Aristotle’s interaction problem

Aristotle believes that the mind is not a physical entity but derives information from one, which opens him up to the interaction problem. Interestingly, he formulates exactly this problem as the first objection to his theory:

[I]f mind is simple and impassible [i.e. is non-physical] and has nothing in common with anything else [physical], as Anaxagoras says, how can it come to think at all? For interaction between two factors is held to require a precedent community of nature between the factors.

(bracketed text mine.)

Aristotle’s response ties back to the first claim he makes about mind, which can be formalized like this:

1.) Mind detects objects in the world.

2.) One object mind detects is the actual as actual.

3.) No physical organ could detect the actual as actual.

4.) No mind is a physical organ.

Aristotle’s support of #3 is that based on the impossibility of objects being present in the nature of cognitive powers. To the extent that eardrums vibrated by nature they would be worthless for hearing. STA’s theory of medicine gave an illuminating example of this in its theory that the tongue both detected humors in food and could be infected with those same humors during sickness, which made it impossible to taste things as they were (The example is counterfactual for us but no less illustrative). It follows that to detect the actual as such requires being nothing actual by nature. As Aristotle puts it the mind is nothing before it thinks. 

In responding to the interaction problem, he claims:

Have not we already disposed of the difficulty about interaction involving a common element, when we said that mind is in a sense potentially whatever is thinkable, though actually it is nothing until it has thought? What it thinks must be in it just as characters may be said to be on a writing tablet on which as yet nothing actually stands written: this is exactly what happens with mind.

The response can be put in two different forms, both of which turn on the object of mind being the actual as such:

1.) Every interactive system must have an actual structure before it acts

Mind does not have an actual structure before it acts.

2.) Whatever detects the world by interacting with it could not detect the actual as actual

The mind detects the actual as actual.

(Notice that the tabula rasa account of soul means something totally different than it does for Locke. For Aristotle, the point of the metaphor is not to show the vacuity of mind and its dependence on sensation but to show its ontological division from sense cognition.)



  1. David said,

    March 21, 2017 at 1:39 pm

    So, the objection assumes that to detect the world, the mind must interact with it. The response is that it detects the world without interacting? Which still leaves us with no account of “how” the mind detects the world, but perhaps there just isn’t an answer to that in the way I usually answer how-questions (giving an account of interactions).

    You’ve articulated before, the difference between Kant and Aristotle on this point: whether or not the mind is anything before it thinks. What direction could one go to settle that debate?

  2. vetdoctor said,

    March 22, 2017 at 8:37 pm

    So if there is no” how” then why is dualism problematic? Seems like everyone is on equal footing.

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