Induction and Intuition in Scientific Thought

P B Medawar

• Publisher: Routledge
• Year: 2013
• ISBN:
  9781135028251
• Edition: 1
• Topic: Filosofía
• Subtopic: Historia y teoría filosóficas

Originally published in 1969. This book explains what is wrong with the traditional methodology of "inductive" reasoning and shows that the alternative scheme of reasoning associated with Whewell, Pierce and Popper can give the scientist a useful insight into the way he thinks.

I. THE PROBLEM STATED

1

IT IS NOT at all usual for scientists to deliver formal lectures on the nature of scientific method, particularly if they are still engaged in scientific research. Of course, it is an understood thing that scientists of a specially elevated kind, e.g. theoretical physicists, may from time to time express quietly authoritative opinions on the conduct of scientific enquiry, while the rest of us listen in respectful silence; but that a biologist should speak up where so many physicists and chemists have chosen to remain silent must seem to you to be yet another symptom of the decay of values and the loss, in this modern world, of all sense of the fitness of things.

Yet—if the task of scientific methodology is to piece together an account of what scientists actually do, then the testimony of biologists should be heard with specially close attention. Biologists work very close to the frontier between bewilderment and understanding. Biology is complex, messy and richly various, like real life; it travels faster nowadays than physics or chemistry (which is just as well, since it has so much farther to go), and it travels nearer to the ground. It should therefore give us a specially direct and immediate insight into science in the making. The wisest judgments on scientific method ever made by a working scientist were indeed those of a great biologist, Claude Bernard.¹

We all know in rough outline what lawyers do, or clergymen, physicians, accountants, and civil servants; we have a vague idea of the codes of practice they must abide by if they are to succeed in their professional duties, and if we were to learn more about them we should be edified, no doubt, but not surprised. But what are scientists like as professional men, and how do they set about to enlarge our understanding of the world around us? There seems to be no one answer. The layman’s interpretation of scientific practice contains two elements which seem to be unrelated and all but impossible to reconcile. In the one conception the scientist is a discoverer, an innovator, an adventurer into the domain of what is not yet known or not yet understood. Such a man must be speculative, surely, at least in the sense of being able to envisage what might happen or what could be true. In the other conception the scientist is a critical man, a skeptic, hard to satisfy; a questioner of received beliefs. Scientists (in this second view) are men of facts and not of fancies, and science is antithetical to, perhaps even an antidote to, imaginative activity in all its forms.

Let me begin with the scientist as a questioner of received beliefs. During the seventeenth century, when the new science came in on a spring tide,² and again during the nineteenth century, the forward movement of science called for a vigorous shaking off of scholastic constraints and religious superstition. No single work displays science in its critical temper more clearly than Francis Galton’s Statistical Inquiries into the Efficacy of Prayer, published by the Fortnightly Review in its issue of August 1, 1872.

A belief in the efficacy of prayer (Galton reasoned) is something we all grow up with: it has behind it the formidable authority of habit, doctrine, and popular assent. But are there in fact any “scientific” grounds for supposing that prayers are answered: that what is prayed for comes about as a consequence of an act of prayer? One line of enquiry that seemed to Galton to promise a definite answer turned upon the health and longevity of the Queen and other members of the royal family—something prayed for weekly or even daily on a national scale, and sung for too, though in an imperative rather than a supplicatory mood. Do members of royal families live any longer as a result of these exertions of prayer on their behalf? Table 1, transcribed from Galton’s paper, shows that if anything they fare worse than people of humbler birth.

The amplitude and frequency of prayers for the royal family cannot be assumed to be proportional to their sincerity, so Galton put the same question in a different way. No one can doubt the sincerity of prayers that appeal for the lives of newborn children: are then stillbirths any less frequent among the children of the devout than among the professional classes generally? Apparently not: Galton studied the number of stillbirths announced in The Record (a clerical newspaper) and in The Times, and found them to stand in exactly

TABLE 1
MEAN AGB ATTAINED BY MALES OF VARIOUS CLASSES WHO HAD SURVIVED THEIR THIRTIETH YEAR, FROM 1758 TO 1843.DEATHS BY ACCIDENT OR VIOLENCE EXCLUDED

			Average	Eminent Men^1
Members of Royal houses . . . .	97	in number	64.04
Clergy . . . . . . . . . . . . . . . . . . .	945	“	69.49	66.42
Lawyers . . . . . . . . . . . . . . . . .	294	“	68.14	66.51
Medical Profession . . . . . . . . .	244	“	67.31	67.07
English aristocracy . . . . . . . . . .	1,179	“	67.31
Gentry . . . . . . . . . . . . . . . . . . .	1,632	“	70.22
Trade and commerce . . . . . . . .	513	“	68.74
Officers in the Royal Navy . . . .	366	“	68.40
English literature and science . . .	395	“	67.55	65.22
Officers of the Army . . . . . . . . .	569	“	67.07
Fine Arts . . . . . . . . . . . . . . . . .	239	“	65.96	64.74

¹The eminent men are those whose lives are recorded in Alexander Chalmers’ General Biographical Dictionary (32 vols., London, 1812–1817) with some additions from the Annual Register.

the same proportion to the total number of recorded deaths. The data are shaky, of course, and Galton was quite aware of the shortcomings of his analysis. His purpose was above all to show that such an analysis can in fact be done.

