Worldviews or schemes of world knowledge (the ways man defines or explains the world) generally fall into three classes: scientific, philosophic, and religious.

Scientific Worldview
Science is based on two things: hypothesis and experiment. In the scientist's mind, to discover and explain a phenomenon, one first forms a hypothesis, and then one subjects in to concrete experiment, in the laboratory. If the experiment supports the hypothesis, it becomes an accepted scientific principle. As long as no more comprehensive hypothesis, better supported by experimentation, appears, that scientific principle retains its standing. The more comprehensive hypothesis with its advent clears the field for itself.

Science thus engages in discovering causes and effects: Through concrete experiments, it discovers a thing's cause or effect; then it pursues the cause of that cause or the effect of that effect. It continues this course of discovery as far as possible.

The work of science, in being based on concrete experiments, has advantages and shortcomings. The greatest advantage of scientific research is that it is exact, precise, and discriminating. Science is able to give man thousands of data about some slight being; it can fill a book with knowledge about a leaf. Because it acquaints man with the special laws of every being, it enables man to control and dominate that being. 'bus, it brings about industry and technology.

But precisely because of these qualities, the compass of science is also limited to experiment. It advances as far as can be subjected to experiment. But can one bring all of being in all its aspects within the confines of experiment? Science in practice pursues causes and effects to a certain limit and then reaches a point where it must say, "I don't know."

Science is like a powerful searchlight in the long winter night, illuminating a certain area without disclosing anything beyond its border. Can one determine by experiment whether the universe has a beginning and an end or is limitless in time? Or does the scientist, on reaching this point, consciously or unconsciously mount the pinions of philosophy in order to express an opinion?

From the standpoint of science, the universe is like an old book the first and last pages of which have been lost. Neither the beginning nor the end is known. Thus, the worldview of science is a knowledge of the part, not of the whole. Our science acquaints us with the situation of some parts of the universe, not with the shape, mien, and character of the whole universe. The scientist's worldview is like the knowledge about the elephant gained by those who touched it in the dark, The one who felt the elephant's ear supposed the animal to be shaped like a fan; the one who felt its leg supposed it to be shaped like a column; and the one who felt its back supposed it to be shaped like a throne.

Another shortcoming of the scientific worldview as a basis for an ideology is that science is unstable and unenduring from a theoretical standpoint, that is, from the standpoint of presenting reality as it is or of auracting faith to the nature of the reality of being. From the viewpoint of science, the face of the world changes from day to day because science is based on hypothesis and experiment, not on rational and self-evident first principles. Hypothesis and experiment have a provisional value; so the scientific worldview is shaky and inconsistent and cannot serve as a foundation for faith. Faith demands a firmer, an unshakeable foundation, a foundation characterised by eternity.

The scientific worldview, in accordance with the limitations that the tools of science (hypothesis and experiment) have inevitably brought about for science, falls short of answering a series of basic cosmological questions that an ideology is obliged to answer decisively, such as: Where did the universe come from? Where is it going? How are we situated within the totality of being? Does the universe have a beginning and an end in time or in space? Is being in its totality right or a mistake, true or vain, beautiful or ugly? Do inevitable and immutable norms preside over the universe, or does no immutable norm exist? Is being in its totality a single living, conscious entity, or is it dead and unconscious, man's existence being an aberration, an accident? Can that which exists cease to exist?

Can that which does not exist come into existence? Is the return of that which has lapsed from existence possible or impossible? Are the universe and history exactly repeatable, even after billions of years (the cyclical theory)? Does unity truly preside, or does multiplicity? Is the universe divisible into the material and the nonmaterial, and is the material universe a small part of the universe as a whole? Is the universe under guidance and seeing, or is it blind? Is the universe transacting with man? Does the universe respond in kind to man's good and evil? Does an enduring life exist after this transient one?

Science arrives at "I don't know" in trying to answer all these questions because it cannot subject them to experiment. Science answers limited, partial questions but is incapable of representing the totality of the universe. An analogy will clarify this point. It is possible for an individual to be well acquainted with a neighbourhood or a quarter of Tehran.

