Let us suppose that an ichthyologist is exploring the life of the ocean. He casts a net into the water and brings up a fishy assortment. Surveying his catch, he [concludes that no] sea-creature is less than two inches long. An onlooker may object that the generalization is wrong. "There are plenty of sea-creatures under two inches long, only your net is not adapted to catch them." The ichthyologist dismisses this objection contemptuously: "Anything uncatchable by my net is ipso facto outside the scope of ichthyological knowledge, and is not part of the kingdom of fishes which has been defined as the theme of ichthyological knowledge. In short, what my net can't catch isn't fish”.
Suppose that a more tactful onlooker makes a rather different suggestion: "I realize that you are right in refusing our friend's hypothesis of uncatchable fish, which cannot be verified by any tests you and I would consider valid. By keeping to your own method of study, you have reached a generalization of the highest importance—to fishmongers, who would not be interested in generalizations about uncatchable fish. Since these generalizations are so important, I would like to help you. You arrived at your generalization in the traditional way by examining the fish. May I point out that you could have arrived more easily at the same generalization by examining the net and the method of using it?"So,you see my point? Tools determine knowledge. Period.