Thomas Aquinas in the context of "Classical theism"

European science in the Middle Ages comprised the study of nature, mathematics and natural philosophy in medieval Europe. Following the fall of the Western Roman Empire and the decline in knowledge of Greek, Christian Western Europe was cut off from an important source of ancient learning. Although a range of Christian clerics and scholars from Isidore and Bede to Jean Buridan and Nicole Oresme maintained the spirit of rational inquiry, Western Europe would see a period of scientific decline during the Early Middle Ages. However, by the time of the High Middle Ages, the region had rallied and was on its way to once more taking the lead in scientific discovery. Scholarship and scientific discoveries of the Late Middle Ages laid the groundwork for the Scientific Revolution of the Early Modern Period.

According to Pierre Duhem, who founded the academic study of medieval science as a critique of the Enlightenment theory of a 17th-century anti-Aristotelian and anticlerical scientific revolution, the various conceptual origins of that alleged revolution lay in the 12th to 14th centuries, in the works of churchmen such as Thomas Aquinas and Buridan.

Subsidiarity is a principle of social organization that holds that social and political issues should be dealt with at the most immediate or local level that is consistent with their resolution. The Oxford English Dictionary defines subsidiarity as "the principle that a central authority should have a subsidiary function, performing only those tasks which cannot be performed at a more local level". The concept is applicable in the fields of government, political science, neuropsychology, cybernetics, management and in military command (mission command). The OED adds that the term "subsidiarity" in English follows the early German usage of "Subsidiarität". More distantly, it is derived from the Latin verb subsidio (to aid or help), and the related noun subsidium (aid or assistance).

The development of the concept of subsidiarity has roots in the natural law philosophy of Thomas Aquinas and was mediated by the social scientific theories of Luigi Taparelli, SJ, in his 1840–43 natural law treatise on the human person in society. In that work, Taparelli established the criteria of just social order, which he referred to as "hypotactical right" and which came to be termed "subsidiarity" following German influences.

Latin literature includes the essays, histories, poems, plays, and other writings written in the Latin language. The beginning of formal Latin literature dates to 240 BC, when the first stage play in Latin was performed in Rome. Latin literature flourished for the next six centuries. The classical era of Latin literature can be roughly divided into several periods: early Latin literature, the golden age, the imperial period and Late Antiquity.

Latin was the language of the ancient Romans as well as being the lingua franca of Western and Central Europe throughout the Middle Ages. Latin literature features the work of Roman authors, such as Cicero, Virgil, Ovid and Horace, but also includes the work of European writers after the fall of the Empire, from religious writers like Aquinas (1225–1274) to secular writers like Francis Bacon (1561–1626), Baruch Spinoza (1632–1677), and Isaac Newton (1642–1727).

Avicennism is a school of Islamic philosophy which was established by Avicenna. He developed his philosophy throughout the course of his life after being deeply moved and concerned by the Metaphysics of Aristotle and studying it for over a year. According to Henry Corbin and Seyyed Hossein Nasr, there are two kinds of Avicennism: Islamic Avicennism, and Latin Avicennism.

According to Nasr, the Latin Avicennism was based on the former philosophical works of Avicenna. This school followed the Peripatetic school of philosophy and tried to describe the structure of reality with a rational system of thinking. In the twelfth century AD, it became influential in Europe, particularly in Oxford and Paris, and affected some notable philosophers such as Thomas Aquinas, Roger Bacon and Duns Scotus. While the Latin Avicennism was weak in comparison with Latin Averroism, according to Étienne Gilson there was an "Avicennising Augustinism".

Natural law (Latin: ius naturale, lex naturalis) is a philosophical and legal theory that posits the existence of a set of inherent laws derived from nature and universal moral principles, which are discoverable through reason. In ethics, natural law theory asserts that certain rights and moral values are inherent in human nature and can be understood universally, independent of enacted laws or societal norms. In jurisprudence, natural law—sometimes referred to as iusnaturalism or jusnaturalism—holds that there are objective legal standards based on morality that underlie and inform the creation, interpretation, and application of human-made laws. This contrasts with positive law (as in legal positivism), which emphasizes that laws are rules created by human authorities and are not necessarily connected to moral principles. Natural law can refer to "theories of ethics, theories of politics, theories of civil law, and theories of religious morality", depending on the context in which naturally-grounded practical principles are claimed to exist.

