when its specific object has ceased to exist", though this difference only applied to the waqf ahli (Islamic family trust) rather than the waqf khairi (devoted to a charitable purpose from its inception). Another difference was the English vesting of "legal estate" over the trust property in the trustee, though the "trustee was still bound to administer that property for the benefit of the beneficiaries." In this sense, the "role of the English trustee therefore does not differ significantly from that of the mutawalli."
The trust law developed in England at the time of the Crusades, during the 12th and 13th centuries, was introduced by Crusaders who may have been influenced by the waqf institutions they came across in the Middle East.
After the Islamic waqf law and madrassah foundations were firmly established by the 10th century, the number of Bimaristan hospitals multiplied throughout throughout Islamic lands. In the 11th century, every Islamic city had at least several hospitals. The waqf trust institutions funded the hospitals for various expenses, including the wages of doctors, ophthalmologists, surgeons, chemists, pharmacists, domestics and all other staff, the purchase of foods and remedies; hospital equipment such as beds, mattresses, bowls and perfumes; and repairs to buildings. The waqf trusts also funded medical schools, and their revenues covered various expenses such as their maintenance and the payment of teachers and students.
During the Islamic Golden Age, guilds were formed though officially unrecognized by the medieval Islamic city. However, trades were recognized and supervised by officials of the city. Each trade developed its own identity, whose members would attend the same mosque, and serve together in the militia.
Technology and industry in Islamic civilization were highly developed. Distillation techniques supported a flourishing perfume industry, while chemical ceramic glazes were developed constantly to compete with ceramics imported from China. A scientific approach to metallurgy made it easier to adopt and improve steel technologies from India and China. Primary exports included manufactured luxuries, such as wood carving, metal and glass, textiles, and ceramics.
The systems of contract relied upon by merchants was very effective. Merchants would buy and sell on commission, with money loaned to them by wealthy investors, or a joint investment of several merchants, who were often Muslim, Christian and Jewish. Recently, a collection of documents was found in an Egyptian synagogue shedding a very detailed and human light on the life of medieval Middle Eastern merchants. Business partnerships would be made for many commercial ventures, and bonds of kinship enabled trade networks to form over huge distances. Networks developed during this time enabled a world in which money could be promised by a bank in Baghdad and cashed in Spain, creating the cheque system of today. Each time items passed through one of the cities along this extraordinary network, the city imposed a tax, resulting in high prices once the items reached their final destinations. These innovations made by Muslims and Jews laid the foundations for the modern economic system.
Transport was simple, yet highly effective. Each city had an area outside its gates where pack animals were assembled; found in the cities' markets were large secure warehouses; while accommodations were provided for merchants in cities and along trade routes by a sort of medieval motel.
The concepts of welfare and pension were introduced in early Islamic law as forms of Zakat (charity), one of the Five Pillars of Islam, since the time of the Abbasid caliph Al-Mansur in the 8th century. The taxes (including Zakat and Jizya) collected in the treasury of an Islamic government was used to provide income for the needy, including the poor, elderly, orphans, widows, and the disabled. According to the Islamic jurist Al-Ghazali (Algazel, 1058–1111), the government was also expected to store up food supplies in every region in case a disaster or famine occurs. The Caliphate was thus one of the earliest welfare states, particularly the Abbasid Caliphate.
The Islamic Empire significantly contributed to globalization during the Islamic Golden Age, when the knowledge, trade and economies from many previously isolated regions and civilizations began integrating due to contacts with Muslim explorers, sailors, scholars, traders, and travelers. Some have called this period the "Pax Islamica" or "Afro-Asiatic age of discovery", in reference to the Muslim South-west Asian and North African traders and explorers who travelled most of the Old World, and established an early global economy across most of Asia and Africa and much of Europe, with their trade networks extending from the Atlantic Ocean and Mediterranean Sea in the west to the Indian Ocean and China Sea in the east. This helped establish the Islamic Empire (including the Rashidun, Umayyad, Abbasid and Fatimid caliphates) as the world's leading extensive economic power throughout the 7th-13th centuries. Several contemporary medieval Arabic reports also suggest that Muslim explorers from al-Andalus and the Maghreb may have travelled in expeditions across the Atlantic Ocean between the 9th and 14th centuries.
