Is it always more rational to act according to one's beliefs than to refrain from acting on them?

  • 5
    If you have an irrational belief, would it be rational to act on it? Jun 29, 2021 at 22:19
  • 3
    'Beliefs' is a pretty vague term.
    – CriglCragl
    Jun 30, 2021 at 6:12
  • You ask two different things. Jul 1, 2021 at 2:21
  • @KristianBerry What is the difference between an irrational belief and simply a wrong one?
    – Sam
    Jul 1, 2021 at 11:32
  • @Sam What is rational is determined by what you know. Consider the following. Believing there are aliens on Mars is generally regarded to be irrational. However, if tomorrow, an alien spaceship (emblazoned with "from Mars") greets you on your doorstep, your new knowledge will rationally support a belief in Martians. This belief would have been correct the day before you saw the Martians with your own eyes, but it wasn't rational then. For the converse, I'm sure you can construct a rational but incorrect belief yourself. Jul 6, 2021 at 19:16

5 Answers 5


If a person experiences cognitive dissonance, and has two (or more) beliefs that are in contradiction with one another, it cannot be rational for them to act according to both. Refraining from acting on at least one of that pair of beliefs is necessary for such a person to act rationally, in the absence of jettisoning at least one of them.


Yes, at least in the absence of cognitive dissonance as mentioned by Sofie.

That is because to act rational, we have to follow the "best" action according to our knowledge. Since our beliefs are the prior we assume about the world (I think we can simplify it like that), it would be irrational to act against them. Note also that beliefs may not be binary. A belief could be "I believe there is a 90% chance it is not going to rain", but the person also values not getting wet 10x higher than the inconvinience of bringing an umbrella if it doesn't rain, so they bring an umbrella.


No, because the law dictates that some expressions are "unlawful".

It's generally e.g. unlawful to act on an impulse to kill, even if you would find it "rational". Yet a serial killer may well claim that "they act based on their rational". But their rational is unlawful.

You may debate on moral philosophies, but a "normative idea" is that norms only make sense, if everyone is forced to obey them through expecting others to obey them. It's not about "your rational" or "my rational", but that we have agreed upon, which rationalities we don't want to be applied on us. And those who make an exception to such rule are breaking a social contract, even if they have an individual rational. So i.e. an individual reason cannot overarch a collective rule.

I find racism rational in some cases. It doesn't seem to justify being racist though, even when I find it rational. So is "my rationality" enough? Again if you ask the law, it's not, if it's not legal. I can still believe it to be right, but if the law says it's not, then I should not act on it.


The answer is straightforward (if you really meant what you've asked): YES.

Explanation: The question is essentially a pleonasm.

Acting according to a belief is rational, because rational decisions (and further actions) are based on subjective knowledge (which is not necessarily shared knowledge, not necessarily scientific knowledge, etc.); and subjective knowledge is essentially a set of beliefs.

So, you are basically asking if "acting according to [subjective] reason is rational". And regarding "subjective reason": there's no other. Then, the question is if "acting according to reason is rational": that is a pleonasm, like asking if we smile with a smile.


We have beliefs, some stronger, some weaker, and sometimes we are wrong. If you always follow your beliefs then sometimes you will get it wrong, and sometimes the outcome may be fatal.

So you don’t just unconditionally follow your beliefs as a rational person, you will also consider the possibility that you are wrong. The probability that you are wrong, and how bad the outcome would be if you are wrong.

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