Two shakers no markings. One has fewer holes in it than the other. Which one does the salt go into and why?
Salt pours more easily, and therefore needs fewer holes for you to put enough on your food to obscure whatever taste it might otherwise have had. Pepper, which is relatively harder to pour, goes in the shaker with more holes.
It appears that you registered JUST to posit this question. I LIKE that!!
here is the answer. The one with the fewer holes is for salt. Reason, salt “flows” more easily than ground or cracked pepper. (Just watch people at tables with S & P shakers w/same # of holes, they shake pepper more violently)
The fewer holes is to limit/restrict the amount of salt so you don’t OD on the salt. It’s easier to add more salt than to remove some.
Spicely,
Spritle
WELCOME TO THE BOARDS!!! May I take your coat? You’ll find chips on the table and a keg in the kitchen.
BTW, If you knew the answer to this question, you wouldn’t mistakenly put too much salt on your food. If you didn’t put so much salt on your food you wouldn’t be Thirsty!
Damn! Cantrip beat me to the post, but I was the first to welcome you. Remember that when it’s time to by presents for SDMB dopers!
I guess this will just bring things back to an indeterminate state, but I’ve always done it the other way around. Generally, people are more liberal with salt, so they want more to go on with each shake. So it gets more holes.
I believe if you look at a set that is marked for salt and pepper, most of the holes are on the salt shaker.
My wife and I have a set of shakers without the “S” or “P”, but have 3 and 4 holes. We put salt in the 3-hole one.
But when my mom came to visit, she thought it should’ve been pepper. She didn’t figure out our usage until she shook a lot of salt on her salad, waiting for dark little pepper flakes to finally appear.
Now, I remember my mom’s sets of shakers. They all had multiple holes on one and one big hole on the other. Using sets like those, yes, I would put the salt in the multiple-holed one. Otherwise, the salt would just pour out of the large 1-hole shaker.
But when they’re both multi-hole (and the holes are the same size), salt should go in the lesser-holed one.
IMO
Mrs. Jingo (who is excruciatingly well bred) says that the salt/pepper thing is the result of the Victorian habit of making every little thing have it’s own cute little precise purpose. This was particularly true of table settings (witness the bewildering array of silver and plates at a proper Victorian setting: olive plates, asparagus plates, sherbert spoon, shrimp fork, etc, etc.) and a diner was expected to know the proper use for everything.
That said, often the sole difference between the salt shaker and pepper shaker is the size of the holes. Same number—but the pepper holes are bigger than the salt holes. This is due to the size of the granules, as already mentioned. I would tend to agree, for the same reason, with the idea that the lesser number of holes gets the salt.
I was going to ask her where I could find a cite, but she began to wax philosophically about candelabrum placement. Bless her heart, but I was forced to hang up on her. 
And yes, Dave Barry, ‘The Pepper Holes’ would be a good name for a rock band.
Damn, where are my manners? Thanks, spritle, for picking up after me.
Would you like a martini? Shaken or stirred?
The inlaws believed in the more people use salt, so salt goes in the shakers with the most holes.
I told them they were wrong because if they did it that way the pepper would clog up the few holed shaker. This is also the reason why they don’t put pepper on anything.
I also have a feeling that salt is not used more than pepper at the table, and that would really blow the usage theory out the window. Know where i can get numbers?
Bah.
The food should be properly seasoned before it leaves the kitchen.
Destroy ALL salt and pepper shakers!
(and you shouldn’t be eating pre-ground pepper, anyway. use the peppermill.)
OK, now I have to get all historical and all.
Gee, Mr. Peabody, what’s the Way Back machine set for today?
The Age of Discovery, Sherman. We’re going to look at the “discovery” of spice. Then, we’ll go back to the Middle Ages (roughly).
Salt was very 'spensive. Possession of salt was a bit of a sign of wealth. Wasting salt was quite taboo. If someone was useless (like a football bat) they were not worth the salt in your tears. Yes, Sherman, salt ruled.
When people saved for years to afford a portrait (No Olan Mills back then) they would pull all of their trappings of elegance into the picture. Check out Van Eyck (sp?). Those posing for the pictures would pose next their bed (if they had a frame, wear red (very expensive dye) and other such displays - including putting the salt mill in the picture.
Being expensive (not just valuable), one did not want to waste salt. Thus, fewer holes in the shaker.
On the other hand, spices were like currency. Using a lot of them was a sign of affluence. Translation, more holes.
Se non e vero, e ben trovato
Shakily,
Spritle
(please don’t bust me out for the part about them not having salt shakers back then!)
I always put the pepper in the shaker with more holes, otherwise you can’t get enough out in a reasonable time.
I have to disagree with Ike about serving food, the problem is that “properly seasoned” varies greatly between individuals, and it’s much easier to add salt to a dish than to remove it.
There’s another issue here, salt and pepper were added at the table because they were expensive, and adding it to a dish during cooking, or mixing it into the food, is wasteful. Only the salt which actually contacts the tounge is tasted, any other salt is eaten but not tasted. By adding the salt to the surface just prior to eating, the minimum amount of salt is required to reach a “salty” taste.
Also, after the tounge has been stimulated by a strong salt taste it continues to report this taste for some time, thus if only the first few bites are salty the rest of the dish will taste saltier as well.
I’ve argued this repeatedly to people with high blood pressure who give up salting food at the table but continue to buy the same high-sodium brands of soup, veggies, etc. These people complain that they can’t salt their food, but they would consume much less sodium if they would buy low-sodium brands and salt at the table. They could not-have their salt and eat it too.
Yeah? Listen, pal, you come to MY house, you eat as much salt as I say!
(Oh, c’mon…that was tongue in cheek. I get tired of my wife telling me “You can salt it at the table!” though…dammit, it TASTES different when you add the salt earlier in the cooking process!)
spritle: I don’t think salt shakers turned up until the 19th century…a salt BOX in the kitchen was the norm earlier on.
If only the fast food restaurant owners would realize that. Giving me Semi-cold fries and a packet of salt is nowhere near as good as a fry properly salted while the grease is still sizzling.
Hey, I get to catch Ike for once!
Any gourmets worth their salt also use a salt mill as well. The flavor of freshly ground sea salt is wonderful.
The set I have has a 4-hole shaker marked “S” and a 3-hole shaker marked “P.” Even if they weren’t marked, we’ve ALWAYS put the salt in the one with more holes. To tell you the truth, I don’t know why, but that’s always been the way I’ve seen it.
I’ll be the first to agree that pepper should have more (and larger) holes, but in actual fact, whenever I see shakers differentiated only by number of holes, the salt is always the one with more (except at my sister’s house: She reasons that “pepper” has more letters, and thus more holes).
And why is it that when you get single-serving packets of salt and pepper at a fast-food place, the salt is always five times bigger or so?
If you go to a fast food place and check out the little packets of salt and pepper, you will find that there is much more salt than pepper in each packet. This would imply to me that people like to have at least twice as much salt on their food than pepper. Even though the shakers came first, I believe that the shaker with the greatest number of holes if for the salt and the one with the least holes if for the pepper. 
( Unless you come from a family that loves pepper and goes real lite on the salt)Then you reverse my conclusion.
Actually, black pepper was once literally worth its weight in gold. Salt, while it used to be expensive, was never THAT dear.
Particularly for salads, salt from a grinder nestles in the leaves very nicely. But the pepper thing is much more important. The stuff from shakers is horrible dust. Grind your own, it’s still dirt cheap. Even the groovy Sarawak peppercorns are only about $5 for a year’s supply.