The most important aim of science is to increase understanding – a second objective is to promote international competitiveness, and more generally so-called social relevance. Understanding is linked, in turn, to explanation: we have a problem or a conundrum, a phenomenon that fails to fit our conceptual framework or even contradicts our expectations. Nonetheless, what is it to understand and explain something scientifically?

From the 1920s, research on the topic was dominated almost exclusively by the so-called deductive-nomological model or covering law model: explanations are based on natural laws and are thus objective, independent of the researcher’s deductive conclusions. If a description of a phenomenon can be derived from laws or descriptions of events preceding that phenomenon then our understanding increases. Thus, explanations are objective and intersubjective; moreover, understanding does not depend on the beliefs let alone interests of the inquirer.

In the 1960s, a group of critics of the model nevertheless claimed entirely the opposite. Explanations are subjective because they are tailored to the interests and beliefs of the recipient. There is no one way of understanding; rather, there is a potpourri of ways of understanding. What works for one, does not work for another! Scientific understanding is inevitably context-dependent, and it depends on who is explaining, to whom, in what situation, and also on the background assumptions of the listener – or so it is claimed.

I have strived to develop the kind of theory that, in the right way, combines objectivity and the element of subjectivity inevitably connected with understanding. Explanations have a question-answer structure familiar from everyday life. Answers can nevertheless vary because of discipline-specific demands. For example, the so-called functional explanations common to biology (the function of the heart is to pump blood), and particularly evolutionary narratives, promote the increase of a different kind of understanding from, for example, the kind of intention explanations used in the humanities or purely physical causal explanations. Explanations are thus similar in their question-answer structure but otherwise constitute a rather heterogeneous family.

It is easy to combine scientific explanation with a tangential theme. Scientific explanations are answers to the questions why and how. In terms of so-called wh-questions (who, where, how many, how long etc.), the thinking is clear. As the father of Finnish question and answer logic, Jaakko Hintikka, put it, an answer is satisfactory when, combined with the questioner’s background information, it enables him or her to identify the referent of a question in terms of person, place, number or duration. Although the answer might be context-dependent (if a person’s name is mentioned, it is not necessarily sufficient to identify that person!), it is not subjective in the sense that the information itself is subjective or coloured in any significant way.

The starting point of the interrogative model of scientific explanation is that the logic of questions and answers can reach to why and how questions. The problem is that the answers, i.e. scientific explanations are often long. In contrast to who (is this person) questions, the questioner does not offer the answerer a ready-made group or even category from which the answer can be selected. Why questions, particularly those involving scientific conundrums, cannot be delineated beforehand in such a way that a sufficient answer would be the name of a person or place. In science, the problem is often what the problem is and how it can be conceptualised in such a way that an answer can be sought.

My own collaboration with Hintikka began in Chicago. We were speaking at the same session and he presented the claim that his question-answer logic really did stretch to why questions and thus offered a foundation for a theory of explanation. The scholar thus presents questions to nature. I disagreed. A scientist can certainly ask nature questions, but they are yes/no or wh-questions in a test series. This is because nature does not understand why questions!

Later, when he was applying to Boston University, I often took him to the airport. While waiting for his plane, we outlined together an application to the Academy of Finland on the topic.