Jason Bridges

University of Chicago


Phil 31410, A03—lecture 6 notes

Can reasons explanations be both causal and justificatory?

(Davidson, “Mental Events”)


I. Recap

Davidson endorses this conjunction of views:

Causalism + Weak normativity thesis: When one explains an agent’s action by giving the reasons for which she performed it, one both gives a causal explanation of the action and justifies it.


Recall it is a subjective sense of justification at work here: justifying in this sense is a matter of what the agent took to justify the action, whether or not she was right about this.

Recall that Davidson weakens the sense further by maintaining that an action’s seeming justified to the agent is just a matter of the action’s satisfying a “pro attitude” on the part of the agent, a category Davidson construes to include impulses, drives, yens and so forth.


Note that this imposes two necessary conditions on reasons explanations.  It doesn’t imply that meeting these two conditions is all that is involved in explaining an action by giving the agent’s reasons for it.  And indeed, Davidson argues that we can meet these two conditions but not succeed in giving the reasons for which an agent acted.

The example of the rock climber (in “Freedom to Act”) makes this point.


Davidson doesn’t think you can spell out sufficient conditions for giving a person’s reasons for an action without just helping oneself to talk of a person’s reasons for an action.  The idea of a reason for which an action is performed cannot be reduced or naturalized, in Davidson’s view.  We shall return to this issue.


We noted last time that there is no logical inconsistency in asserting both of these conditions as necessary.  Nonetheless, as Davidson notes in “Actions, Reasons and Causes”, one might doubt that they cohere.  One might doubt that there can be a kind of explanation that both causally explains and justifies.  One might think that causal relationships and justificatory relationships obtain in mutually exclusive spheres.


We can regard “Mental Events” as a response to a challenge of this nature.  But it will take some stage-setting to bring the challenge into view, let alone the response.


II. The nomological character of causality

There is a longstanding view, which Davidson traces to Hume, that the ideas of causation and law are essentially linked.  In particular, one might think that whenever two events are related as cause and effect, there being so related is an instance of a perfectly general law of nature.  Wherever there are causal relations, there are natural laws governing those relations.


This Davidson calls this the nomological character of causality.  “Nomological” means of or relating to laws.


The nomological character of causality: When one event is a cause of another, there is a strict causal law under which the pair falls.


I’ll say a word on “strict” in a moment.


But here’s the basic idea.  Suppose an F-event causes a G-event.  Then the simplest possibility (crucially, as we’ll see, not the only possibility) the nomological thesis envisions is that it’s a law that all F’s cause G’s.  So suppose a bolt of lightning causes a thunder clap.  Then the simplest possibility that would accord with the principle is that it’s a law of nature that all bolts of lightening cause thunder claps.


Why might one buy this principle, and why does Davidson?  This is a difficult question that we can’t get into here.  Hume’s reason for believing something like the principle appears to be something like the following train of thought: since instances of the causal relation aren’t directly perceived, aren’t found in our experience (or so Hume assumed), the only thing left for the causal relation to be, such that we would be in a position to know of instances of it, is a relation whose instances are tied to the existence of repeating patterns of events.  And it is the existence of repeating patterns of events that laws of nature assert.

I don’t think, given Davidson’s views about perception, that this can be his reason for his own support for the thesis, but here at least, he gives no other.  (“Law and Cause” discusses the issue, but it is a disappointing article.)

Many contemporary philosophers are with Davidson on this.  Their support probably has to do with the conviction that the thesis accords with a naturalistic view of the world

However, what matters for our purposes is where Davidson ends up, regardless of the merits of the reasons that got him there.


III. The anomalism of the mental: an illustration

Davidson endorses a second thesis:

Anomalism of the mental: There are no strict psychological laws.


A psychological law is a law that is stated using mentalistic vocabulary.  The precise boundaries of mentalistic vocabulary are debatable, but it includes at least the vocabulary of propositional attitudes—“belief”, “desire”, and so forth.


So a psychological law would be one, for example, that linked having a certain desire and belief with performing a certain action.


Here’s a putative such law from another article of Davidson’s: (“Philosophy as Psychology”, p.233.)  A person who desires to eat an acorn omelet will do so if opportunity exists and no other desire overrides.


Let’s look at this example a bit more closely.  Consider first a simpler version:


It’s a law that anyone who desires to eat an acorn omelet will do so.


This is obviously false.  I might have a desire right now to eat one, but the ingredients for one are not to be found, so I can’t.  Nor is it a law that anyone who desires to eat an acorn omelet and has the ingredients to do so will follow through.  There are all kinds of reasons why one might not.  I don’t have the time.  I screw up the cooking and have to throw it out.  I decide it would be best not to eat something likely to lead to indigestion, however much I hanker for it.  Nor, of course, is it a law that anyone who wants to eat an acorn omelet, who has the means, time and requisite culinary competence, and who doesn’t think it will lead to indigestion will eat an acorn omelet.  Maybe my religion forbids omelets.  And so on.


