We all think we believe what we believe for good reasons – especially philosophers. However, as figures such as Nietzsche, William James and Iris Murdoch have suggested, what we believe may be influenced far more by our psychology and life experiences, rather than by logic and reason, writes David Bryce Yaden and Derek Anderson.

How do philosophers come to endorse one view over another? One might imagine an impartial analysis of the merits of various arguments. Indeed, we don’t doubt that this accounts for the majority of the process. But what other influences­­––perhaps more psychological––should we consider? That is the question that we explored in our new paper, “The Psychology of Philosophy.” [1]

One potential influence on a given philosopher’s views may be their personality or other psychological traits. Does a philosopher’s disposition relate to complicated philosophical views, such as whether free will exists, whether one endorses deontological or consequentialist ethical views, or whether morality and aesthetics are objective or subjective? These questions are not new.

In Beyond Good and Evil, in a section called “The Prejudices of Philosophers” Nietzsche writes:

"They all pose as though their real opinions had been discovered and attained through the self-evolving of a cold, pure, divinely indifferent dialectic (in contrast to all sorts of mystics, who, fairer and foolisher, talk of "inspiration"), whereas, in fact, a prejudiced proposition, idea, or "suggestion," which is generally their heart's desire abstracted and refined, is defended by them with arguments sought out after the event…It has gradually become clear to me what every great philosophy up till now has consisted of--namely, the confession of its originator, and a species of involuntary and unconscious auto-biography”

Does a philosopher’s disposition relate to complicated philosophical views?

In Pragmatism, William James writes:

“The history of philosophy is to a great extent that of a certain clash of human temperaments. Undignified as such a treatment may seem to some of my colleagues, I shall have to take account of this clash and explain a good many of the divergencies of philosophers by it. Of whatever temperament a professional philosopher is, he tries when philosophizing to sink the fact of his temperament. Temperament is no conventionally recognized reason, so he urges impersonal reasons only for his conclusions. Yet his temperament really gives him a stronger bias than any of his more strictly objective premises.”

In The Sovereignty of Good, Iris Murdoch writes:

“To do philosophy is to explore one’s own temperament and yet at the same time to discover the truth. It seems to me that there is a void in present-day moral philosophy…A working philosophical psychology is needed...”

One might wonder whether it is significant that each of these philosophers who drew special attention to the role of temperament in philosophy also had substantial interdisciplinary expertise or training. Before writing now classic works of philosophy, Nietzsche was a professor of philology at the University of Basel with a focus on historical texts from Greece. James had a medical degree and was a founder of empirical psychology before becoming a professor of philosophy at Harvard. Murdoch taught philosophy at Oxford and was an acclaimed novelist.