Arabic silver dirham coins were being circulated throughout the Afro-Eurasian landmass, as far as sub-Saharan Africa in the south and northern Europe in the north, often in exchange for goods and slaves. In England, for example, the Anglo-Saxon king Offa of Mercia (r. 757-796) had coins minted with the Shahadah in Arabic. These factors helped establish the Arab Empire (including the Rashidun, Umayyad, Abbasid and Fatimid caliphates) as the world's leading extensive economic power throughout the 7th–13th centuries.
During the Muslim Agricultural Revolution, the Caliphate understood that real incentives were needed to increase productivity and wealth, thus enhancing tax revenues, hence they introduced a social transformation through the changed ownership of land, where any individual of any gender or any ethnic or religious background had the right to buy, sell, mortgage and inherit land for farming or any other purposes. They also introduced the signing of a contract for every major financial transaction concerning agriculture, industry, commerce, and employment. Copies of the contract were usually kept by both parties involved.
The two types of economic systems that prompted agricultural development in the Islamic world were either politically-driven, by the conscious decisions of the central authority to develop under-exploited lands; or market-driven, involving the spread of advice, education, and free seeds, and the introduction of high value crops or animals to areas where they were previously unknown. These led to increased subsistence, a high level of economic security that ensured wealth for all citizens, and a higher quality of life due to the introduction of artichokes, spinach, aubergines, carrots, sugar cane, and various exotic plants; vegetables being available all year round without the need to dry them for winter; citrus and olive plantations becoming a common sight, market gardens and orchards springing up in every Muslim city; intense cropping and the technique of intensive irrigation agriculture with land fertility replacement; a major increase in animal husbandry; higher quality of wool and other clothing materials; and the introduction of selective breeding of animals from different parts of the Old World resulting in improved horse stocks and the best load-carrying camels.
Hundreds of crops were diffused throughout the Islamic world and beyond as a result of the Muslim Agricultural Revolution. Some of these included artichokes, bananas, coconut palms, colocasia, cotton, eggplants, hard wheat, lemons, limes, mangos, plantains, rice, sorghum, sour oranges, spinach, sugar cane, and watermelons, among hundreds of other crops.
The Islamic Empire experienced a growth in literacy, having the highest literacy rate of the Middle Ages, comparable to Athens' literacy in Classical Antiquity but on a larger scale. The average life expectancy in the lands under Islamic rule also experienced an increase, due to the Agricultural Revolution as well as improved medical care. In contrast to the average lifespan in the ancient Greco-Roman world (22–28 years), the average lifespan in the early Islamic Caliphate was more than 35 years. The average lifespans of the Islamic scholarly class in particular was much higher: 84.3 years in 10th-11th century Iraq and Persia, 72.8 years in the 11th century Middle East, 69–75 years in 11th century Islamic Spain, 75 years in 12th century Persia, and 59–72 years in 13th century Persia.
A number of innovative concepts and techniques were introduced in early Islamic commerce, including bills of exchange, forms of partnership (mufawada) such as limited partnerships (mudaraba), and early forms of capital (al-mal), capital accumulation (nama al-mal), cheques, promissory notes, trusts (see Waqf), startup companies,, transactional accounts, loaning, ledgers and assignments. Organizational enterprises similar to corporations independent from the state also existed in the medieval Islamic world, while the agency institution was also introduced. Many of these early concepts were adopted and further advanced in medieval Europe from the 13th century onwards.
A market economy was established in the Islamic world on the basis of an economic system resembling merchant capitalism. Capital formation was promoted by labour in medieval Islamic society, and financial capital was developed by a considerable number of owners of monetary funds and precious metals. Riba (usury) was prohibited by the Qur'an, but this did not hamper the development of capital in any way. The capitalists (sahib al-mal) were at the height of their power between the 9th–12th centuries, but their influence declined after the arrival of the ikta (landowners) and after production was monopolized by the state, both of which hampered the development of industrial capitalism in the Islamic world. Some state enterprises and government-owned corporations still had a capitalist mode of production, such as pearl diving in Iraq and the textile industry in Egypt.
