The Logical Leap: Q&A with Author David Harriman

Q: In a nutshell, what is induction?

Induction is the process of inferring generalizations from particular instances. Consider an advanced, scientific example: Newton began with observations of particular planets, moons, apples, tides, and comets—and he generalized to arrive at the universal law of gravitation.

Typically, philosophers have been skeptical about this process. The so-called “problem of induction” is usually stated this way: How can we be justified in making a giant “leap” from a relatively few observations to a universal truth?

Q: Is there a “problem of induction”—and if so, how do you attempt to solve it?

I argue in my book that there is no problem of justifying an arbitrary leap—because there is no arbitrary leap. The inference of generalizations from particulars is a perfectly logical process. The problem is not to justify it, but to identify the method of doing it properly.

As the means to that end, I discuss topics ranging from the nature of concepts to the role of experiment and mathematics to the criteria of proof for a theory. My approach is to look closely at the discovery processes of great scientists, and thereby induce the correct principles of method. The result is a theory of induction containing many new points that I hope philosophers, scientists, teachers and students will find interesting.

Q: Do you think that scientists today are following the inductive method you advocate, or are they doing something different?

If they are making valid discoveries, then they are doing so in the way I describe. The theme of my book is not merely that scientists should use this method; rather, I make the stronger claim that they must use this method in order to make progress. And many scientists are making progress, particularly in the applied fields.

In physics today, the main problem is in fundamental theory. For example, many physicists accept string theory because they find it “beautiful,” not because it is induced from observational evidence. As a result, progress in theoretical physics has stagnated for more than a generation.

Q: How did you become interested in the topic of scientific induction?

All of our conceptual knowledge depends on induction, and philosophers since antiquity have struggled with the question of how we can be certain of our inductive generalizations.

Four centuries ago, modern science was born. Since that time, scientists have been enormously successful in their efforts to induce the laws of nature. But philosophers have been unable to explain how and why the scientists have been so successful. I think this is the most crucial question in philosophy of science, so I decided to work on it.

Q: You mention that you took classes from a philosopher who wrote a book titled Against Method. Do you think scientists are getting any help from philosophers today?

No, and that is a tragedy. Scientists are pursuing knowledge, so they need to understand the nature of knowledge and how it is acquired. But philosophers have become skeptics and therefore they have no help to offer. Consequently, most scientists dismiss philosophy as irrelevant to their work. I hope to convince them otherwise.

Q: Could you elaborate on your hopes for The Logical Leap? Who will read it, and what will they learn from it?

I hope that philosophers and their students learn that knowledge is possible, and that their field can offer the fundamental guidance that enables people to identify rational goals and achieve them. And I hope that scientists and their students gain insight into the principles of method that have led to the great discoveries of the past—and will lead to the great discoveries of the future.