Of course, science lives by confusing theories, but what were accepted as 'theories' even by the many professional psychologists and psychiatrists were very poor limitations of what physical scientists call a theory.

In theoretical science, the question is—What are we to think? and when a doubtful point arises, for the solution of which either experimental data are wanting, or mathematical methods are not sufficiently advanced, it is the duty of philosophic minds not to dispute about the probability of conflicting suppositions, but to labour for the advancement of experimental inquiry and of mathematics, and await patiently the time when they shall be adequate to solve the question.

There is no logical reason, however, why, in the unfolding of scientific ideas, several theories may not offer alternative but equally valid and important accounts of a particular aspect of nature. Why must some of these theories be rejected almost as a matter of course? It could be objected that if the number of alternative theories became too large, then the whole scientific enterprise would become excessively diffuse and diluted. It is certainly true that without any established limits, ideas do tend to diverge from each other. However, there is also a natural tendency within scientific thinking for ideas to converge as well. Intelligent and creative perception of the different theories may, for example, give rise to new metaphors in which ideas are gathered together and the similarities and differences between them are explored and unfolded.

In sum, a theory is only accepted if the theory has substantial, non-ad hoc, explanatory successes. This is in accordance with Popper; unfortunately, it is in even better accordance with the 'inductivist' accounts that Popper rejects, since these stress support rather than falsification.

A theory, to scientists, means something rather different from its popular use, which suggests something speculative or untested. A scientific theory is a cohesive body of knowledge, an explanation that is consistent among a range of cases and can allow you to predict what might happen in unknown situations.

In the developed sciences, theories tend either to become widely accepted and built into the larger edifice of well-tested human knowledge or else they suffer destruction in the face of recalcitrant facts and are abandoned, perhaps regretfully as a “nice try.” But in fields like personology and social psychology, this seems not to happen. There is a period of enthusiasm about a new theory, a period of attempted application to several fact domains, a period of disillusionment as the negative data come in, a growing bafflement about inconsistent and unreplicable empirical results, multiple resort to ad hoc excuses, and then finally people just sort of lose interest in the thing and pursue other endeavors.

There is a narrowness of action, though not of intent, which characterizes university departments, and scientific publications and scientists in general: if it is too popular, it is somehow vulgar and wrong. You can't really speak to those people across the street. I live next to the chemists at MIT, but I never see them. I hardly know who they are, yet between physics and chemistry it is hard to know who should study what molecule. I myself am guilty. We form communities not based on the problems of science, but on quite other things. This is part of the general split between the intelligent member of the public and the scientist who speaks in narrow focus. But the great theoretical problems which I believe the world expects will somehow be solved by science, problems close to deep philosophical issues are the very problems that find the least expertise, the least degree of organization, the least institutional support in the scientific institutions of America or indeed of the world.

A theory is only as good as its assumptions. If the premises are false, the theory has no real scientific value. The only scientific criterion for judging the validity of a scientific theory is a confrontation with the data of experience.

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.

Wherever there is the slightest possibility for the human mind to know, there is a legitimate problem of science. Outside the field of actual knowledge can only lie a region of the vaguest opinion and imagination, to which... men too often... pay higher respect than to knowledge.

The theory is the result of listening to the problem. When the theory acquires a life of its own because some people like it more than the real world, all kinds of uninspiring, uninteresting things happen, so the key is both to listen to the problem and to study the theory. But always remember that just as much theory is bunk as there are buggy solutions. There is nothing more wrong with "theory" than "solutions" – both their quality and their applicability are orthogonal to their existence.

The effort of the intelligence can aim only at better understanding reflexively the given of faith.[…] All minds, however, do not experience equally the need for such an effort. It is nonetheless very often necessary for them, on the level where their natural speculation usually moves, for dogmas to be given a certain coherent view, more systematized than the teaching of the Church, which renders these dogmas more assimilable to them and which prevents ever-possible deviations. Whence the permanent usefulness of theories that are constructed, through the arrangement of concepts, within common sense, starting with uncriticized representations. Their intellectual value can be weak. To admit them is not, however, pure pragmatism, since they are useful, not for any end whatsoever, but for the maintenance of a truth.… [W]e call to mind one case of this kind by citing the theory of the scientia media: it remains a necessary support for those who need to conceive of the relations between grace and human freedom as an organized system and who could not otherwise preserve the idea of freedom.… [Footnote:] Let us observe, however, that such theories, while they serve to maintain a truth on which attention is fixed, generally thereby compromise a complementary truth, which it is sometimes no less important to hold. We know well enough the weak point in Molinism.

Closely related to the erroneous idea that science is a body of knowledge is the equally erroneous idea that scientific theories are true.

Let us start by considering why the attempt to glorify science on its own cannot work. This is because human thought operates as a whole. It is an ecosphere, a vast and complex landscape, including, but not confined to, common sense. Science itself is, of course, not a single compartment but a large, thickly wooded area comprising many sciences, an area that merges into those around it. Those sciences vary from physics to anthropology and all of them are shot through with problems coming from areas outside them, such as philosophy and history. Biology, for instance, has to deal with philosophical problems about the concept of life and also with vast historical problems about evolution for which it uses historical methods, not those of physics.