What about the more complex formulation that Davidson considers?  Is it a law?

Davidson’s answer to this question is that it is not.  It might be interpreted so as to be a true generalization, but if so interpreted, it is not a law of nature but a vacuous quasi-logical truth.

For given what we have seen to be the limitless possibilities for defeating circumstances, it would seem that the statement will be a true generalization only if “no other desire overrides the desire to eat an acorn omelet” means that the desire to eat the acorn omelet wins out among competing desires, where that is to say that it is the desire that is actually acted upon.

A similar point can be made about the “opportunity exists” condition.

So interpreted, the generalization is (nearly) vacuous.  It’s like saying that objects fall at such and such a rate in the cases where they fall at such and such a rate.  A person will eat an acorn omelet if his desires and opportunities are such that he will eat an acorn omelet.


Part of what Davidson has in mind when he speaks of a strict law is that the law must either hold in every case or the conditions under which it holds must be specifiable non-circularly.  His point is that this does not appear to be the case with our putative law.  For there’s obviously an endless number of conditions whose obtaining might prevent someone who desires an acorn omelet from eating one.  There seems no way to spell out the conditions “if the opportunity exists and no desire overrides” so as to make the claim exceptionless unless we gloss as saying that desires and opportunities are such that someone who desires an acorn omelet will eat one.


(This is not all Davidson means by talk of strictness.  There are complicated questions of interpretation here which for our purposes we can fortunately ignore.)


So let’s grant that the sample psychological generalization fails to be a strict law.  But how do we know that there are never such laws—in particular, as this is the case that interests us, no laws linking desires and beliefs (and other propositional attitudes) with actions?


Davidson takes himself to have a general argument to this effect, much of it contained in the dense passage at the end of “Mental Events” (pp. 222-223).


IV. The anomalism of the mental: an argument

Davidson’s development of the argument strikes me as a bit confused and misleading.  I’m going to present a somewhat different argument, in the spirit of some of what Davidson says, that’s simpler than Davidson’s actual argument.  On the other hand, it cannot be construed as anywhere near as decisive as Davidson appears to regard his argument.


The basic idea of the argument is that there is a fundamental contrast between explanations in the natural sciences—physics, chemistry and the rest—and reasons explanations.


1. In a natural-scientific explanation, a phenomenon is explained by showing how it is an instance of how things tend to happen.


To put it another way, these explanations work by subsuming phenomena under natural laws.  Statements of natural law are claims about how things must in general happen in our universe.  What we do in a natural science is to show how the phenomenon in question, say of one thing’s causing another, falls under a certain natural law, and so is an instance of the universe’s working in the way that it tends to work.


Generality is involved in these explanations in more than one way.  The very idea of a law of nature brings with it a generality that offers an explanatory punch.  Thus it is explanatory for a child to be told, if she asks why her salt dissolved when she put it in her water, that it is a law that salt dissolves when put in water.  This does tell her something of explanatory significance: namely, that this occurrence was no anomaly, but an instance of how things generally happen.


But secondly, such an explanation is more illuminating to the extent that it subsumes the phenomenon under laws that are stated in more and more general terms.  Thus it’s one thing to point to the law that salt dissolves in water.  It’s another to state a more general chemical law, holding of an array of solutes of which sugar is just one, and an array of solvents of which water is just one.  And it is a further advance to state the still more general chemical laws that govern each stage of the process.

But in every case the key element is that of representing an occurrence or circumstance as an instance of how things happen as a matter of natural law, of how the universe works in general.


2. In a reasons explanation, an action is explained by showing how in performing that action, the agent approximated to the ideal of rationality.


This claim can be seen as underlying the (weak) normativity thesis.

The weak normativity thesis holds is that in giving a person’s reasons for doing something, we must show, so far is possible, why the action made sense to her—why it seemed worthwhile.  The reasons for which a person acts must be seen to be reasons that justify the action.


Why?  Well, insofar as this condition is not met, we cannot see the person as rational. Rationality is a matter of doing what it makes sense for one to do (and believing what it makes sense for one to believe).  An ideally rational person always does what it makes the most sense for her to do (and always believes what it makes the most sense for her to believe).


(Thinking this idea through points us toward at least some forms of holism about the mind.  For an ideally rational person must be one whose whole body of propositional attitudes and actions rationally cohere over time—that is, make sense of each other.  More on this in a moment.)


Reasons explanations needn’t assume that anyone actually fully achieves this ideal.  The claim is rather that, if we do want to explain a person’s actions in terms of her beliefs and desires, then we do have to see them as at least approaching that ideal.  The transitions from reasons to actions must be to some degree rational.  It must to some degree make sense that this was the person’s reasons for that.


