Love of a good mystery accounts for the spectacular popularity of "Serial," but the value of the podcast extends far beyond satisfying our curiosity about whether the right guy is serving a life sentence for murdering a Baltimore high-school girl in 1999.

In a rush-to-judgment world, "Serial" reminds us, in its plodding, excruciatingly detailed way, of how hard it is to find the truth.

Who's lying? Who's misremembering? Who's misperceiving? Who's assuming?

Who knows?

Journalism, jury trials, scholarly research, indeed the entire social contract, are predicated on the notion of reliability — that we can trust people to tell the truth, to keep their thumb off the scale, to stop at stop signs.

But we are not a very reliable species.

Yes, there is evidence, but people are the collectors and interpreters of evidence.

Think of a baseball game played without an umpire. Batter hits a groundball. Ball and runner arrive at the base at roughly the same time. The team in the field is certain the runner is out. The team at bat is just as certain the runner is safe. Both sides insist that their perception was not influenced by their interest. They think the way they saw it is the way it was. They are only asking for what is theirs by right.

Now add an ump. On the face of it, the man in blue is the more reliable source. For one thing, he was closer to the action. For another, he is supposed to be a disinterested party.

Has that ever stopped a manager from pressing his case? Perhaps Blue had a lapse of attention. Perhaps he meant to give the safe sign but made the out sign by mistake. Perhaps he needs new glasses.

Indeed, replays have shown that umpires sometimes get it wrong. Acknowledging that possibility, Major League Baseball this year introduced an appeal process. Given enough camera angles and nifty stop-action technology, an official (and we, the audience, seeing most of the same angles and stopped action) can usually settle the matter. But not always.

Out there in the messy world, meanwhile, even with the ubiquity of cellphone cameras, most events go unrecorded. If we want to find out what happened, we must rely on unreliable perception and unreliable memory.

It's a scary thing that we routinely send people to prison for life on the basis of nothing more substantial than the believability of a "witness."

Have you ever had someone attest to another person's honesty by saying something like, "He looked me right in the eye and swore he was telling the truth"? The last time that happened to me, the supposedly honest person was one of the Penn State University administrators who are awaiting trial on charges that they ignored or actively quashed the allegations of child sexual abuse against former football coach Jerry Sandusky.

Now it's entirely possible that the administrator in question was telling the God's honest. But I had to laugh: People look other people in the eye and lie through their teeth all the time!

Case in point: whoever in the Russian military or diplomatic hierarchy gets asked about tanks, troops and materiel seen pouring across the Russian border into eastern Ukraine. Not happening, say the Russians. But the satellite images? The eyewitness accounts of reporters on the ground? Nyet.

The audacity of these denials is impressive. While our courts quaintly make witnesses promise to tell the whole truth and nothing but, and our moral authorities promote honesty as a virtue, the real players — in politics, in business, in sports — make lying a core strategy for making one's way in the world.

Given rampant dishonesty and the fallibility of perception and memory, one would think we would be more like my friend Sarah Koenig, the producer of "Serial": more skeptical and more methodical in our truth-seeking. Instead, what we see over and over, in Rolling Stone's University of Virginia gang rape story, in our assessments of guilt or innocence in the killing of Michael Brown in Ferguson, Mo., in the Jerry Sandusky case at Penn State, are snap judgments.

"Serial" may be teaching that the truth, maddeningly, is often unknowable. Or it may be teaching us that it just takes a good long while to tease out.

Frank teaches journalism at Penn State University.