Sometimes ignorance is a legitimate excuse for morally wrong behavior, and sometimes it isn’t. If someone has secretly replaced my sugar with arsenic, then I’m blameless for putting arsenic in your tea. But if I put arsenic in your tea because I keep arsenic and sugar jars on the same shelf and don’t label them, then I’m blameworthy for poisoning you.
Why is my ignorance in the first case a legitimate excuse, but my ignorance in the second case isn’t? This essay explores the relationship between ignorance and blameworthiness.
1. The Blameless Ignorance Principle
The above cases suggest the Blameless Ignorance Principle:
If a person is blameless for their ignorance, then the person is blameless for acting from that ignorance.
This explains why I’m blameless for poisoning you in the first case (since my ignorance isn’t my fault), but blameworthy for it in the second case (since my ignorance is due to my carelessness).
While this principle seems sensible, why exactly does blameless ignorance excuse? And does blameless ignorance always excuse, as the principle implies? Two competing positions aim to answer these questions.
2. The Reasonable Expectation Principle
One position focuses on a person’s ability to avoid being ignorant or behaving ignorantly.
Consider an ancient Hittite lord who owns slaves, treats them poorly, and believes that his behavior isn’t wrong. Due to the widespread acceptance of slavery in his culture, it would be unreasonable to expect the slaveowner to realize that slavery is wrong. Does the slaveowner’s ignorance excuse him?
According to the Reasonable Expectation Principle:
If it is unreasonable to expect a person to avoid something (e.g., being ignorant or behaving wrongly), then the person is not blameworthy for it.
One way to understand this is that it’s reasonable to expect a person to avoid something only if the person had the ability to avoid it, given their beliefs and cultural setting. So, if the slaveowner never had an opportunity to realize that he is mistaken (e.g., by reflecting upon his own moral views, or having a conversation with someone who opposes slavery, etc.), then he is blameless for his ignorance. Therefore, it would be unreasonable to expect him not to keep slaves, given his blameless ignorance that it’s morally wrong, so he isn’t blameworthy for his slaveholding.
The Reasonable Expectation Principle also explains the arsenic cases. In the first case, since someone secretly switched my sugar for arsenic, it’s unreasonable to expect me to avoid my ignorance that I’m poisoning you: I’m blamelessly ignorant of that fact. In the second case, however, it is reasonable to expect me to avoid my ignorance: I could have avoided it by simply labeling my arsenic and sugar jars. Since I could have easily avoided that ignorance, it’s reasonable to expect me not to ignorantly put arsenic in your tea.
According to the Reasonable Expectation Principle, blameless ignorance always excuses, since it’s always unreasonable to expect someone to avoid acting wrongly if that person is blamelessly ignorant that their action is wrong.
3. The Objectionable Attitude Principle
A second position on why and when blameless ignorance excuses focuses on the morally objectionable attitudes or beliefs expressed in morally wrong behavior. According to the Objectionable Attitude Principle:
The idea here is that when I blame someone for treating me poorly, I’m responding to the morally objectionable attitudes expressed in or revealed by their behavior. Perhaps their behavior expresses a desire to harm me, a lack of concern for my well-being, or a belief that my interests aren’t important.
If this principle is true, then it doesn’t matter whether it’s reasonable to expect someone like the slaveowner to behave differently. All that matters is that his behavior expresses a morally objectionable attitude or belief: insufficient concern for his slaves’ well-being, or a belief that their interests aren’t important. This implies that even people who are blamelessly ignorant of the wrongness of their behavior can be blameworthy for it if their actions express a morally objectionable attitude or belief.
We can now distinguish two kinds of ignorance. If I put arsenic in your tea while believing it’s sugar, I’m ignorant that what I’m doing is morally wrong because I’m ignorant of the feature of my action that makes it wrong (i.e., that the white substance I put in your tea is arsenic, not sugar). This is circumstantial ignorance.
Importantly, circumstantial ignorance prevents the expression of objectionable attitudes: it’s impossible to perform an action that expresses a desire to harm (or an indifference that the action might harm) if one is blamelessly ignorant that one’s action might cause harm. Accordingly, the Objectionable Attitudes Principle implies that blameless circumstantial ignorance always excuses.
The slaveowner’s ignorance is different. He is aware of the morally relevant features of his actions (e.g., depriving people of freedom, causing suffering, etc.). But he fails to realize that these features make his behavior wrong. This is moral ignorance: ignorance of relevant moral principles or the moral relevance of various features of one’s behavior.
The slaveowner’s belief that owning slaves is not wrong, despite its harmful effects, itself involves insufficient concern for those affected, and so his behavior expresses this insufficient concern. Proponents of the Objectionable Attitude Principle maintain that, while blameless circumstantial ignorance always excuses, this is not so for blameless moral ignorance.
Our beliefs and behavior are shaped by our cultures and upbringing, which sometimes influence us for the worse. Sometimes it is reasonable to expect better of people; other times it may not be. When we cannot reasonably expect better should we not blame people for ignorant beliefs or behavior, as the Reasonable Expectation Principle implies? Or should we blame people for ignorant beliefs and wrongdoing when these express morally objectionable attitudes, as implied by the Objectionable Attitudes Principle? These questions are pertinent to potentially problematic beliefs and actions from nearly every aspect of life.
 This case and others like it are later described as morally wrong behavior. One might reasonably wonder, however, whether these are actually cases of wrongdoing, given there’s no way I could have known that my sugar had been replaced by arsenic. One might think that, if you are blameless for what you did, then you didn’t do anything wrong.
