Sometimes the Truth is not Reasonably Believed

If a proposition is true, does it follow that it is rational to accept it? (Of course, if a proposition is known to be true, then it is eminently rational to accept it; but that's not the question.)

Hugh Hefner's death (27 September 2017) reminds me of a true story from around 1981.  This was before I was married. Emptying my trash into a dumpster behind my apartment building one day, I 'spied a big stack of mint-condition Playboy magazines at the bottom of the container. Of course, I rescued them as any right-thinking man would: they have re-sale value and they contain excellent articles, stories, and interviews.

I stacked the mags on an end table. When my quondam girlfriend dropped by, the magazines elicited a raised eyebrow.

I quickly explained that I had found them in the dumpster and that they contain excellent articles, stories, interviews, arguments for analysis in my logic classes, etc.  She of course did not believe that I had found them.

What I told her was true, but not credible. She was fully within her epistemic rights in believing that I was lying to save face. In fact, had she believed the truth that I told her, I would have been justified in thinking her gullible and naive.

This shows that truth and rational acceptability are not the same property. A proposition can be true but not rationally acceptable. It is also easily shown that a proposition can be rationally acceptable but not true.  Truth is absolute; rational acceptability is relative to various indices.  Rational acceptability varies with time and place; truth does not.

"But what about rational acceptability at the Peircean ideal limit of inquiry?" 

Well, that's a horse of a different color. Should I mount it, I would trangress the bounds of this entry.

As for Hugh Hefner, may the Lord have mercy on him. And on the rest of us too. 

_________________

*I am assuming that credibility and rational acceptability are the same property, where 'credibility' is defined as the property, not of being believable by someone, but of being rationally believable by someone. We should also distinguish between the credibility of persons and the credibility of propositions.  My quondam girlfriend did not question my credibility but the credibility of what I asserted.  Finding what I said incredible, she concluded that I was lying on that occasion; an occasional lie, however, does not a liar make.  A liar is one who habitually lies just as a drunkard is one who habitually gets drunk. Same with philanderers and gluttons. (But what about murderers?  It sounds distinctly odd to say, "Mack is no murderer; he murdered only one man.")

If a proposition is true, does it follow that it is rational to accept it? (Of course, if a proposition is known to be true, then it is eminently rational to accept it; but that's not the question.)

Hugh Hefner's death (27 September 2017) reminds me of a true story from around 1981.  This was before I was married. Emptying my trash into a dumpster behind my apartment building one day, I 'spied a big stack of mint-condition Playboy magazines at the bottom of the container. Of course, I rescued them as any right-thinking man would: they have re-sale value and they contain excellent articles, stories, and interviews.

I stacked the mags on an end table. When my quondam girlfriend dropped by, the magazines elicited a raised eyebrow.

I quickly explained that I had found them in the dumpster and that they contain excellent articles, stories, interviews, arguments for analysis in my logic classes, etc.  She of course did not believe that I had found them.

What I told her was true, but not credible. She was fully within her epistemic rights in believing that I was lying to save face. In fact, had she believed the truth that I told her, I would have been justified in thinking her gullible and naive.

This shows that truth and rational acceptability are not the same property. A proposition can be true but not rationally acceptable. It is also easily shown that a proposition can be rationally acceptable but not true.  Truth is absolute; rational acceptability is relative to various indices.  Rational acceptability varies with time and place; truth does not.

"But what about rational acceptability at the Peircean ideal limit of inquiry?" 

Well, that's a horse of a different color. Should I mount it, I would trangress the bounds of this entry.

As for Hugh Hefner, may the Lord have mercy on him. And on the rest of us too. 

_________________

*I am assuming that credibility and rational acceptability are the same property, where 'credibility' is defined as the property, not of being believable by someone, but of being rationally believable by someone. We should also distinguish between the credibility of persons and the credibility of propositions.  My quondam girlfriend did not question my credibility but the credibility of what I asserted.  Finding what I said incredible, she concluded that I was lying on that occasion; an occasional lie, however, does not a liar make.  A liar is one who habitually lies just as a drunkard is one who habitually gets drunk. Same with philanderers and gluttons. (But what about murderers?  It sounds distinctly odd to say, "Mack is no murderer; he murdered only one man.")