Brentano on the mental

What distinguishes the mental from the non-mental?  Franz Brentano (1838-1917), in Psychology from an Empirical Standpoint, famously takes intentionality to be the key.  He developed this answer by way of criticism of (what he took to be) the traditional Cartesian criterion.  Descartes held that the essence of matter lies in extension and spatial location.  Whatever lacks these geometrical features is therefore non-material.  Accordingly, it must fall into the second class of substances recognized by Descartes, namely mental substance.  As Brentano reads the Cartesian tradition, then, it holds that the essence of the mental is to be unextended and non-spatial.

Brentano argues that this criterion is problematic insofar as there are apparent counterexamples.  For one thing, there are physical phenomena that are arguably neither extended nor spatial.  He notes that sounds and odors are possible examples cited by some of the psychologists of his day.  For another thing, there are mental phenomena that are evidently extended or spatially located.  For example, sense perception is associated with specific bodily organs, and pains and other sensations are located in specific parts of the body.  Brentano doesn’t necessarily endorse all of these examples, but he thinks that the very fact that the criterion of appealing to extension and spatial location (or the lack thereof) is controversial shows that the criterion is inadequate.  Furthermore, he says, it is a purely negative criterion.  A positive characterization of the mental is desirable. 

I’ll get to Brentano’s own proposed criterion in a moment, but let’s pause to evaluate what he says about the purportedly Cartesian criterion.  I’m not a Cartesian, but if I were I’d find Brentano’s remarks pretty annoying, because I don’t think they get Descartes right, and are problematic in other ways too.  First and least importantly (and as Brentano himself might have agreed) the first set of alleged counterexamples is pretty unimpressive.  It’s true that sounds and odors lack the precise spatial locations and boundaries that (say) shapes and color patches have, but they are also clearly locatable and extended in a looser sense.  For example, if someone burns popcorn in the microwave, there is an obvious sense in which the smell of it is located in the kitchen but not in the driveway, and in which the range of the odor might extend to the nearest bedroom but (say) not to the farthest bedroom.  A sound will also be audible only within a certain distance, and its source localizable.  These sorts of facts are enough to make sounds and odors extended and spatially locatable by Descartes’ lights.

A second problem, though, is that Descartes would hold that to say that odors and sounds have extension and spatial location is in any event to speak ambiguously.  For example, he would point out that by “sound,” we might mean compression waves in the air, or we might instead mean the auditory experience these waves cause in us.  If we mean the former, then a sound clearly does have a spatial location.  If we mean the latter, then Descartes would agree that it does not have a spatial location, but would also say that it is not physical in the first place (though note the qualification he would make vis-à-vis sensory experiences that I’ll describe below).

A third and more important problem is that it just isn’t true that Descartes lacks a positive conception of the mental or that he takes the lack of extension and spatial location to be the essence of the mental.  Rather, the essence of the mental is thought -- what remains when you’ve doubted away everything else as a dream, a hallucination caused by an evil spirit, etc., but can still know that cogito, ergo sum.  To be a mind is just to be a thing that thinks, a res cogitans, and there is nothing more to its essence than that.  It is true, of course, that Descartes takes the mind to be unextended and non-spatial, and thus to be immaterial.  But that is not because these features are themselves the essence of the mental.  Rather, he takes them to follow from the essence of the mental, and in particular from the fact (as he sees it) that thought might still exist even if extension and space were fictions.  Of course, we might reasonably go on to ask Descartes what thought is, but the point is that whatever he might say about that, his criterion of what makes something a mind is (i) a positive one, and (ii) not stated in terms of the lack of extension and spatial location. 

A fourth problem is that Descartes would take the other alleged counterexamples cited by Brentano to be characterized in a tendentious way.  For the experiences associated with sensory perception and with pain and other bodily sensations are not, in Descartes’ view, mental full stop.  Again, for Descartes to be a mind is to be a thing that thinks, a res cogitans, and what he primarily associates “thinking” with is intellectual activity, the sort that involves the grasp of concepts which might be expressed in language, etc.  The capacity for sensation (and also for appetite and emotion) he takes to arise only when the res cogitans gets conjoined to the body (the res extensa or extended substance). 

A sensation, then (whether a visual sensation, a sensation of pain, or whatever) is therefore a kind of hybrid attribute in Descartes’ view.  It has both mental and non-mental or physical aspects.  That a sensation of pain has a conscious feel to it is certainly a mental aspect of it, and is contributed by the res cogitans.  But that it has a location (in the back, say) is a non-mental aspect of the sensation, and is contributed by the res extensa.  Hence to cite sensations as purported examples of mental phenomena having extension and spatial location would in Descartes’ view be conceptually sloppy or at least question-begging.

