The Floating Man
A thought experiment about a floating man evokes questions about causation and the soul.


This week we are thinking about causation. Imagine this with us: you wake into an existence for the very first time and you’re falling through the air at 200 km/h. What are your first thoughts? Can you conceptualise what’s happening? Are you even aware of yourself? The first thoughts of a sperm whale falling into an alien planet in The Hitchhiker’s Guide to the Galaxy are: ‘Ah . . . ! What’s happening?’ Perhaps yours are the same.

Avicenna, a Persian philosopher of the Islamic Golden Age, considered this situation in his famous ‘floating-man’ thought experiment. In his version of events a man is permanently suspended in air and deprived of all his senses since birth. Until now he hasn’t experienced anything.

Yet, Avicenna said, while the man doesn’t know what’s happening, he has primordial knowledge of himself: he was born with a concept of being (‘knowledge by presence’). Avicenna, therefore, posited the idea of innate knowledge, which exists through a transcendent self or ‘soul’, separately from the body and our sense experience.

The idea of innate knowledge sits in opposition to the views on causation of David Hume, who argued that we gain knowledge through experience alone. Hence, according to Hume, The Floating Man could not know himself. Moreover, he cannot know that X causes Y because he hasn’t experienced X’s relation to Y before. So The Floating Man does not understand what’s going on around him either.

However, there’s an issue with Hume’s position: the predictive power of babies! Authors of scientific studies (e.g. Muentener and Carey 2010) have reported how they perform tasks correctly without ever being taught. Thus babies apparently exert causal control on the external world before experiencing it.

Who’s right? While a transcendent self or soul may sound outlandish, babies having innate knowledge is an imaginable problem for David Hume’s notion of causation, according to which knowledge of causal relations in the world (which aren’t really causal since we represent them as causal) is learned.

The question boils down to: are we born with relevant knowledge of the world or not?