If moral values are a part of the real world, then they must be a part of the explanation of things.
When we ask why something happened (or did not happen), a part of the explanation, at some level, must be "because it was my duty" or "because it was wrong."
It is not sufficient to say, "because I believed it was my duty" or "because I thought it would be wrong." A person can refuse to leave his house because, "I believe there is a dragon outside that will eat me," without it being the case that there is a dragon outside that will eat him. Similarly, a person can do something "because I believe it was my duty" without there being an actual duty.
So, we must establish the existence of a moral ought that is independent of belief that there is a moral ought.
Peter Railton, in arguing for moral realism, recognizes that he must establish moral values as a part of the causes of things.
Where is the place in explanation for facts about what ought to be the case-don't facts about the way things are do all the explaining there is to be done? ("Moral Realism", The Philosophical Review, Vol. 95, No. 2 (Apr., 1986), pp 163-207.)Here, we come to the gap between what is, and what ought to be.
There are two ways to handle this gap.
One way is to argue that "ought" represents something distinct and separate from "is" - a separate kind of thing which nonetheless has the capacity to interact with things in the real world and alter the motion of physical things.
Questions about the nature of this "different kind of thing" and, in particular, about how it interacts with physical matter in ways that cause physical objects to move in particular way without ever being discovered by physicists, are enough to argue for setting this aside as an option of last resort.
Yet, it is interesting to note that many materialist fail to recognize the significance of this.
While claiming to be materialists, they also immediately respond to any attempts to reduce morality to a set of material properties by asserting an is/ought distinction as if it was established law. Yet, if materialism is true, then either moral claims must be reduced to claims about what is, or they do not exist at all and we should quit talking about them.
SHOULD quit talking about them. That phrase hints at how difficult it would be to eliminate normative language.
So, we are left with the option of accounting for "ought" within the realm of what "is". The question is not, "Can 'ought' be derived from 'is'?" - a question that those who insist that there exists an is/ought gap answer with a dogmatic "no". The question - at least for the materialist - must be, "Given that 'ought' - if it is at all real - must be a type of 'is', what type is it?"
When it comes to the objection of denying that 'ought' (or 'should') does not exist at all, I would simply like to challenge an individual who likes this route to try to eliminate normative terms from his language.
Railton recognized this challenge, and answers his own question, "Don't facts about the way things are do all the explaining there is to be done?" by saying:
Of course they do. But then, my naturalistic moral realism commits me to the view that facts about what ought to be the case are facts of a special kind about the way things are.In other words, "ought" is not something distinct and separate from "is". If it was, then it wouldn't exist at all. "Ought" is a subset of "is". In the huge room filled with what "is", there is a shelf in back labeled "oughts" - a part of, and not separate from, what is.
In Part 4 of this series, I described how Railton sought to establish the "is" of non-moral value (non-moral goodness). He pointed out that the "goodness" of drinking water or clear soda explains how a person can come to have a liking for it - can come to value drinking it when travelling for its own sake. It's "goodness" is reduced to its capacity to fill certain desires. In this case, it is found in the capacity that drinking water or clear soda has to alleviate the symptoms of dehydration, to which our hypothetical agent has an aversion.
In Railton's story, the agent's acquired preference for clear soda over milk when traveling also becomes a part of "what is" - explained, in part, by the goodness of drinking water and the badness of drinking milk. Among other things, this new acquired preference explains changes in the agent's behavior - a set of real-world events.
Being such as to fulfill the desires in question is a real-world property. It exists. This real-world property is also called the property of non-moral goodness. It identifies things that the agent has reason to realize - that the agent ought to make real in the practical non-moral sense of the word "ought".
I would like to repeat the point that this "ought" exists independent of whether the agent believes or wants it to be the case.
It does not exist independent of the agent's desires. In fact, it depends for its existence on (1) the agent's aversion to the symptoms of dehydration, and (2) the power of drinking water or clear soda to eliminate those symptoms. However, the aversion exists - it is a part of the real, material world. The power that drinking water or clear soda has to alleviate those symptoms exists - it is a part of the real world. Consequently, the ought exists - it is also a part of the real world,
Non-moral (practical, instrumental) oughts are real. However, their reality does not imply that moral oughts are real. Yet, they do point us in a particular direction where we can start looking for real moral oughts. If moral oughts are a species of practical, instrumental oughts, then they too might be real.