Galton’s most telling argument was founded upon the policy of insurance companies in fixing the rates of annuities. To buy an annuity is to pay a capital sum at (for example) retirement, in return for which the company undertakes to provide the investor with an annual income until he dies. The rates offered by different companies are competitive and must be judiciously worked out, for if the annuitant lives beyond the calculated expectation the insurance company will be out of pocket. This being so,

It would be most unwise, from a business point of view, to allow the devout, supposing their greater longevity even probable, to obtain annuities at the same low rates as the profane. Before insurance offices accept a life, they make confidential inquiries into the antecedents of the applicant. But such a question has never been heard of as, “Does he habitually use family prayers and private devotions?” Insurance offices, so wakeful to sanatory influences, absolutely ignore prayer as one of them. The same is true for insurances of all descriptions, as those connected with fire, ships, lightning, hail, accidental death, and cattle sickness. How is it possible to explain why Quakers, who are most devout and most shrewd men of business, have ignored these considerations, except on the ground that they do not really believe in what they and others freely assert about the efficacy of prayer ?

I have not done justice to the range and analytical skill of Galton’s polished and urbane analysis, and I shall have done him a positive injustice if I leave you with the impression that he was merely having a go at religious belief. The rhetorical force of his argument would have been greatly weakened if it had been crudely irreligious. Prayer, he tells us, may strengthen the resolution and bring serenity in distress; it is an appeal for help; Galton did not “profess to throw light on the question of how far it is possible for man to commune in his heart with God.” His reasoning was thus “scientific” in the territory in which he exercised it, but also in the territory he disclaimed.

Reasoning in this style is by no means confined to or even specially characteristic of scientific enquiry. Galton’s first step was to assume the truth of an opinion for which there was a certain obvious prima facie case, namely that what is prayed for may come about through prayer; then he examined some of the logical consequences of holding that opinion; then, thirdly, he took steps to find out whether or not those logical expectations were indeed fulfilled. The argument was made out by reasoning, not by asseveration; the matters of fact upon which the judgment turned were, if not known, then knowable by everyone; and the testimony of inner voices went unheard. His great achievement was, of course, methodological. He brought within the domain of science matters until then thought to lie outside its competence: “the efficacy of prayer seems to me … a perfectly appropriate and legitimate subject of scientific inquiry.” The reasoning may be empirically wrong, but it is not fallacious; an answer will be arrived at by this style of reasoning or not at all.

The critical task of science is not complete and never will be, for it is the merest truism that we do not abandon mythologies and superstitions but merely substitute new variants for old. No one of Galton’s stature has conducted a statistical enquiry into the efficacy of psychoanalytic treatment. If such a thing were done, might it not show that the therapeutic pretensions of psychoanalysis were not borne out by what it actually achieved? It was perhaps a premonition of what the results of such an enquiry might be that has led modern psychoanalysts to dismiss as somewhat vulgar the idea that the chief purpose of psychoanalytic treatment is to effect a cure. No: its purpose is rather to give the patient a new and deeper understanding of himself and of the nature of his relationship to his fellow men. So interpreted, psychoanalysis is best thought of as a secular substitute for prayer. Like prayer, it is conducted in the form of a duologue, and like prayer (if prayer is to bring comfort and refreshment) it requires an act of personal surrender, though in this case to a professional and stipendiary god.

Nor has anyone yet conducted a formal analysis of the all but universal belief that dreams are messages of some kind; that dreams convey significant information clothed in a dark and ancient symbolism which only the initiated can decode. Analysis, I suspect, would reveal that dreams, whatever else they may be, are not messages or communications of any kind. The utter non-sensicality of dreams—their glorious emancipation from the confinements of time and place and cause and sense—is probably the most significant thing about them, the property from which the student of mind has most to learn. If these newer inquiries were to be set in train, and were to have the outcome I have predicted, the resentment and sense of outrage they would give rise to would be indistinguishable in character and psychological origin from that which exploded nearly one hundred years ago over Galton’s analysis of prayer.

2

The layman’s conception of the scientist as a critic, a skeptic, a man intolerant or contemptuous of conventional beliefs, is obviously incomplete. The exposure and castigation of error does not propel science forward, though it may clear a number of obstacles from its path. To prove that pigs cannot fly is not to devise a machine that does so. To explode the myth of the Chimera make...