I am arguing that science can, in principle, help us understand what we would do and should want - and, therefore, what other people should do and should want in order to live the best lives possible. My claim is that there are right and wrong answers to moral questions, just as there are right and wrong answers to questions of physics, and such answers may on day fall within reach of the maturing sciences of mind.

The aim of science is to seek the simplest explanations of complex facts. We are apt to fall into the error of thinking that the facts are simple because simplicity is the goal of our quest. The guiding motto in the life of every natural philosopher should be, "Seek simplicity and distrust it."

There is an inescapable moral dimensions of human existence. It follows that investigation must take account of that proposition. Yet psychologists have been among the most determined opponents of this claim, predictably in the name of what they deem to be science. They hope, at least in their technical activities, to be above the fray.

Psychological despotism, whether enlightened or not, is gross misuse of psychology. The main purpose of psychology is to acquire insight into, and mastery of, oneself. Not for nothing were what we now call the behavioral sciences originally called the moral sciences and “Know thyself” their main precept. To use psychology to control, dominate, and manipulate others is self-destructive abuse of knowledge. It is also a particularly repugnant form of tyranny.

The primary aim of science is to find... new truth. The search is the more successful the more it is directed towards... truth for its own sake, regardless of... possible use or application. ...If everything given to us by research were to be taken away, civilization would collapse and we would stand naked, searching for caves again.

To spread healthy ideas among even the lowest classes of people, to remove men from the influence of prejudice and passion, to make reason the arbiter and supreme guide of public opinion; that is the essential goal of the sciences; that is how science will contribute to the advancement of civilization, and that is what deserves protection of governments who want to insure the stability of their power.

The word 'policy' generally refers to the principles that govern action directed towards given ends. Any study of policy therefore should concern itself with three things — what we want (the ends), how we get it (the means), and who are 'we,' that is, what is the nature of the organization or group concerned. Science is concerned with means rather than with ends. The study of "what we want" (objectives) extends beyond the boundaries of the social sciences into the field of ethics. It is not the business of the social sciences to evaluate the ultimate ends of human activity. The social sciences, therefore, cannot give a final answer to the question whether any given policy is right. The social scientist can study what people say they want, what they think they want and may even infer from their behaviour what they really want, but it is not the business of science to say whether people want right things.

The purpose of science is to describe the world in an orderly scheme or language which will help us to look ahead. We want to forecast what we can of the future behaviour of the world; particularly we want to forecast how it would behave under several alternative actions of our own between which we are usually trying to choose.

The purpose of science in understanding who we are as humans is not to rob us of our sense of mystery, not to cure us of our sense of mystery. The purpose of science is to constantly reinvent and reinvigorate that mystery. To always use it in a context where we are helping people in trying to resist the forces of ideology that we are all familiar with.

If, then, there is some end of the things we do, which we desire for its own sake (everything else being desired for the sake of this), and if we do not choose everything for the sake of something else (for at that rate the process would go on to infinity, so that our desire would be empty and vain), clearly this must be the good and the chief good. Will not the knowledge of it, then, have a great influence on life? Shall we not, like archers who have a mark to aim at, be more likely to hit upon what is right? If so, we must try, in outline at least, to determine what it is, and of which of the sciences or capacities it is the object. It would seem to belong to the most authoritative art and that which is most truly the master art. And politics appears to be of this nature; for it is this that ordains which of the sciences should be studied in a state, and which each class of citizens should learn and up to what point they should learn them; and we see even the most highly esteemed of capacities to fall under this, e.g. strategy, economics, rhetoric; now, since politics uses the rest of the sciences, and since, again, it legislates as to what we are to do and what we are to abstain from, the end of this science must include those of the others, so that this end must be the good for man. For even if the end is the same for a single man and for a state, that of the state seems at all events something greater and more complete whether to attain or to preserve; though it is worth while to attain the end merely for one man, it is finer and more godlike to attain it for a nation or for city-states. These, then, are the ends at which our inquiry aims, since it is political science, in one sense of that term.

Moral Philosophy is the Science of human duty. The knowledge of human duty implies a knowledge of human nature. To understand what man ought to do, it is necessary to know what man is. Not that the Moral Philosopher, before entering upon those inquiries which peculiarly belong to him, must go over the Science of human nature in all its extent. But it is necessary to examine those elements of human nature which have a direct bearing upon human conduct.

You may ask — you are bound to ask me now: What, then, is in your opinion the value of natural science? I answer: Its scope, aim and value is the same as that of any other branch of human knowledge. Nay, none of them alone, only the union of all of them, has any scope or value at all, and that is simply enough described: it is to obey the command of the Delphic deity: gnothi seauton... get to know yourself!

The purpose of scientific enquiry is not to compile an inventory of factual information, nor to build up a totalitarian world picture of natural Laws in which every event that is not compulsory is forbidden. We should think of it rather as a logically articulated structure of justifiable beliefs about nature.

Our aim as scientists is objective truth; more truth, more interesting truth, more intelligible truth. We cannot reasonably aim at certainty. Once we realize that human knowledge is fallible, we realize also that we can never be completely certain that we have not made a mistake.