Most moral philosophers consider only physical actions, speech and thoughts that may have an impact on others as within the scope of morality, while many religion believers who suppose the omniscience of deity (deities) think that there are ‘immoral thoughts’, even though they are not expressed or manifested. For example, the Buddhists sometimes mention ‘bodily, verbal and mental karma’(trīni-karmāni in Sanskrit). Are our private thoughts regulated by morality? Or, should they be? Is there any literature on this issue?
Great question. We have some intuition for the possibility of at least some thoughts to be subject to morality, for instance, beliefs based on prejudice. However, many thoughts of ours are involuntary (for this reason, many thoughts are not actions), and people (at least in the Kantian tradition) tend to think that we are only morally responsible for what is within our control. Secondly, one could argue that thoughts themselves are private in the sense that they do not directly affect others, and so no one should point fingers at us for what we think (though this is not exactly the same as saying that our thoughts are not subject to morality).
Here’s some literature (in the analytic tradition) that might interest you. Generally, the topic you want to look up is the Ethics of Belief.
For an overview, check out this SEP entry on EoB.
Other interesting reads:
- W. Clifford (1876). The ethics of belief.
- R. Basu (2019). The wrongs of racist beliefs.
- P. Hieronymi (2008). Responsibility for believing.
I’m also interested to learn what other traditions make of this question, particularly East Asian / Buddhist ones!