Mu (logic)

A term borrowed from Zen Buddhism, used as an avoidant answer to decision-making questions (yes/no questions) to indicate that the question cannot be answered because the implied premises do not hold.

There is no direct equivalent to the term in English, but phrases like “yes and no” can sometimes be used in situations where both “yes” and “no” would be possible, but neither is entirely appropriate.

— Is it true that there are no speed limits at all on German motorways?
— Yes and no – there’s no general speed limit, but of course there are local speed limits …

Unlike “yes and no”, as used here, “Mu” implies that the question is based on premises which would already be wrong to accept. To capture the meaning of “Mu” even more accurately, one could vary the example slightly:

– Is it true that there’s no speed limit on motorways in Liechtenstein either?
– Mu! Liechtenstein does not have any motorways to begin with¹⁾.

The term “Mu” originates from Japanese (Kanji: 無, or Hiragana: む) and refers to the absence of something. In this context, it can be translated as “nothing” or “without”.

Mu is a central concept in Zen Buddhist philosophy, used to highlight the limitations of a dualistic worldview. Similar concepts in Western philosophy include the continuum fallacy and the false dilemma.

In this sense, the term was popularised in the Western world primarily through Douglas Hofstadter’s book “Gödel, Escher, Bach”.

Strictly speaking, this is not a concept native to (classical) logic, but rather a pragmatic linguistic concept; nevertheless, it can help us to better understand certain logical problems.

• Continuum fallacy
• False dilemma

• Mu (negative) on Wikipedia