Here is what Harris has to say about the relation between injustice, brain states, and consequences:
The only thing wrong with injustice is that it is, on some level, actually bad for people. Injustice makes its victims demonstrably less happy, and it could be easily argued that it tends to make its perpetrators less happy than they would be if they cared about the well-being of others. Injustice also destroys trust, making it difficult for strangers to cooperate. Of course, here we are talking about the nature of conscious experience, and so we are, of necessity, talking about processes at work in the brains of human beings.
This seems right for the most part, but it is not clear why “conscious experience” reflected in human brain states is necessary to account for the wrongness of injustice. Consider a variation to Gilbert Harman’s “Room 306” thought experiment:
You have five patients in the hospital that are dying, each in need of a separate organ. One needs a kidney, another a lung, a third a heart, and so forth. You can save all five if you take a single healthy person and remove his heart, lungs, kidneys, and so forth, to distribute to these five patients. Just such a healthy person is in room 306. The patient in 306 has been in a coma for five years and shows no signs of coming out of it. Being familiar with his test results, you realize that he has the right tissue compatibility with those waiting for organ donors, something that has been problematic for each of them getting a transplant. If you do nothing, the patient in 306 will persist in his comatose state for an indefinite amount of time while those in need of transplants will surely die in the very near future. The other five patients can be saved only if the patient in 306 is cut up and his organs distributed. In that case, there would be one dead and five saved.
If the Dr. carried out these actions, there would be a clear instance of injustice. Yet the comatose patient has no conscious experience of the violation of his person (which is ultimately relevant). If the Dr. acted in secret and successfully covered his tracks, then he alone would be the only agent to have a conscious experience of his actions. Yet he senses no injustice, because his actions benefited the many over the one. Certainly, it is possible for him to come to regret his actions later, but it is highly implausible to suppose that at this later time injustice would then supervene.
As far as I can tell, this is a major problem for Harris’s brand of ethical naturalism. Locating moral properties in the natural properties of human brain states is insufficient to determine the nature of justice. Justice is not posterior to brain states—it imposes its constraints prior to them. Thus, Harris’s view seems far too restrictive to account for injustice.