How can it be that a thing has a meaning and that the fact that it has this meaning can explain certain effects or is at least relevant for the explanation of these effects? This question is the central theme in Fred Dretske’s book Explaining Behavior. Here, I don’t want to discuss this interesting philosophical work, but only one of its theses, namely that talking about reasons makes only sense, if reasons are causally relevant for the actions they are reasons for. Is it true?
When asking the leading question of his book, Dretske had two things in mind. First, the meaning concerned as such must be relevant for the explanation of the effects. “A soprano’s upper-register supplications may shatter glass, but their meaning is irrelevant to their having this effect” (1988:79). Even if the sounds had no meaning, the effect would be the same. However, there are cases where the meaning of a thing is explanatorily relevant, and it is these cases that Dretske’s theory of the causal role of meaning refers to (1988:77-80). Second, explanatory relevance is for Dretske causal relevance. As he puts it in his “Reasons and Causes”: “Any theory of meaning that doesn’t make a thing’s having meaning into a causally relevant property of the thing (and hence the fact that it has meaning into an explanatorily important fact about the thing) is a theory of meaning that can be rejected at the outset.” (1989:5).
When Dretske talks about the causal relevance of reasons, apparently he implied: 1) If reasons are not causally relevant for behaviour, they are also not relevant in a different way. For if reasons are not causally relevant, although they are otherwise relevant, we might suppose that Dretske would at least attach some value to having them in that case, and he would not reject a theory that ignores or rejects their causal relevance at the outset. 2) If we talk about the reasons why we do something, this “why” has a causal meaning.
For Dretske, reasons are “those content-possessing mental states (belief, desire, fear, regret) we invoke to explain one another’s behavior” (1988:79). Particularly, the agent’s reasons are the cognitive factors and conative conditions that steer his behaviour. The function of the cognitive factors C or “beliefs” is “.… to indicate the presence of those conditions that, if the right motivational state is present, will lead, other things being equal, to M” (1988:105) with M being what is done by the agent. However, having a belief is not sufficient for M taking place. There must also be a conative condition or “desire”, i.e. a certain motivational state (D). Basically, the cognitive factors and the conative conditions determine together the agent’s behaviour, and so they are the reasons for this behaviour (1988:105-107).
Take now this case: A friend of mine calls me asking whether I can come to help him. So, I take my coat, walk to the shed, and take my bike. Seeing that I want to go, my wife asks me to post a letter.
What I do now can be described as 1) posting my wife’s letter; 2) going to my friend. Take 1). If we apply Dretske’s theory, the cognitive factor is my belief that my wife wants me to post a letter. I want to do her a favour, and so I have a desire (conative condition) for really doing it. This analysis seems to explain my action “posting the letter” (M). However, we must also consider my “second” action: going to my friend. It can be explained in the same way as the “first” one, but that is not what matters here. I want to examine the relation between both actions. If I had not gone to my friend, my wife would not have asked her question, and I would not have posted the letter, but she would have done it herself. So I post the letter because I go to my friend. My going to my friend is therefore a relevant explanatory factor of my action “posting my wife’s letter”. Accordingly, it is a reason as described by Dretske, namely a “belief”. But is it also a causal relevant explanatory, namely a cognitive, factor for my action “posting the letter”? Dretske correctly says that cognitive factors can be causally effective only if there is an accompanying conative condition, or “the right motivational state” (see above). As just said, the conative condition (desire) in my example is that I want to do my wife a favour. However, the consideration that I am to go to my friend does neither refer to a circumstance that can fulfil my wanting to do my wife a favour, nor is it a cognitive factor that is or can be fulfilled by this conative condition. As Dretske puts it, it is not an “internal indication of the appropriate stimulus conditions” (1988:113n). In order to fulfil this conative condition, we need another cognitive factor that does indicate the appropriate circumstances, in this case that my wife asks me to post the letter. I go to my friend because he called me and because I want to do him a favour. It is not my going to my friend but my wife’s request that is the causally effective reason for my action of posting the letter; at least in the sense of “reason” given by Dretske. However, in the presence of another cognitive factor, my going to my friend becomes a relevant reason for doing my wife a favour and this is what happens in my example. So, in this case there is a (cognitive) factor that is a relevant reason for an action but not a causally relevant reason in Dretske’s sense.
The upshot is that reasons can be relevant for explaining of what I do without being causally relevant for it. Nevertheless, reasons give an answer to the question why I act that way.
Dretske, Fred, Explaining Behavior. Cambridge, Mass. etc.: MIT; 1988Dretske, Fred, “Reasons and Causes”, in Philosophy Perspectives, vol.3 (1989), pp. 1-15