Can you argue against a moral absolute by saying yes it's rational, but not practically so?

Can you argue against a moral absolute by saying yes it's rational, because it's true, but not practically so?

So can you, in principle, coherently claim that it is true that not lying is good, and so the obligation not to lie is rational, but sometimes it is rational to lie?

I hope so, though I'm probably wrong.

Perhaps practical moral skepticism can account for it being moral to lie to save the fugitive, but in this instance there's no rational need to be moral. Wouldn't that mean lying is irrational but not practically so?

As to why believe (at all) in practical moral skepticism, couldn't something like 'relevance' temper the irrationality of moral actions? A watertight mathematical proof sounds supremely rational, but sometimes irrelevant, and so sometimes it is irrational to work on it. Why not, analogously, performing moral actions?

• I would say no because the scenario here is the moral absolute is still correct and this is not under dispute. Your focus on practical indicates that you might allegedly rationalize to do something you KNOW is wrong to prevent a negative result from occurring to you. I.e., you commit adultry and the video leaked but you try to lie and say it's not you to prevent divorce. The objective truth remains intact. You are just trying to be slick and get away with stuff. You can lie to save someone from being murdered. This again is practical but only to prevent undesirable results. Just come clean. Mar 29 '19 at 17:26
• no, i'm talking about lying to stop a murder. this seems to be a conclusion from kant, just one he may have missed? we can't just ignore it and hope it goes away... @Logikal
– user38026
Mar 29 '19 at 17:27
• You ate likely confusing truth value with the result. The two are independent of each other. The same way you can't combine different variables in mathematics. Because x is practical some of the time does not make x morally correct. As a matter of fact it proves unreliable. Absolute means the value cannot change over time with given circumstances. This is summarized with the term objective. Objective means x is always right or wrong in the exact circumstances given without exception. One false case proves the the method unreliable and untrustworthy. A person makes an error doing so. Mar 29 '19 at 17:37
• i'm confused, i never mentioned truth value, or result @Logikal
– user38026
Mar 29 '19 at 17:39
• The purpose of you mentioning the practical has nothing to do with the result?? Why bring it up then? Morals have truth values by definition so you dont have to literally mention it. Practical implies results and moral implies objective truth value. Mar 29 '19 at 17:42