During the 11th–13th centuries, the "Karimis", an early multinational corporation, enterprise and business group controlled by entrepreneurs, came to dominate much of the Islamic world's economy. The group was controlled by about fifty Muslim merchants labelled as "Karimis" who were of Yemeni, Egyptian and sometimes Indian origins. Each Karimi merchant had considerable wealth, ranging from at least 100,000 dinars to as much as 10 million dinars. The group had considerable influence in most important eastern markets and sometimes in politics through its financing activities and through a variety of customers, including Emirs, Sultans, Viziers, foreign merchants, and common consumers. The Karimis dominated many of the trade routes across the Mediterranean Sea, Red Sea, and Indian Ocean, and as far as Francia in the north, China in the east, and sub-Saharan Africa in the south, where they obtained gold from gold mines. Innovations introduced by the Karimis include the use of agents, the financing of projects as a method of acquiring capital, and a banking institution for loans and deposits. Another important difference between the Karimis and other entrepreneurs before and during their time was that they were not tax collectors or landlords, but their capitalism was due entirely to trade and financial transactions.
Though medieval Islamic economics appears to have somewhat resembled a form of capitalism, some arguing that it laid the foundations for the development of modern capitalism, some Orientalists also believe that there exist a number of parallels between Islamic economics and communism, including the Islamic ideas of zakat and riba. Others see Islamic economics as neither completely capitalistic nor completely socialistic, but rather a balance between the two, emphasizing both "individual economic freedom and the need to serve the common good."
Muslim engineers in the Islamic world were responsible for numerous innovative industrial uses of hydropower, early industrial uses of tidal power, wind power, fossil fuels such as petroleum, and early large factory complexes (tiraz in Arabic). A variety of industrial mills were used in the Islamic world, including fulling mills, gristmills, hullers, sawmills, shipmills, stamp mills, steel mills, sugar mills, tide mills, and windmills. By the 11th century, every province throughout the Islamic world had these industrial mills in operation, from al-Andalus and North Africa to the Middle East and Central Asia. Muslim engineers also invented water turbines, first employed gears in mills and water-raising machines, and pioneered the use of dams as a source of water power, used to provide additional power to watermills and water-raising machines. Such advances made it possible for many industrial tasks that were previously driven by manual labour in ancient times to be mechanized and driven by machinery instead in the medieval Islamic world. The transfer of these technologies to medieval Europe later laid the foundations for the Industrial Revolution in 18th century Europe.
Many industries were generated due to the Muslim Agricultural Revolution, including the earliest industries for agribusiness, astronomical instruments, ceramics, chemicals, distillation technologies, clocks, glass, mechanical hydropowered and wind powered machinery, matting, mosaics, pulp and paper, perfumery, petroleum, pharmaceuticals, rope-making, shipping, shipbuilding, silk, sugar, textiles, weapons, and the mining of minerals such as sulfur, ammonia, lead and iron]. The first large factory complexes (tiraz) were built for many of these industries. Knowledge of these industries were later transmitted to medieval Europe, especially during the Latin translations of the 12th century, as well as before and after. For example, the first glass factories in Europe were founded in the 11th century by Egyptian craftsmen in Greece. The agricultural and handicraft industries also experienced high levels of growth during this period.
In Islamic governments such as the Fatimid Caliphate, the tax collection, rather than being wasted on temples or courts, was invested industrial development, such as the Fatimid government's investment in the textile industry. In addition to government-owned tiraz textile factories, there were also privately-owned enterprises run largely by landlords who collected taxes and invested them in the textile industry.
The labor force in the Caliphate were employed from diverse ethnic and religious backgrounds, while both men and women were involved in diverse occupations and economic activities. Women were employed in a wide range of commercial activities and diverse occupations in the primary sector (as farmers for example), secondary sector (as construction workers, dyers, spinners, etc.) and tertiary sector (as investors, doctors, nurses, presidents of guilds, brokers, peddlers, lenders, scholars, etc.). Muslim women also held a monopoly over certain branches of the textile industry, the largest and most specialized and market-oriented industry at the time, in occupations such as spinning, dying, and embroidery. In comparison, female property rights and wage labour were relatively uncommon in Europe until the Industrial Revolution in the 18th and 19th centuries.
The division of labour was diverse and had been evolving over the centuries. During the 8th–11th centuries, there were on average 63 unique occupations in the primary sector of economic activity (extractive), 697 unique occupations in the secondary sector (manufacturing), and 736 unique occupations in the tertiary sector (service). By the 12th century, the number of unique occupations in the primary sector and secondary sector decreased to 35 and 679 respectively, while the number of unique occupations in the tertiary sector increased to 1,175. These changes in the division of labour reflect the increased mechanization and use of machinery to replace manual labour and the increased standard of living and quality of life of most citizens in the Caliphate.