But the question still remains: why must reasons explanations portray agents as even approximately rational?

Consider an example   If you were to bother to think about why your classmates have walked into this room and sat down, you would assume it was because they wanted to participate in this class, or at least felt obliged to, and believed that sitting in this room at this time was the way to participate.

This explanation works by making your classmates’ actions intelligible in a very particular way—namely, by showing how the action might have seemed to you the thing to do, were you in their shoes.  (As, in fact, you are.)  We ought to be very hesitant to claim, say, that someone came in and sat down because he didn’t want to participate in this class.  Barring further clarification, this ‘explanation’ makes the action unintelligible (by our lights, of course). It presents the action as senseless or pointless.  But then it is not an explanation of the action at all.

(We find all but the craziest people rational in all the little things.)


This is the point Davidson makes in a passage in different article (read p. 237).  All explanations in rational psychology, all appeals to beliefs and desires to explain actions, no matter how trivial or how significant, rest on the supposition he here describes.


We will return to the idea of rationality and its relationship to justification at some length later in the course.


But for now, the point is that the contrast we have drawn between the two styles of explanation might be seen as licensing the anomalism thesis.  For the contrast shows that the two kinds of explanation are wholly different creatures.  Showing that something approximates to an ideal of rationality is fundamentally a different matter from showing that something is an instance of how things tend to happen.  If you ask, “Is action A rational given the belief that p and the desire that q?” your question is not effectively answered if I were to say, “Well, as a matter of fact, doing A is what generally tends to happen when there’s a belief that p and a desire that q.”  You might fairly retort, “I didn’t ask whether doing A is what tends to happen in these psychological circumstances.  I asked whether doing A in those circumstances made sense.”

So, the thought might run, we have no reason to expect that any given reasons explanation of the form “X did A because X believed that p and desired that q” corresponds to a law of nature of the form that anyone who believes that p and desires that q will do A. (This inference is obviously open to question.)

Thus, anomalism of the mental.


V. The anomalism of the mental: the explicit argument of “Mental Events”

Notice that on the previous construal of the argument, the issue of strictness (which on reflection plays a very confusing role in Davidson’s discussion) is a red herring.  What matters is a difference between explanations that involve laws, however strict, and explanations that involve the ideal of rationality.


However, we can to some extent understand Davidson’s actual argument—which argues that the existence of strict psychological laws is incompatible with holism—as a corollary of the line of thought just sketched.


First, holism.  People, except those in very desperate or confined circumstances, are concerned at any given time with the satisfaction of a great many desires and with carrying through many ongoing projects and plans.  And we all have many, many beliefs about the world around us potentially relevant to the satisfaction of our desires and projects.

Thus whether a person’s doing something on a particular occasion makes the most sense out of the options can turn on many complex, interacting considerations—not just one desire and one belief taken in isolation.

A given reasons explanation cannot hope to enumerate all of these considerations.  But, if our aim in offering reasons explanations is to show a person in her actions to approximate to the ideal of rationality, we must acknowledge the holism in other ways.

We do so by our awareness that any reasons explanation of an action that we offer is always revisable in light of new information about what the person wants or intends or believes.

And we do so by our tacitly understanding a reasons explanation not as self-standing, but as one piece in a much larger (and, of course, largely hypothetical) explanation of the agent’s thought and activity over time.


But if our practice of offering and revising reasons explanations must have these features, then, says Davidson, we cannot expect strict laws linking reasons with actions to be forthcoming.


Read passage on pp. 222-223.

Clearly there is much going on in this passage.  I suggest there is at least this:

If there are laws linking beliefs and desires with actions, then there are laws linking beliefs and desires with physical events, bodily movements in particular, hence with the neurophysiological events involved in such motions.

But if there were such laws, they would prevent reasons explanations from having the character that they must have if they are to do what it is their point to do.  There wouldn’t be the “slack” that there must be to allow for the ongoing construction and revision of a “theory” of a person’s overall psychology and ongoing activity.  But if we can’t have that, we can’t understand the agent as rational.


There’s much more that could be said about this.  But let’s move on to the challenge I mentioned at the beginning.


VI. The challenge and the monist solution

The challenge to Davidson’s view of reasons explanations as both causal and justificatory can now be stated.  The challenge is that the conjunction of the nomologicality thesis and the anomalism thesis conflicts with causalism.

Here’s the argument:


1.     When one event causes another, there is a strict law under which they fall. (nomological character of causality)

2.     There are no strict psychological laws. (anomalism of the mental)


We’ve noted that there might be ground for a stronger version of 2, which leaves out the word “strict”.  We then would need only a weaker version of 1.