For instance, he may know South Tehran or some part of it in detail, such that he can sketch the streets, alleys, and even the houses of that area from memory. Someone else may know another neighbourhood, a third person, a third area, and soon. If we bring together everything they know, we shall know enough of Tehran, part by part. But if we learn about Tehran in this way, shall we have learned about Tehran from every standpoint? Can we gain a complete picture of Tehran? Is it circular? Is it square? Is it shaped like the leaf of a tree? Of what tree? What relationships do the neighbourhoods have with one another? Which bus lines connect how many neighbourhoods? Is Tehran as a whole beautiful or ugly? If we want to inform ourselves on subjects such as these, if, for instance, we want to learn what the shape of Tehran is, or whether it is beautiful or ugly, we must board a plane and take in the whole city from above. In this sense, science is incapable of answering the most basic questions, as a worldview must; that is, it can form no general conceptions of the universe as a whole and of its form.

The importance of the scientific worldview lies in its practical, technical value, not in its theoretical value. What can serve as the support for an ideology is a theoretical value, not a practical one. The theoretical value of science lies in the reality of the universe being just as it is represented in the mirror of science. The practical and technical value of science lies in science's empowering man in his work and being fruitful, whether or not it represents reality. Today's industry and technology display the practical and technical value of science.

One of the remarkable things about science in today's world is that, to the extent that its practical and technical value increases, its theoretical value diminishes. Those on the sidelines suppose that the progress of science as an illumination of the human conscience and as a source of faith and certitude relative to reality (which is how science represents itself) is in direct proportion to the extent of irrefutable concrete progress, whereas the truth is just the opposite.

An ideology requires a worldview that, first, answers the basic cosmological questions of relevance to the universe as a whole, not just to some certain part; second, provides a well-grounded, reliable, and eternally valid comprehension, not a provisional, transient one; and third, provides something of theoretical, not purely practical and technical value, something revealing reality. The scientific worldview, for all its advantages from other standpoints, fails to fulfil these three conditions.

Philosophical Worldview
Although the philosophical worldview lacks the exactitude and definition of the scientific worldview, it enjoys an assurance and has none of the instability of the scientific worldview. The reason for this is that it rests on a series of principles that are in the first place self-evident and undeniable to the mind, carried forward by demonstration and deduction, and in the second place general and comprehensive (in the language of philosophy, they relate to that by virtue of which the being is being). The worldview of philosophy answers those same questions on which ideologies rest. Philosophical thought discerns the mien of the universe as a whole.

The scientific worldview and the philosophical worldview both conduce to action, but in two different ways. The scientific worldview conduces to action by giving man the power and capacity to "change" and to "control" nature; it allows him to render nature subservient to his own desires. But the philosophical worldview conduces to action and influences action by distinguishing the reasons for action and the criteria for human choice in life.

The philosophical worldview is influential in the way man encounters and responds to the universe. It fixes the attitude of man to the universe and shapes his outlook toward being and the universe. It gives man ideas or takes them away. It imparts meaning to his life or draws him into futility and emptiness. Thus, science is incapable but philosophy is capable of giving man a worldview as the foundation of an ideology.

Religious Worldview
If we regard every general viewpoint expressed toward being and the universe as philosophical, regardless of the source of that worldview (that is, syllogism, demonstration, and deduction or revelation received from the unseen world), we must regard the religious worldview as philosophical. The religious worldview and the philosophic worldview cover the same domain, by contrast with the scientific worldview. But if we take into account the source of knowledge, we must certainly admit that the religious and the philosophical cosmologies are different in kind. In some religions, such as Islam, the religious cosmology within the religion has taken on a philosophical quality, that is, a rational quality.

It relies on reason and deduction and adduces demonstrations in answering the questions that are raised. From this standpoint, the Islamic worldview is likewise a rational and philosophical worldview. Among the advantages of the religious worldview (in addition to the two advantages it shares with the philosophical worldview -stability and eternality, and generality and comprehensiveness) is its sanctification of the bases of the worldview.