According to Hugo Grotius, it is not immoral to lie to someone who does not possess "the right to exercise liberty of judgment". He then proceeded to give two examples: (i) you cannot lie to a madman (ii) you cannot lie to a child. The argument is that lying is only immoral when it constitutes "Violation of Real Right" and these entities do not possess such a right because of their limited capacity.

So, is it correct for me to infer that it is less immoral to lie to those who are less intelligent, because they are less capable of or less likely to resort to this "exercise of judgement"? An analogous argument to Grotius' would be that it is less immoral to lie to a 3 year old than a 6 year old because the former does not possess much ability to comprehend. But age, as opposed to intelligence, is not a factor here. So we are essentially stating that it is more immoral to lie to a person with higher IQ (generalizing the 6 year old) than a person with lower IQ (generalizing the 3 year old).

The practical implication is that, if I were to run a scam, it would be less immoral for me to prey on more vulnerable groups, e.g., older people, or less educated people, compared to scamming people who are less vulnerable, say, other scammers (simply because they are well versed in the trade of scamming and possess a stronger ability to judge a situation of scam). This does not match my intuition very well.

So, is this "moral deceptionism" theory by Grotius a fallacy or is it that I do not understand him correctly?

  • @DavidBlomstrom It seems to me that the more vulnerable a group of people is the less people care about their misery and tend to abuse them more. I feel Grotius's way of thinking is not unique to himself. Many people believe that you "deserve" to be scammed if you are that dumb and they are more than justified to scam you morally.
    – Daniel Li
    Sep 19, 2019 at 1:31
  • @DavidBlomstrom I do not think many people genuinely sympathize with physically handicapped either. It is more common that they tend to be indifferent because such people are useless to their cause. Meanwhile, they can exploit people who are not intelligent, to whom their attitude appears to be more ruthless--this is logical because they play a predatory role here unlike the former case.
    – Daniel Li
    Sep 19, 2019 at 2:03
  • It depends on the purpose of the lie. If it is a so-called "white lie", as in saying something untrue because the person in question is judged incapable of grasping the truth, but can be comforted, or induced to act to their own benefit by the lie, then, perhaps, it is moral (or not even a lie, for Grotius). If, on the other hand, it is to run a scam on the vulnerable, then it is not (they have a "right to know" it is a scam). See Skalko's Contra Hugo Grotius.
    – Conifold
    Sep 19, 2019 at 9:29

2 Answers 2


A lie is a lie, morally, socially, or otherwise. Even the less intelligent will find out that a lie is a lie. It just takes more time. Worse, the liar has somehow suggested that you can lie. We have a commitment to this and generations to cherish truthfulness and honesty irrespective of the consequences.

  • I don't believe truth at any expense is a good idea. Literally, you're saying we have to stop all movies, books, plays, comedy, and even art. Every time you say something you know is false becomes wrong? It just doesn't work that way, and this was what Hugo Grotius was getting at.
    – Vogon Poet
    Sep 19, 2019 at 12:44

Briefly, no. According to Grotius an act is no more or less moral than another in the way a mother was no more or less pregnant with you or your sibling. "Moral deceit" - like a joke or fiction story - is simply a false statement which hurts no one.

Why no moral relativism?

This question is a non-sequitur. It assumes some scale of morality designed by Grotius, who was arguing Christian aspects of morality:

"an act is either forbidden or enjoined by the author of nature, God." - Grotius

He states that one act is either immoral, or it is not. There is no gradation.

Since Grotius' work derives from the Bible, the proper treatment of immorality is the concept of sin. As such, in James 2:10, it states,

“For whoever keeps the whole law and yet stumbles at just one point is guilty of breaking all of it."

Therefore, it is not possible for one immoral act to be more or less immoral than another. There is sin, and there is sinlessness. No one "almost" gets salvation and there is no priority on the list. If you bear false witness on a child, a thief, a deaf person, a politician, or a pope, the consequences are equal.

Note that not all lying is bearing false witness. Lying and false witness are different concepts. Lying to a child about Santa Clause for example is not false witness for the reasons Grotius argues - no rights are diminished. For this same reason jokes and fiction are not false witness.

Also, your scam scenario is always immoral regardless of the victim. That's by definition of a scam.

  • I thought someone may rush right into the "binary morality" argument, which may sound clever but is essentially nonsensical. Is it equally bad if I steal one dollar from a person as I kill his whole family and burn his house down? It is very tragic that some people think that blindly and predictably.
    – Daniel Li
    Sep 18, 2019 at 22:24
  • It's predictable because it is also true, based on the works of Grotius himself. Maybe choose a different reference arguing for the merits of moral relativism? Sorry you don't like the answer, but you can answer yourself and see how the vote turns out.
    – Vogon Poet
    Sep 18, 2019 at 22:27
  • As I have stated in the post, I'm not an advocate of Grotius' views and do not intend to take his opinions as a "reference". I was merely evaluating merit of his argument.
    – Daniel Li
    Sep 18, 2019 at 22:29
  • And I gave the evaluation. You asked if he intended some scale of immorality, the answer is "no."
    – Vogon Poet
    Sep 18, 2019 at 22:30
  • How the votes turn out does not make your answer more true or more false.
    – Daniel Li
    Sep 18, 2019 at 22:30

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