In a comment to Can Mere Thoughts be Morally Wrong? I wrote:
There is nothing wrong with the mere occurrence of a thought, any thought, even the thought of killing someone just to get his wallet. For the thought might arise without my willing it to arise. My point is that once it has arisen, once it is present to my mind, it becomes a legitimate object of moral evaluation, whether or not that particular thought is followed by a corresponding action.
Peter Lupu responded:
Unless I misunderstand what he intends to say here, Bill appears to endorse thesis (A); i.e., that even a single mere-thought with a certain content is “a legitimate object of moral evaluation” and the verdict of immorality. Notice that moral scrutiny applies to the thought, not the person (I suppose because, under the conditions specified, the person is shielded by the principle “ought implies can”).
I can see that I haven't stated my thesis clearly enough. We need to make some distinctions.
1. Arisal versus Harboring. Thoughts arise or emerge or occur. The thoughts under discussion are thoughts of actions which we agree are morally wrong, e.g., the thought of setting a dog on fire. My claim is not that the arisal of such a thought is wrong, but that its harboring is wrong, though of course not as wrong as doing the corresponding deed. The arisal is not under the direct control of my will, whereas the harboring is. (Whether 'evil' thoughts are under the indirect control of the will I leave for another occasion.) Once the thought is fully present in my mind, i.e., once it has arisen and I am aware of it, I am free to allow it to stay there (in which case I harbor it) or else dismiss it. If I harbor it, I can go on to elaborate it, embellish it, deliberate on how to implement it, etc. It is obvious that each of us normal humans has some control over his mental contents once they have arisen, whether or not we have any control over their arisal. We are free to harbor or dismiss at least some of the thoughts that occur to us. So, contrary to what Peter may be suggesting, it is not the arisal of the thought, but its harboring/dismissal, that I am claiming is morally evaluable. In particular, I am claiming that some thoughts are such that their harboring is morally impermissible, while some other thoughts are such that the harboring is morally permissible. Still other thoughts are morally neutral or indifferent.
2. What is a thought? In a thought one must distinguish act and object, the thinking and the object to which the thinking is directed. The object-directedness of a thinking is its intentionality. The thinking is a state of a subject, a person. The object need not be a state of a person and typically isn't. And the object of a thinking need not exist or obtain. The act of thinking is a temporally qualified particular with a certain duration even if it lasts only a split second. A particular is a nonrepeatable item. As a particular, a thinking is a token of a type. The type might be: imagination. Or it might be a non-imaginative conceiving. For example, the thought occurs to Tom that he can poison his neighbor's dog to get him to stop barking. When the though first arises, it is a pure conceiving with no associated imagery, but then the thought transmogrifies into one that is an imagining of poisoning the dog.
3. Mental Acts and Mental Actions. I claim that there are three classes of actions: overt physical actions (e.g., dousing a dog with gasoline), speech-actions (more commonly known as speech-acts) such as threatening verbally to douse a dog with gasoline, and mental actions, e.g., the harboring, maintaining, elaborating, embellishing, etc. of the thought of dousing a dog with gasoline and setting the critter on fire. These mental actions, as doings, are under the direct control of the will and are therefore not removed from the purview of moral evaluation by the Ought imples Can principle, which both Peter and I accept. But I am not claiming that mental ACTS are so subject. For example, the mere occurrence of the thought when it first arises is a mental act, i.e., a conscious intentional state. The same goes for the noting, in reflection, of the presence in my mind of the thought. That is not a doing, but a mere noting. I simply note that the thought is present to my awareness. The harboring, maintaining, elaborating, etc of the initial thought in a series of further thoughts involves mental doings.
An action is something one can decide to do or leave undone. If so, then it seems clear that there are mental actions, e.g., deliberating how to kill the neighbor's dog. Hearing the dog bark, on the other hand, is not a mental action but a mental act: it is an occurrent episode of intentional awareness. One does not decide to hear or not hear the barking of a dog. Wilfrid Sellars is good on the distinction between mental acts and mental actions. See Science and Metaphysics: Variations on Kantian Themes, Routledge 1968, p. 74.
4. My Thesis, then, is that some thoughts which are mental actions are subject to moral evaluation. Thus the thoughts involved in deliberating how most effectively to seduce my neighbor's wife or kill his dog are mental actions, and are, as such, under the control of the will and morally evaluable as either morally acceptable or the opposite. If Peter is denying this, then he is saying that NO thoughts which are mental actions are subject to moral evaluation as either morally acceptable or the opposite, which is equivalent to saying that ALL thoughts are morally neutral or indifferent. Would not Peter need to argue for such a sweeping assertion?
I won't now repeat or refine my arguments for my main thesis. My present purpose is merely to state the thesis clearly. Peter can tell me whether he thinks it is now clear enough to evaluate.