An economic transition occurred during this period, due to the diversity of the service sector being far greater than any other previous or contemporary society, and the high degree of economic integration between the labour force and the economy. Islamic society also experienced a change in attitude towards manual labour. In previous civilizations such as ancient Greece and in contemporary civilizations such as early medieval Europe, intellectuals saw manual labour in a negative light and looked down on them with contempt. This resulted in technological stagnation as they did not see the need for machinery to replace manual labour. In the Islamic world, however, manual labour was seen in a far more positive light, as intellectuals such as the Brethren of Purity likened them to a participant in the act of creation, while Ibn Khaldun alluded to the benefits of manual labour to the progress of society.
There was a significant increase in urbanization during this period, due to numerous scientific advances in fields such as agriculture, hygiene, sanitation, astronomy, medicine and engineering. This also resulted in a rising middle class population.
As urbanization increased, Muslim cities grew unregulated, resulting in narrow winding city streets and neighborhoods separated by different ethnic backgrounds and religious affiliations. These qualities proved efficient for transporting goods to and from major commercial centers while preserving the privacy valued by Islamic family life. Suburbs lay just outside the walled city, from wealthy residential communities, to working class semi-slums. City garbage dumps were located far from the city, as were clearly defined cemeteries which were often homes for criminals. A place of prayer was found just near one of the main gates, for religious festivals and public executions. Similarly, Military Training grounds were found near a main gate.
While varying in appearance due to climate and prior local traditions, Islamic cities were almost always dominated by a merchant middle class. Some peoples' loyalty towards their neighborhood was very strong, reflecting ethnicity and religion, while a sense of citizenship was at times uncommon (but not in every case). The extended family provided the foundation for social programs, business deals, and negotiations with authorities. Part of this economic and social unit were often the tenants of a wealthy landlord.
State power normally focused on Dar al Imara, the governor's office in the citadel. These fortresses towered high above the city built on thousands of years of human settlement. The primary function of the city governor was to provide for defence and to maintain legal order. This system would be responsible for a mixture of autocracy and autonomy within the city. Each neighborhood, and many of the large tenement blocks, elected a representative to deal with urban authorities. These neighborhoods were also expected to organize their young men into a militia providing for protection of their own neighborhoods, and as aid to the professional armies defending the city as a whole.
The head of the family was given the position of authority in his household, although a qadi, or judge was able to negotiate and resolve differences in issues of disagreements within families and between them. The two senior representatives of municipal authority were the qadi and the muhtasib, who held the responsibilities of many issues, including quality of water, maintenance of city streets, containing outbreaks of disease, supervising the markets, and a prompt burial of the dead.
Another aspect of Islamic urban life was waqf, a religious charity directly dealing with the qadi and religious leaders. Through donations, the waqf owned many of the public baths and factories, using the revenue to fund education, and to provide irrigation for orchards outside the city. Following expansion, this system was introduced into Eastern Europe by Ottoman Turks.
While religious foundations of all faiths were tax exempt in the Muslim world, civilians paid their taxes to the urban authorities, soldiers to the superior officer, and landowners to the state treasury. Taxes were also levied on an unmarried man until he was wed. Instead of zakat, the mandatory charity required of Muslims, non-Muslims were required to pay the jizya, a discriminatory religious tax, imposed on Christians and Jews. During the Muslim Conquests of the 7th and 8th centuries conquered populations were given the three choices of either converting to Islam, paying the jizya, or dying by the sword.
Animals brought to the city for slaughter were restricted to areas outside the city, as were any other industries seen as unclean. The more valuable a good was, the closer its market was to the center of town. Because of this, booksellers and goldsmiths clustered around the main mosque at the heart of the city.
By the 10th century, Cordoba had 700 mosques, 60,000 palaces, and 70 libraries, the largest of which had 600,000 books, while as many as 60,000 treatises, poems, polemics and compilations were published each year in al-Andalus. The library of Cairo had more than 100,000 books, while the library of Tripoli is said to have had as many as three million books. The number of important and original Arabic works on science that have survived is much larger than the combined total of Greek and Latin works on science.
The concepts of welfare and pension were introduced in early Islamic law as forms of Zakat (charity), one of the Five Pillars of Islam, during the time of the Rashidun caliph Umar in the 7th century. This practiced continued well into the era of the Abbasid Caliphate, as seen under Al-Ma'mun's rule in the 8th century, for example. The taxes (including Zakat and Jizya) collected in the treasury of an Islamic government were used to provide income for the needy, including the poor, elderly, orphans, widows, and the disabled. According to the Islamic jurist Al-Ghazali (Algazel, 1058–1111), the government was also expected to stockpile food supplies in every region in case a disaster or famine occurred. The Caliphate is thus considered the world's first major welfare state.
