The only relevant test of the validity of a hypothesis is comparison of prediction with experience.
Interpretation
A hypothesis is validated by how well its predictions align with actual experience.
Milton Friedman emphasizes that the true test of any hypothesis lies in its ability to make accurate predictions that match real-world experiences. This highlights the importance of empirical evidence in evaluating theories and the need for practical outcomes over mere theoretical consistency.
In practice
This quote can be used in a science class to explain how scientific methods validate hypotheses.
The economic miracle that has been the United States was not produced by socialized enterprises, by government-unon-industry cartels or by centralized economic planning. It was produced by private enterprises in a profit-and-loss system. And losses were at least as important in weeding out failures, as profits in fostering successes. Let government succor failures, and we shall be headed for stagnation and decline.
Universities exist to transmit knowledge and understanding of ideas and values to students not to provide entertainment for spectators or employment for athletes.
There is no place for government to prohibit consumers from buying products the effect of which will be to harm themselves.
There is one and only one social responsibility of business - to use it resources and engage in activities designed to increase its profits so long as it stays within the rules of the game, which is to say, engages in open and free competition without deception or fraud.
The great danger to the consumer is the monopoly -whether private or governmental. His most effective protection is free competition at home and free trade throughout the world. The consumer is protected from being exploited by one seller by the existence of another seller from whom he can buy and who is eager to sell to him. Alternative sources of supply protect the consumer far more effectively than all the Ralph Naders of the world.
The strongest argument for free enterprise is that it prevents anybody from having too much power. Whether that person is a government official, a trade union official, or a business executive. If forces them to put up or shut up. They either have to deliver the goods, produce something that people are willing to pay for, are willing to buy, or else they have to go into a different business.
Science and technology have freed humanity from many burdens and given us this new perspective and great power. This power can be used for the good of all. If wisdom governs our actions; but if the world is mad or foolish, it can destroy itself just when great advances and triumphs are almost without its grasp.
Space or science fiction has become a dialect for our time.
We carry stores of DNA in our nuclei that may have come in, at one time or another, from the fusion of ancestral cells and the linking of ancestral organisms in symbiosis. Our genomes are catalogues of instructions from all kinds of sources in nature, filed for all kinds of contingencies.
If everything in chemistry is explained in a satisfactory manner without the help of phlogiston, it is by that reason alone infinitely probable that the principle does not exist; that it is a hypothetical body, a gratuitous supposition; indeed, it is in the principles of good logic, not to multiply bodies without necessity.
Kidney transplants seem so routine now. But the first one was like Lindbergh's flight across the ocean.
Thus science must begin with myths, and with the criticism of myths; neither with the collection of observations, nor with the invention of experiments, but with the critical discussion of myths, and of magical techniques and practices.
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