So, Brentano’s critique of the Cartesian position seems to me weak.  What about his own alternative?  Again, Brentano’s claim is that what truly sets the mental apart from everything else is intentionality -- the way a thought, for example, is directed at, “points” to, or is about something.  For instance, the thought that the cat is on the mat is about the cat and its being on the mat, is directed toward that alleged state of affairs or “points” toward it.  Nothing physical is like that, Brentano thinks.  Hence to be mental is, essentially to be intentional, and to be physical is to be non-intentional.  (Remember that “intentional” here is being used in a technical sense.  Brentano isn’t talking about e.g. whether you did something intentionally or unintentionally.  “Intentions” in that ordinary sense are just one manifestation of intentionality in Brentano’s sense.  To be intentional in the relevant technical sense is to exhibit “aboutness” or “directedness toward” an object, and to be non-intentional in the relevant sense is to lack this directedness or aboutness.)

What should we think of this criterion?  One problem with it is that, at least as Brentano states it, it is no less subject to alleged counterexamples than the pseudo-Cartesian criterion he criticizes.  And ironically (given Brentano’s own use of them against the Cartesian view), some would take pains and certain other bodily sensations to provide such counterexamples.  For example, it is sometimes claimed that a sensation of pain is mental but lacks any intentionality.  Pain is (so the argument goes) just a raw feel that isn’t “about” anything. 

That is controversial -- others (such as Tim Crane) argue that an experience of pain is directed toward the body part in which the pain is felt, and thus does have intentionality -- but Brentano’s criterion faces a more serious problem.  Some contemporary philosophers have argued that purely physical and non-mental phenomena do possess a kind of intentionality.  For example, in his book Powers: A Study in Metaphysics, George Molnar holds that there are four aspects to intentionality -- directedness; the possibility that the object of the intentional state may not actually exist; indeterminacy; and referential opacity -- and he argues that causal powers possess features like all four of these. 

Now, I think Molnar is only half-right here, and in particular that powers only plausibly possess the first two of these.  (See pp. 100-105 of Scholastic Metaphysics for discussion of Molnar’s views and related contemporary arguments.)  But they do indeed possess something like the “directedness” so emphasized by Brentano.  In particular, they possess what Aristotelian and Scholastic philosophers would call finality of a very rudimentary sort (namely the “stripped-down core notion” of final causality or teleology that I referred to in a recent post). 

Of course, most modern philosophers since the time of Descartes would reject the claim that there is anything like Aristotelian finality in the material world.  They would relegate all “directedness toward” an object to the mind, and would say that where it appears to exist in nature, that is only because the mind projects it onto nature, rather than finding it in nature.  (Molnar and like-minded contemporary thinkers are really neo-Aristotelians of a sort, whether they realize it or not.)  Hence if one accepts the modern, post-Cartesian conception of matter as devoid of any inherent finality, teleology, or directedness, and regards all finality, teleology, or directedness as mind-dependent, then one will be hard-pressed to resist Brentano’s criterion -- which is precisely why so many contemporary philosophers have found it plausible.  (It is ironic, given Brentano’s criticism of what he takes to be the Cartesian criterion, that the plausibility of his own proposed criterion itself presupposes a post-Cartesian conception of matter.)

It should also be noted that that is not all Brentano had to say on the subject, though.  He also characterizes the mental as that which we know via a kind of “inner perception.”  Is this a better criterion of what sets the mental apart from the non-mental?

I would answer: It is hard to say, in part because the term “mental” is used so broadly in contemporary philosophy.  Suppose we use the term “mental” narrowly, to refer to what is true of the intellect specifically.  In that case, neither of Brentano’s criteria is quite right, at least from the point of view of the Aristotelian or the Thomist.  The first criterion is not quite right because non-human animals, plants, and indeed inorganic phenomena can all exhibit a kind of “directedness” and yet lack intellects.  The second criterion is inadequate if we suppose that anything that is conscious has at least some kind of “inner perception” (though whether this is the case will depend on how we interpret the notion of inner perception).  For animals are conscious and yet lack intellects.

From an Aristotelian or Thomist point of view, it is not intentionality as such that is the mark of intellectual activity, but rather intentionality that involves the conceptualization of that toward which the mind is directed.  Animal consciousness has a kind of intentionality, but not the grasp or application of true concepts.  Hence conceptual thought is the mark of the mental, if by “mental” we mean strictly intellectual activity. 

If we use “mental” more broadly, though, to include any conscious phenomena -- including the kind of conscious experiences had by non-human animals, which lack intellects -- then perhaps Brentano’s second criterion (“inner perception”) is defensible.  (In this case, though, the criterion would not support any claim to the effect that the mental, broadly construed, is incorporeal or non-bodily -- at least not for Aristotelians and Thomists, who regard the intellect as incorporeal, but sensory experience as corporeal or bodily.)