In Western tradition, natural law was anticipated by the pre-Socratics, for example, in their search for principles that governed the cosmos and human beings. The concept of natural law was documented in ancient Greek philosophy, including Aristotle, and was mentioned in ancient Roman philosophy by Cicero. References to it are also found in the Old and New Testaments of the Bible, and were later expounded upon in the Middle Ages by Christian philosophers such as Albert the Great and Thomas Aquinas. The School of Salamanca made notable contributions during the Renaissance.

In philosophy, economics, and political science, the common good (also commonwealth, common weal, general welfare, or public benefit) is either what is shared and beneficial for all or most members of a given community, or alternatively, what is achieved by citizenship, collective action, and active participation in the realm of politics and public service. The concept of the common good differs significantly among philosophical doctrines. Early conceptions of the common good were set out by Ancient Greek philosophers, including Aristotle and Plato. One understanding of the common good rooted in Aristotle's philosophy remains in common usage today, referring to what one contemporary scholar calls the "good proper to, and attainable only by, the community, yet individually shared by its members."

The concept of common good developed through the work of political theorists, moral philosophers, and public economists, including Thomas Aquinas, Niccolò Machiavelli, John Locke, Jean-Jacques Rousseau, James Madison, Adam Smith, Karl Marx, John Stuart Mill, John Maynard Keynes, John Rawls, and many other thinkers. In contemporary economic theory, a common good is any good which is rivalrous yet non-excludable, while the common good, by contrast, arises in the subfield of welfare economics and refers to the outcome of a social welfare function. Such a social welfare function, in turn, would be rooted in a moral theory of the good (such as utilitarianism). Social choice theory aims to understand processes by which the common good may or may not be realized in societies through the study of collective decision rules. Public choice theory applies microeconomic methodology to the study of political science in order to explain how private interests affect political activities and outcomes.

Istislah (Arabic: استصلاح, lit. 'to deem proper') is a method employed by Islamic jurists to solve problems that find no clear answer in sacred religious texts. It is related to the term مصلحة Maslaha, or "public interest" (both words being derived from the same triconsonantal root, "ṣ-l-ḥ"). Extratextual pragmatic considerations are commonly accepted in Islamic jurisprudence concerning areas where the Qur'an and the practices of the earliest Muslim generations (Salaf) provide no specific guidance.

Istislah bears some similarities to the natural law tradition in the West, as exemplified by Thomas Aquinas. However, whereas natural law deems good that which is known self-evidently to be good, according as it tends towards the fulfilment of the person, istislah calls good whatever is connected to one of five "basic goods". Al-Ghazali abstracted these "basic goods" from the five legal precepts in the Qur'an and Sunnah—religion, life, reason, lineage (or offspring), and property. In this classical formulation, istislah differs from utilitarianism—"the greatest happiness for the greatest number of people"—because something that results in "the greatest happiness" may infringe any one of the five basic values. Rather than utilitarianism, Istislah bears closer resemblance to deontologicalism.

The Divine Comedy (Italian: Divina Commedia, pronounced [diˈviːna komˈmɛːdja]) is an Italian narrative poem by Dante Alighieri, begun c. 1308 and completed around 1321, shortly before the author's death. It is widely considered the pre-eminent work in Italian literature and one of the greatest works of Western literature. The poem's imaginative vision of the afterlife is representative of the medieval worldview as it existed in the Western Church by the 14th century. It helped establish the Tuscan language, in which it is written, as the standardized Italian language. It is divided into three parts: Inferno, Purgatorio, and Paradiso.

The poem explores the condition of the soul following death and portrays a vision of divine justice, in which individuals receive appropriate punishment or reward based on their actions. It describes Dante's travels through Hell, Purgatory, and Heaven. Allegorically, the poem represents the soul's journey towards God, beginning with the recognition and rejection of sin (Inferno), followed by the penitent Christian life (Purgatorio), which is then followed by the soul's ascent to God (Paradiso). Dante draws on medieval Catholic theology and philosophy, especially Thomistic philosophy derived from the Summa Theologica of Thomas Aquinas.