The theory of knowledge is inseparable from the theory of life. They must unite so that each may move the other forward.

A theory of knowledge is an answer to the question "What is knowledge?" This question, like many which are asked by philosophers, sounds very simple. We all know, at least roughly, what knowledge is. But difficulties appear the moment that we begin to fill in the details.

To adequately understand evolution, you not only have to understand how to be scientific, (which is the real trick for most people) but you also have to know something about cellular biology, genetics, and anatomy, geology, particularly paleontology, as well as environmental systems, tectonics, atomic chemistry, and especially taxonomy, which most people don’t know squat about at all. Most people who accept evolution also tend to know a whole lot about cosmology, geography, history, sociology, politics, and of course, religion. But to believe in creationism, you don’t have to know anything about anything, and its better if you don’t! Because creationism relies on ignorance. It is not honest research! It is a scam, a con job exploiting the common folk, and preying on their deepest beliefs and fears. Creationist apologetics depends on misrepresented data and misquoted authorities, out-of-date and out-of-context, and uses distorted definitions if it uses definitions at all.

Is evolution a theory, a system or a hypothesis? It is much more: it is a general condition to which all theories, all hypotheses, all systems must bow and which they must satisfy henceforward if they are to be thinkable and true. Evolution is a light illuminating all facts, a curve that all lines must follow.

The science of life has nowadays to a certain extent become a crossroad, in which the contemporary intellectual developments converge. The biological theories have acquired a tremendous ideological [weltanschauliche], yes even public and political significance... The condition of biology, problematic in many respects, has led to the situation that the “philosophies of life” were until now by no means satisfactory from the scientific as much as the practical point of view; we see all the more clearly the importance of the theoretical clarification of biology.

The Theory of Evolution, like the Theory of Gravity, is a scientific fact. Evolution really happened. Accepting our kinship with all life on earth is not only solid science, in my view, it's also a soaring spiritual experience. (From the second Cosmos: ASO episode, Some of the Things That Molecules Do.)

Biologists, or rather botanists and zoologists, studied flora and fauna in exhaustive detail, in niches, in situ, penetrating the mysteries of their local habitations, measuring them, counting them, tracking cycles, writing all this down in the equivalent of field guides, and developing the ability to predict many natural phenomena, including phenomena of change: if frost falls, the bud is harmed; if the soil is enriched, growth improves, and so on. The world of life forms was a text whose meaning the biologist interpreted. But these interpretations did not explain and were not meant to explain the biological processes according to which these species could exist in the first place, or descend, or develop, or differ. To explain these more basic issues required the theory of evolution, which, once it was available, became an indispensable instrument in the professional study of local, narrowly coordinated, in situ life forms and the niches they inhabit.

Having eliminated the soul, modern science cannot understand the body in its most important aspect, which is its capacity for self-importance. Modern biology, particularly the theory of evolution, is based on the overriding concern for survival in all life. This is surely wrong in regard to human life. If you cannot look around you and must insist on indulging a taste for the primitive, you have only to visit the ruins of an ancient people and ponder how much of its GNP was devoted to religion, to its sense of the meaning of human life rather than mere survival.

The struggle for existence holds as much in the intellectual as in the physical world. A theory is a species of thinking, and its right to exist is coextensive with its power of resisting extinction by its rivals.

Theories rarely arise as patient inferences forced by accumulated facts. Theories are mental constructs potentiated by complex external prods (including, in idealized cases, a commanding push from empirical reality). But the prods often include dreams, quirks, and errors—just as we may obtain crucial bursts of energy from foodstuffs or pharmaceuticals of no objective or enduring value. Great truth can emerge from small error. Evolution is thrilling, liberating, and correct. And Macrauchenia is a litoptern.

A theory, is a body of knowledge, that is supportive of, and explanative of facts. Scientific laws are included within a theory, facts are included within a theory, that's why you have the theory of evolution, the theory of gravity, the theory of relativity. There is no concept in creationism, which meets any of the qualifications of a scientific theory, none. You have no facts, you have no laws, you have no evidence, you have no explanative power. All you have, is whatever science can't explain, you pretend you can.

science asks us to learn about organisms, traditional knowledge asks us to learn from them.

But a theory is not like an airline or bus timetable. We are not interested simply in the accuracy of its predictions. A theory also serves as a base for thinking. It helps us to understand what is going on by enabling us to organize our thoughts. Faced with a choice between a theory which predicts well but gives us little insight into how the system works and one which gives us this insight but predicts badly, I would choose the latter, and I am inclined to think that most economists would do the same.

(...) New knowledge has led to the recognition of the theory of evolution as more than a hypothesis. It is indeed remarkable that this theory has been progressively accepted by researchers, following a series of discoveries in various fields of knowledge. The convergence, neither sought nor fabricated, of the results of work that was conducted independently is in itself a significant argument in favor of this theory.