The origins of economics can be traced back to the work of the ancient Indian scholar-philosopher Chanakya, who laid down what is arguably the earliest writings of concepts concerning economics in the 4th century BC.
Al-Ghazali (1058–1111) classified economics as one of the sciences connected with religion, along with metaphysics, ethics, and psychology. Authors have noted, however, that this connection has not caused early Muslim economic thought to remain static. Persian philosopher Nasir al-Din al-Tusi (1201–1274) presents an early definition of economics (what he calls hekmat-e-madani, the science of city life) in discourse three of his Ethics:
"the study of universal laws governing the public interest (welfare?) in so far as they are directed, through cooperation, toward the optimal (perfection)."
Many scholars trace the history of economic thought through the Muslim world, which was in a Golden Age from the 8th to 13th century and whose philosophy continued the work of the Greek and Hellenistic thinkers and came to influence Aquinas when Europe "rediscovered" Greek philosophy through Arabic translation. A common theme among these scholars was the praise of economic activity and even self-interested accumulation of wealth. Persian leader Shams al-Mo'ali Abol-hasan Ghaboos ibn Wushmgir (Qabus) (died 1012) advises his son in the work Qabus nama:
"My son, do not be indifferent to the acquisition of wealth. Assure yourself that everything you acquire shall be the best quality and is likely to give you pleasure."
Persian philosopher Ibn Miskawayh (b. 1030) notes:
"The creditor desires the well-being of the debtor in order to get his money back rather than because of his love for him. The debtor, on the other hand, does not take great interest in the creditor."
This view is in conflict with an idea Joseph Schumpeter called the great gap. The great gap thesis comes out of Schumpeter's 1954 History of Economic Analysis which discusses a break in economic thought during the five hundred year period between the decline of the Greco-Roman civilizations and the work of Thomas Aquinas (1225–1274). However in 1964, Joseph Spengler's "Economic Thought of Islam: Ibn Khaldun" appeared in the journal Comparative Studies in Society and History and took a large step in bringing early Muslim scholars to the attention of the contemporary West.
The influence of earlier Greek and Hellenistic thought on the Muslim world began largely with Abbasid caliph al-Ma'mun, who sponsored the translation of Greek texts into Arabic in the 9th century by Syrian Christians in Baghdad. But already by that time numerous Muslim scholars had written on economic issues, and early Muslim leaders had shown sophisticated attempts to enforce fiscal and monetary financing, use deficit financing, use taxes to encourage production, the use of credit instruments for banking, including rudimentary savings and checking accounts, and contract law.
Among the earliest Muslim economic thinkers was Abu Yusuf (731-798), a student of the founder of the Hanafi Sunni School of Islamic thought, Abu Hanifah. Abu Yusuf was chief jurist for Abbasid Caliph Harun al-Rashid, for whom he wrote the Book of Taxation (Kitab al-Kharaj). This book outlined Abu Yusuf's ideas on taxation, public finance, and agricultural production. He discussed proportional tax on produce instead of fixed taxes on property as being superior as an incentive to bring more land into cultivation. He also advocated forgiving tax policies which favor the producer and a centralized tax administration to reduce corruption. Abu Yusuf favored the use of tax revenues for socioeconomic infrastructure, and included discussion of various types of taxes, including sales tax, death taxes, and import tariffs.
Early discussion of the benefits of division of labor are included in the writings of Qabus, al-Ghazali, al-Farabi (873–950), Ibn Sina (Avicenna) (980–1037), Ibn Miskawayh, Nasir al-Din al-Tusi (1201–74), Ibn Khaldun (1332–1406), and Asaad Davani (b. 1444). Among them, the discussions included division of labor within households, societies, factories, and among nations. Farabi notes that each society lacks at least some necessary resources, and thus an optimal society can only be achieved where domestic, regional, and international trade occur, and that such trade can be beneficial to all parties involved. Ghazali was also noted for his subtle understanding of monetary theory and formulation of another version of Gresham's Law.
"If desire for goods increases while its availability decreases, its price rises. On the other hand, if availability of the good increases and the desire for it decreases, the price comes down."