While this response is understandable, it’s worth thinking about why (blameless) actions can really be wrong. One moral theory, consequentialism, says our actions must have the best overall consequences, or else they are wrong. But poisoning someone surely isn’t the action with the best consequences, so it would be wrong on that theory. According to most moral theories, if an action actually has certain characteristics, it is wrong — for instance, if the action violates Kant’s Categorical Imperative. However, an action might have wrong-making characteristics, and yet one might reasonably believe that it doesn’t. (For instance, you might reasonably believe that feeding someone a sesame bagel will not harm them, though as it turns out, they have a sesame allergy.)
“Subjective” theories of wrongness focus on how an action is judged from someone’s “subjective” perspective, namely, whatever evidence the person has for whether a particular action meets an objective moral standard. “Objective” theories of wrongness, contrast, attempt to state an objective moral standard, independent of an individual’s evidence or beliefs. The issues of this essay arise from people doing actions that are “objectively” wrong, yet it’s arguable that people are (at least sometimes) blameless for performing those actions, because of ignorance of various types. For an introduction to two influential objective ethical theories mentioned above, see Introduction to Consequentialism by Shane Gronholz and Introduction to Deontology: Kantian Ethics by Andrew Chapman.
 This is based on a case offered by Gideon Rosen (2004).
 It is often argued that an action must be done of someone’s free will in order for that person to be morally responsible, or deserving of blame, for that action (although some deny this). Indeed, one way to understand the debate over free will is as a debate over what kind or degree of control one must exercise over one’s behavior and character in order to be morally responsible (praiseworthy or blameworthy) for these things. Thus, much of the philosophical literature on moral responsibility concerns the “control condition” on moral responsibility (see Free Will and Moral Responsibility by Chelsea Haramia, Alternate Possibilities and Moral Responsibility by Rachel Bourbaki and Free Will and Free Choice by Jonah Nagashima). Much less of this literature has been devoted to what kind or degree of awareness or knowledge is needed to be blameworthy for one’s behavior and character. This is called the “epistemic condition” (epistemology concerns knowledge and reasonable belief, so an epistemic concern is about that) on moral responsibility. The past ten or fifteen years has seen a surge of new work on this topic by a number of philosophers working on agency and responsibility. In 2017 the first edited volume on the topic was published: Responsibility: The Epistemic Condition (edited by Philip Robichaud and Jan Willem Wieland).
 This principle (or at least a restricted version of it, as will be explained later) is accepted by nearly all philosophers who write about these issues. For articulations and defenses of it, see Gideon Rosen (2003) and Michael Zimmerman (1997).
 This case is taken from Gideon Rosen. Rosen argues that the slaveowner is blameless for his ignorance and therefore blameless for his morally wrong behavior (2003, 65-66).
 In Responding to Morally Flawed Historical Philosophers and Philosophies, Victor Fabian Abundez-Guerra and Nathan Nobis address the question of whether historical philosophers should be blamed and held responsible when they had false moral views or behaved badly.
 Gideon Rosen (2004) and Neil Levy (2009) present and defend this type of view in detail.
 Cases of blameless moral ignorance are arguably not confined to ancient history. We can point to cases of moral ignorance in more recent history that are plausibly blameless. Gideon Rosen offers the example of a 1950s sexist who, due to prevailing cultural norms, sees nothing wrong with the unfair differential treatment of his son and daughter (indeed, it may seem to him that the permissibility of his differential treatment is self-evident). As Rosen points out, we needn’t suppose that he is unreflective about his false moral views; we only need to suppose that, when he does reflect, the considerations to the contrary are bound to seem “wrong-headed” (2003, 66-68).
 Consider another, similar set of cases: two doctors each ignorantly prescribe medicine that a patient is seriously allergic to. The first doctor does so simply because no one is aware of the allergy, while the second doctor does so because he has negligently ignored the patient’s medical records.
 Philosophers often understand the term “attitude” broadly, to include beliefs as types of attitudes, in addition to more typical examples of attitudes (e.g., desire, resentment, indifference, gratitude, and so on).
 For articulations and defenses of this kind of position, see Elizabeth Harman (2011) and Angela Smith (2005).
 Matthew Talbert (2013) develops this response against Gideon Rosen and Neil Levy.
 This distinction is common in the literature, though some theorists use the term “factual ignorance” or “non-moral ignorance” to describe what I have called “circumstantial ignorance.”
 Elizabeth Harman (2011) maintains that moral ignorance never excuses, since moral ignorance itself always involves a morally objectionable attitude that is then expressed in morally ignorant wrongdoing.
 I am grateful to Nathan Nobis, Dan Lowe, Chelsea Haramania and Taylor Cyr for thoughtful dialogue and helpful feedback on this essay.
Talbert, Matthew (2013).” Unwitting Wrongdoers and the Role of Moral Disagreement in Blame.” In Oxford Studies in Agency and Responsibility: Volume 1, David Shoemaker (ed.): 225-245. Oxford: Oxford University Press.
Praise and Blame by Daniel Miller
Introduction to Consequentialism by Shane Gronholz
Introduction to Deontology: Kantian Ethics by Andrew Chapman
Free Will and Moral Responsibility by Chelsea Haramia
Alternate Possibilities and Moral Responsibility by Rachel Bourbaki
Free Will and Free Choice by Jonah Nagashima
Indoctrination: What is it to Indoctrinate Someone? by Chris Ranalli
Reparations for Historic Injustice by Joseph Frigault
Responding to Morally Flawed Historical Philosophers and Philosophies by Victor Fabian Abundez-Guerra and Nathan Nobis
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About the Author
Daniel Miller is a visiting assistant professor of philosophy at West Virginia University. His research focus lies at the intersection of ethics and the philosophy of action, including blameworthiness and ignorance, the ethics of blame, and free will. His work has appeared in Philosophical Studies, Pacific Philosophical Quarterly, Philosophical Explorations, and Philosophia. DanielJamesMiller.com