▻ INTELLECTUAL SETTING
This is a question and a debate that goes back to the 1950s. A.I. Melden and R.S. Peters were key figures. Most philosophers now would accept, following Donald Davidson, that reasons are causes but Melden and Peters thought there were logical differences - conceptual and not just dictionary differences - between reasons and causes.
▻ ARGUMENT FOR THE DISTINCTION BETWEEN REASONS AND CAUSES
Elizabeth Anscombe provides an example on which we can work :
A man moves his arm, thereby operating the pump, thereby replenishing the water supply, and thereby poisoning the household. How many actions have been
performed here? Anscombe answers: " moving his arm up and down ... is, in these circumstances, operating the pump ... and, in these circumstances, it is poisoning the household" (p. 188). Margolis takes this as his point of departure and argues in the following way. We are granting that the action of operating the pump is identical with the action of poisoning the household. Let us suppose
that the agent's operating the pump was intentional, i.e. his intention to operate the pump was part of his reason for operating the pump. It can hardly be supposed that the agent's intention to operate the pump was any part of his reason for poisoning the household since, ex hypothesi, the relevant intention was not had by the agent. Therefore having the intention of operating the pump reason explains operating the pump but does not reason-explain poisoning the household. ( L. F. Mucciolo, 'Explanation by Reasons and by Causes Again', Mind, New Series, Vol. 82, No. 328 (Oct., 1973), p. 604.)*
The agent has a reason for operating the pump, i.e. to replenish the water supply. No more than that. He has no intention of poisoning the household and poisoning the household was not his reason for operating the pump. Yet his action causes the household to be poisoned. In this case reason and cause are not identical.
▻ CRITIQUE (1)
Yet this doesn't show that reasons cannot be causes and are not causes. The agent's desire to replenish the water supply was his reason to operate the pump; and that desire - that reason - caused him to operate the pump.
All that the example Mucciolo presents does is to show, what no-one will dispute, that an action can have unintended consequences - that one's reasons can cause actions that produce consequences that one didn't intend and that did not inform one's reason for acting.
▻ CRITIQUE (2)
Suppose my room is cluttered to the point where I cannot effectively work in it.
I believe I can sort out the chaos and want to do so. My belief and want motivate me; I intend to tidy room. My reason for tidying is that I want to work effectively in the room.
I set to, put books in order, tidy papers, throw out old bills and receipts. In a short while the room is tidy.
We can say that my wanting to work effectively in the room is, or was, my reason for tidying it. This is a perfectly sound reason-based explanation.
But it also fits all the conditions for a causal explanation. In a causal explanation (to keep to a simple case) :
The cause is an event or happening
The cause precedes the effect (occurs before it)
If the cause had not occurred, the effect would not have occurred either.
The reason-based explanation translates straight across :
My reason for tidying was that I wanted to work effectively in the room.
The want occurred - onset - at a time. I did not have it at time t in my lazy
days; I did have it at time t1, my moment of resolve; and I did not have it at
time t2 when the tidying had been done. It was an event or happening.
The reason preceded the tidying
If the reason had not occurred (my wanting to work effectively in the room), the effect would not have occurred either (the room would not have been tidied.
So the reason-based explanation is a causal explanation
A. I. Melden, 'Free Action' (London, 1961), p. 184.
R. S. Peters, The Concept of Motivation (London, 1958), p. 12.
W. D. Gean, 'Reasons and Causes', The Review of Metaphysics, Vol. 19, No. 4
(Jun., 1966), pp. 667-688.
D. Davidson, 'Actions, Reasons, and Causes', Journal of Philosophy, 60 (1963),
pp. 685-700. Reprinted in 'Essays on Actions and Events', Oxford: Clarendon
Press, 2nd edn, 2001.
Fred Dretske, 'Reasons and Causes', Philosophical Perspectives, Vol. 3,
Philosophy of Mind and Action Theory (1989), pp. 1-15. Published by:
Ridgeview Publishing Company.
E. Anscombe, 'Intention' (Oxford, 1957)
- Mucciolo uses this example but he does not support the reasons/ causes distinction.