Ghazali suggests an early version of price inelasticity of demand for certain goods, and he and Ibn Miskawayh discuss equilibrium prices. Other important Muslim scholars who wrote about economics include al-Mawardi (1075–1158), Ibn Taimiyah (1263–1328), and al-Maqrizi.
The common view of riba (usury) among classical jurists of Islamic law and economics during the Islamic Golden Age was that it is only riba and therefore unlawful to apply interest to money exnatura sua—exclusively gold and silver currencies—but that it is not riba and is therefore acceptable to apply interest to fiat money—currencies made up of other materials such as paper or base metals—to an extent.
The definition of riba in classical Islamic jurisprudence was "surplus value without counterpart." When "currencies of base metal were first introduced in the Islamic world, no jurist ever thought that paying a debt in a higher number of units of this fiat money was riba" as they were concerned with the real value of money rather than the numerical value. For example, it was acceptable for a loan of 1000 gold dinars to be paid back as 1050 dinars of total equal mass. The rationale behind riba according to classical Islamic jurists was "to ensure equivalency in real value" and that the "numerical value was immaterial." Thus an interest rate that did not exceed the rate of inflation was not riba according to classical Islamic jurists.
|When civilization [population] increases, the available labor again increases. In turn, luxury again increases in correspondence with the increasing profit, and the customs and needs of luxury increase. Crafts are created to obtain luxury products. The value realized from them increases, and, as a result, profits are again multiplied in the town. Production there is thriving even more than before. And so it goes with the second and third increase. All the additional labor serves luxury and wealth, in contrast to the original labor that served the necessity of life.|
|Ibn Khaldun on economic growth|
Perhaps the most well known Islamic scholar who wrote about economics was Ibn Khaldun of Tunisia (1332–1406), who is considered a forerunner of modern economics. Ibn Khaldun wrote on economic and political theory in the introduction, or Muqaddimah (Prolegomena), of his History of the World (Kitab al-Ibar). In the book, he discussed what he called asabiyya (social cohesion), which he sourced as the cause of some civilizations becoming great and others not. Ibn Khaldun felt that many social forces are cyclic, although there can be sudden sharp turns that break the pattern. His idea about the benefits of the division of labor also relate to asabiyya, the greater the social cohesion, the more complex the successful division may be, the greater the economic growth. He noted that growth and development positively stimulates both supply and demand, and that the forces of supply and demand are what determines the prices of goods. He also noted macroeconomic forces of population growth, human capital development, and technological developments effects on development. In fact, Ibn Khaldun thought that population growth was directly a function of wealth.
Although he understood that money served as a standard of value, a medium of exchange, and a preserver of value, he did not realize that the value of gold and silver changed based on the forces of supply and demand. He also introduced the concept known as the Khaldun-Laffer Curve (the relationship between tax rates and tax revenue increases as tax rates increase for a while, but then the increases in tax rates begin to cause a decrease in tax revenues as the taxes impose too great a cost to producers in the economy).
"In the early stages of the state, taxes are light in their incidence, but fetch in a large revenue...As time passes and kings succeed each other, they lose their tribal habits in favor of more civilized ones. Their needs and exigencies grow...owing to the luxury in which they have been brought up. Hence they impose fresh taxes on their subjects...and sharply raise the rate of old taxes to increase their yield...But the effects on business of this rise in taxation make themselves felt. For business men are soon discouraged by the comparison of their profits with the burden of their taxes...Consequently production falls off, and with it the yield of taxation."
This analysis anticipates the modern economic concept known as the Laffer Curve.
Ibn Khaldun also introduced the labor theory of value. He described labor as the source of value, necessary for all earnings and capital accumulation, obvious in the case of craft. He argued that even if earning “results from something other than a craft, the value of the resulting profit and acquired (capital) must (also) include the value of the labor by which it was obtained. Without labor, it would not have been acquired.”
His theory of asabiyyah has often been compared to modern Keynesian economics, with Ibn Khaldun's theory clearly containing the concept of the multiplier. A crucial difference, however, is that whereas for John Maynard Keynes it is the middle class's greater propensity to save that is to blame for economic depression, for Ibn Khaldun it is the governmental propensity to save at times when investment opportunities do not take up the slack which leads to aggregate demand.
Another modern economic theory anticipated by Ibn Khaldun is supply-side economics. He "argued that high taxes were often a factor in causing empires to collapse, with the result that lower revenue was collected from high rates." He wrote:
"It should be known that at the beginning of the dynasty, taxation yields a large revenue from small assessments. At the end of the dynasty, taxation yields a small revenue from large assessments."
