The natural as well as the social sciences always start from problems, from the fact that something inspires amazement in us, as the Greek philosophers used to say. To solve these problems, the sciences use fundamentally the same method that common sense employs, the method of trial and error. To be more precise, it is the method of trying out solutions to our problem and then discarding the false ones as erroneous. 
Although I am an admirer of tradition, and conscious of its importance, I am, at the same time, an almost orthodox adherent of unorthodoxy. I hold that orthodoxy is the death of knowledge, since the growth of knowledge depends entirely on the existence of disagreement. Admittedly, disagreement may lead to strife, and even to violence. And this, I think, is very bad indeed, for I abhor violence. Yet disagreement may also lead to discussion, to argument, and to mutual criticism. And these, I think, are of paramount importance. I suggest that the greatest step towards a better and more peaceful world was taken when the war of swords was first supported, and later sometimes even replaced, by a war of words. 
Es gibt ein totales Engagement, das die unvoreingenommene Wahrheitssuche und das kritisch-rationale Denken beseitigt oder zumindest beeinträchtigt und das im Endeffekt – gleichgültig, ob es im Namen des Glaubens und einer göttlichen Macht, im Namen der Geschichte oder in dem der Vernunft in Erscheinung tritt – immer wieder zu totalitären Konsequenzen geführt hat. […] Es kommt hier vielmehr darauf an, daß unter gewissen strukturellen Gesichtspunkten Katholizismus, Kalvinismus, Kommunismus und Faschismus zusammengehören, nicht etwa, weil alle diese historisch sehr komplexen Phänomene in jeder Hinsicht gleichartig oder auch nur gleichwertig wären, sondern weil in ihnen das extreme Gegenteil der im analytischen Denken postulierten Neutralität wirksam war oder ist: die blinde Parteilichkeit, der gehorsame Glaube, das unkorrigierbare Engagement. [5-6]
The myth of the framework can be stated in one sentence, as follows.
A rational and fruitful discussion is impossible unless the participants share a common framework of basic assumptions or, at least, unless they have agreed on such a framework for the purpose of the discussion.
This is the myth I am going to criticize.
As I have formulated it here, the myth sounds like a sober statement, or like a sensible warning to which we ought to pay attention in order to further rational discussion. Some people even think that what I describe as a myth is a logical principle, or based on a logical principle. I think, on the contrary, that it is not only a false statement, but also a vicious statement which, if widely believed, must undermine the unity of mankind, and so must greatly increase the likelihood of violence and of war. This is the main reason why I want to combat it and refute it.
As indicated, I mean by ‘framework’ here a set of basic assumptions, or fundamental principles – that is to say, an intellectual framework. It is important to distinguish such a framework from some attitudes which may indeed be preconditions for a discussion, such as a wish to get to, or nearer to, the truth, and a willingness to share problems or to understand the aims and the problems of somebody else. [34-5]
Serious critical discussions are always difficult. Non-rational human elements such as personal problems always enter. Many participants in a rational, that is, a critical, discussion find it particularly difficult that they have to unlearn what their instincts seem to teach them (and what they are taught, incidentally, by every debating society): that is, to win. For what they have to learn is that victory in a debate is nothing, while even the slightest clarification of one’s problem – even the smallest contribution made towards a clearer understanding of one’s own position or that of one’s opponent – is a great success. A discussion which you win but which fails to help you to change or to clarify your mind at least a little should be regarded as a sheer loss. For this very reason no change in one’s position should be made surreptitiously, but it should always be stressed and its consequences explored.
Rational discussion in this sense is a rare thing. But it is an important ideal, and we may learn to enjoy it. It does not aim at conversion, and it is modest in its expectations: it is enough, more than enough, if we feel that we can see things in a new light or that we have got even a little nearer to the truth. 
I think that we may say of a discussion that it was the more fruitful the more its participants were able to learn from it. And this means: the more interesting questions and difficult questions they were asked, the more new answers they were induced to think of, the more they were shaken in their opinions, and the more they could see things differently after the discussion – in short, the more their intellectual horizons were extended. [35-6]
And yet, I am quite ready to admit that there is a method which might be described as ‘the one method of philosophy’. But it is not characteristic of philosophy alone; it is, rather, the one method of all rational discussion, and therefore of the natural sciences as well as of philosophy. The method I have in mind is that of stating one’s problem clearly and of examining its various proposed solutions critically.
I have italicized the words ‘rational discussion’ and ‘critically’ in order to stress that I equate the rational attitude and the critical attitude. The point is that, whenever we propose a solution to a problem, we ought to try as hard as we can to overthrow our solution, rather than defend it. Few of us, unfortunately, practise this precept; but other people, fortunately, will supply the criticism for us if we fail to supply it ourselves. Yet criticism will be fruitful only if we state our problem as clearly as we can and put our solution in a sufficiently definite form—a form in which it can be critically discussed.
I do not deny that something which may be called ‘logical analysis’ can play a role in this process of clarifying and scrutinizing our problems and our proposed solutions; and I do not assert that the methods of ‘logical analysis’ or ‘language analysis’ are necessarily useless. My thesis is, rather, that these methods are far from being the only ones which a philosopher can use with advantage, and that they are in no way characteristic of philosophy. They are no more characteristic of philosophy than of any other scientific or rational inquiry.
It may perhaps be asked what other ‘methods’ a philosopher might use. My answer is that though there are any number of different ‘methods’, I am really not interested in enumerating them. I do not care what methods a philosopher (or anybody else) may use so long as he has an interesting problem, and so long as he is sincerely trying to solve it. [xix-xx]
Intelligence, then, is the ability to attain goals in the face of obstacles by means of decisions based on rational (truth-obeying) rules. The computer scientists Allen Newell and Herbert Simon fleshed this idea out further by noting that intelligence consists of specifying a goal, assessing the current situation to see how it differs from the goal, and applying a set of operations that reduce the difference. Perhaps reassuringly, by this definition human beings, not just aliens, are intelligent. We have desires, and we pursue them using beliefs, which, when all goes well, are at least approximately or probabilistically true.