3.     Therefore, a person’s beliefs or other propositional attitudes can’t be the causes of anything she does. (from 1 and 2)

4.     Therefore, reasons explanations aren’t causal explanations. (from 3 and Davidson’s psychologism about agential reasons)


In a nutshell: if there are no laws under which reason-action pairs fall, but if all cause-effect pairs fall under laws, then how can the reason-action relationship be a causal one?

Davidson’s solution involves application of the simple insight that events, like objects, have various properties, and thus can be variously described.


Consider this singular causal statement:

          The lightning bolt caused the thunder clap.


Davidson had the following simple thought about what such a statement does: it asserts a relation between two events, more specifically, it asserts that the one event caused the other.

Thus we are led to the following simple proposal about the form of such statements:


          A caused B,

(where “A” and “B” are replaced by either descriptions or names of two events)


(Davidson also had ingenious suggestions about the forms of other kinds of causal statements, which I’ll bypass.  Involves quantificational logic and takes us to far afield.)


Now given Davidson’s analysis, a singular causal statement is true just so long as what replaces “A” refers to or picks out an event that caused that which what replaces “B” picks out or refers to.  That means that we can replace what replaces “A” with any description that picks out the same event or with any name that refers to the same event and preserve the truth-value of the original statement.


So if the lightning bolt was the only notable thing that happened while I was in the kitchen last night, then:


The only notable thing that happened while I was in the kitchen caused the thunder clap.


You will recall that we can put characterize this feature of these statements thusly: Singular causal statements allow for the intersubstitutability of co-referring names or co-designating descriptions salva veritate.


But now we seem to have a puzzle.  For according to the nomologicality thesis, every cause/effect pair falls under a law of nature.  But it certainly doesn’t seem to be a plausible candidate for lawhood that:


It’s a law that notable things that happen while I’m in the kitchen cause thunder claps.


So how can we reconcile the truth of the singular causal statement with the nomologicality thesis?

Easily.  There relevant law subsuming the cause and effect, the law that they fall under, is rather (let’s say):

It’s a law that lightning bolts cause thunder claps.


The point here is that for an A-event paired a B-event to fall under a given law, it’s not necessary that the descriptions “A” and “B” figure in the statement of the law.  What’s necessary is only that there is some way of describing the two events such that those descriptions figure in the statement of the law.


For a cause/effect pair to fall under a law, it suffices that there be some pair of descriptions “_____” and “_ _ _” such that “____” is true of the cause, “_ _ _” is true of the effect, and “It’s a law that _____’s cause _ _ _” is true.


What’s not required is that every way of describing the relevant events correspond to a true statement of law.

The example and its analysis shows, by the way, that statements of law are intensional, in the sense we discussed a few lectures back.


The solution to our problem should now be clear.  Suppose:


          My reason for going to the fridge was my desire to drink a beer.


Causalism is respected if:


          My desire to drink a beer caused my going to the fridge.


The nomologicality thesis is respected if:


          It’s a law that desires to drink beer cause goings to the fridge.


But according to the anomalism thesis, there can be no such law.


However, the nomologicality thesis is also respected if:


          My desire to drink beer is a C, and my going to the fridge is an E, and:

          It’s a law that C’s cause E’s.


What might substitute for “C” and “E” here?  Davidson doesn’t know.  But he thinks we can be confident that there are such descriptions available so long as we accept:


Event monism: All mental events are physical events.


Perhaps one’s desire has a neurophysiological description, for example.  Then there might be some law linking that kind of event with the kind of bodily movement that my going to the fridge is.


So mental events can cause physical events and these causal relations be subsumed by laws even if there are no laws stateable in mentalistic terms.  For each of the mental events is a physical event has well, and can thus fall under physical laws.  Just as the interesting thing that happened while I was in the kitchen last night can equally well be described as a lightning bolt, and so fall under laws that explicitly concern lightning bolts, so mental events can equally be described in neurophysiological or otherwise physical terms and so fall under physical laws.


Davidson thus rejects the inference from 1 and 2 to 3.


One worry about Davidson’s monist solution is that propositional attitudes like desires aren’t plausibly thought of as events at all, but rather as states.  Desires don’t happen or transpire, they persist.  But if so, then Davidson’s treatment of events is just irrelevant.

Davidson suggests that there are events involved: namely, onslaughts of propositional attitudes, and other changes in them.  Philosophers of mind after Davidson, by contrast, have for the most part been happy allowing states to be causes as well as events.  We’ll return to this issue next time.


Note that the solution does not require that there be a law that all desires to drink beer are neurophysiological events of type C.  Maybe my desire today to drink beer has a certain neurophysiological constitution—it’s a firing of neuron x, and my desire to drink beer tomorrow has a completely different neurophysiological constitution—it’s a firing of neuron y.

That doesn’t stand in the way of the solution.  What is needed is only that every specific case of a person’s having a desire to drink beer has some physical description or other, descriptions each of which show up in some covering law.