During the modern post-colonial era, as Western ideas, including Western economics, began to influence the Muslim world, some Muslim writers sought to produce an Islamic discipline of economics. Because Islam is "not merely a spiritual formula but a complete system of life in all its walks", it logically followed that Islam also had its own economic system unique from and superior to non-Islamic systems. To date, however, there have been no agreement as to the methodological definition and scope of Islamic Economics.
In the 1960s and 70s Shia Islamic thinkers worked to develop a unique Islamic economic philosophy with "its own answers to contemporary economic problems." Several works were particularly influential,
Al-Sadr in particular has been described as having "almost single-handedly developed the notion of Islamic economics" 
In their writings Sadr and the other Shia authors "sought to depict Islam as a religion committed to social justice, the equitable distribution of wealth, and the cause of the deprived classes," with doctrines "acceptable to Islamic jurists", while refuting existing non-Islamic theories of capitalism and Marxism. This version of Islamic economics, which influenced the Iranian Revolution, called for public ownership of land and of large "industrial enterprises," while private economic activity continued "within reasonable limits."  These ideas helped shape the large public sector and public subsidy policies of the Iranian Islamic revolution.
In the 1980s and 1990s, as the Iranian revolution failed to reach the per capita income level achieved by the regime it overthrew, and Communist states and socialist parties in the non-Muslim world turned away from socialism, Muslim interest shifted away from government ownership and regulation. In Iran, it is reported that "eqtesad-e Eslami (meaning both Islamic economics and economy) ... once a revolutionary shibboleth, is indubitably absent in all official documents and the media. It disapperared from Iranian political discourse about 15 years ago ." 
But in other parts of the Muslim world the term lived on, shifting form to the less ambitious goal of interest-free banking. Some Muslim bankers and religious leaders suggested ways to integrate Islamic law on usage of money with modern concepts of ethical investing. In banking this was done through the use of sales transactions (focusing on the fixed rate return modes) to achieve similar results to interest. This has been criticised by some western writers as a means of covering conventional banking with an Islamic facade.
While most Muslims believe Islamic law is perfect by virtue of its being revealed by God, Islamic law on economic issues was/is not "economics" in the sense of a systematic study of production, distribution, and consumption of goods and services.
In modern times, economic policies of the 1979 Islamic Revolution in predominately Shia Iran were heavily statist with a very large public sector, and official rhetoric celebrating revolution and the rights of the dispossessed, although this tendency has faded over time. In Sudan, the policies of the National Islamic Front party dominated regime in the 1990s have been the reverse, employing economic liberalism and accepting "market forces in the formulation of state policies." In Algeria, Jordan, Egypt, and Pakistan, Islamist parties have supported populist policies, showing a "marked reluctance to adopt austerity policies and decreased subsidies."  In recent years, Turkey had a rapidly growing economy and became a developed country according to the CIA. Indonesia, Saudi Arabia and Turkey are members of the G-20 major economies.
In 2008, at least $500 billion in assets around the world were managed in accordance with Sharia, or Islamic law, and the sector was growing at more than 10% per year. Islamic finance seeks to promote social justice by banning exploitative practices. In reality, this boils down to a set of prohibitions—on paying interest, on gambling with derivatives and options, and on investing in firms that make pornography or pork.
Another form of modern finance that originated from the Muslim world is microcredit and microfinance. It began in the Indian Subcontinent with the AKDN in the 1860s and followed in Bangladesh with Grameen Bank, founded by Muhammad Yunus, recipient of the 2006 Nobel Peace Prize.
One issue "generally absent" from contemporary Islamist economic thought (with the exception of Sayyid Qutb) and action "whether moderate or radical" is the question of agrarian reform. Opposition to agrarian reform even played a role in Islamist uprisings (Iran 1963, Afghanistan, 1978). At least one observor (Olivier Roy) believes this is primarily because it would "imply a reexamination of the concept of ownership", and in particular "throw into question the Waqf, endowments whose revenue ensures the functioning of religious institutions." In the Islamic Republic of Iran, for example, waaf holdings are very large (in Khorasan Province, "50% of the cultivated lands belong to the religious foundation Astan-i Quds, which oversees" the Imam Reza shrine in Mashhad). Thus questioning waaf property would mean questioning "the foundation of the financial autonomy of the mullahs and mosques", particularly among Shia Muslims.