The party I`m running is in a logic puzzle escape room. None of my actual players are good with these. But, one my the Players is playing a Wizard with 20 Intelligence. He wants to know if he can roll as his wizard to figure out the answer. I think this is fine, but it got me thinking the other way round. Is it ok if a character with 8 intelligence suddenly becomes a genius at puzzles?

I'd say that this falls into the realm of metagaming.

Sometimes a player will know the monster they're up against. They'll be familiar with the creature's AC and abilities. In this case, we're going to need to remind them that their character might not. So nature, history, arcana checks are all useful here. 

In the case of the logic puzzle it's not dissimilar. Their ability score of 8 or 20 is sort of irrelevant. It would be their investigation roll for my money. Or maybe an investigation roll combined with a perception check. If the character beats the DC for an element of the logic puzzle you can then explain how they put two clues together to come up with part of the solution. Reminding the players though that they might know something but their character might not is an ongoing struggle sometimes. However, the flip side is there also being no harm in getting a player to roll and if their score is high filling in some of the blanks for them explaining that it was their character that worked this out.

So, to answer your question - it isn't their intelligence score that's useful here. It's the result of the roll on that ability check. I'd add in here that you should also consider allowing Wisdom rolls because they do include intution and there are people able to intuit solutions too. So, allow the players to roll either Int or Wis for their characters and base your responses off of that. After all if an INT 8 rolled a nat 20, that's still an 18...they maybe have just gotten really lucky and the character guesses the solution. A blind squirrel occasionally finds a nut after all.

I think this situation, of a player having higher mental abilities than their character, is one of the most challenging to roleplay. A similar situation is a player constructing an impassioned, articulate argument to sway an NPC, judiciously playing on their motivations and feats, then being reminded by their DM that their character has a Charisma of 7. 

I think the two ways that come to mind are: 

1) grant the character advantage on their ability check or

2) let the party use the idea as if coming from another character. Perhaps the Barbarian’s player solved the puzzle, but in-game the Wizard has the lightbulb moment. Alternatively, just enjoy the moment of astonishment when Brog the Brutal, who normally can only count to nine after that accident with his axe, spots the solution that the rest of party had missed. 

First, is your design of this puzzle something against the players, or their characters? 

If it is something for the characters, then rolls should definitely help inform the answer. 

Some puzzles (ie handing out a rubix cube and having someone solve it) go against the players though.  In this case, you may choose to use character rolls to help provide hints.  Or not, depending on what mood and idea you are going for.  Maybe the player behind the INT 8 barbarian is really good at puzzles and buy using a puzzle vs the players, they get a chance to do that as a normal break from what they normally do in game.   

As a previous poster mentioned, this does get into meta-gaming and what you problem you want the puzzle to solve :)

This is why I find puzzles, generally to be a problem. By design, they challenge the players and not the characters.

That said, most every time you put one out there, some player’s eyes light up and they love it. So there can be an upside. I guess the bottom line is, know your group and what kind of players you have. 

In the case of the OP, I’d say chalk t up to a learning experience that this group isn’t big on puzzles, and go ahead and let that 20 int character solve it. If you really want to move things along, just hand wave the whole thing. If you still want to make them put some work in, have them roll, and give them hints, clues, or a partial solve based on how high the roll is. There’s a big risk though, that they’ll flub the roll, and you’ll just be stuck in the room.

As far as an 8 int being bad at it. There’s a lot of answers. Partly, you’d need to trust the players to rp their characters. But even someone of below average intelligence might just be weirdly good at puzzles. So let them go with it. As I said at the beginning, you are challenging the players, not the characters, so just roll with what your players can do. 

So, I want to note that I suck at most puzzles. I get paralysis with riddles. I am good at scrabble but crossword puzzles infuriate me. 

I have three advanced degrees and some folks love to say I am smart. I don’t usually agree. Not out of modesty or humility — I can think of several dozen reasons I am not smart. 

a high intelligence does not make one good at logic puzzles. Indeed, a high intelligence often makes logic puzzles more difficult if they rely on areas of knowledge or skills outside pure logic — which can include language, vocabulary, and social mores.

As a DM, I advise strongly against logic or math puzzles when asked. As Xalthu notes, they are not things for the characters, they are things for the players, and in most cases rely on knowledge and concepts not readily solved in game mechanics or role play.

Any mental task should be handled by a roll. Puzzles, translations, stuff like that. You can use those rolls to simulate identifying clues, leaping to conclusions, and yes, it is cool to have script to translate for color, but making them do it should be a roll, not an exercise.

I do include puzzles in my game. I never make them a requirement to move forward, however — because if they fail all the rolls, then they are stuck. Just like if the players don’t think of a solution.

my puzzles always have things that provide the answer beforehand, as well. If a party comes before the infamous speak friend and enter, they will hear before hand several times that the people who would do that were direct people and gave explicit instructions.

because not everyone is good at even simple puzzles, and setting them as a requirement steals joy.

A puzzle you can't figure out is a very real way to not have fun. 

We play games to have fun. Any solution that helps stop not having fun and start having fun, is a good solution. 

Quote from AEDorsay>>

As a DM, I advise strongly against logic or math puzzles when asked. As Xalthu notes, they are not things for the characters, they are things for the players, and in most cases rely on knowledge and concepts not readily solved in game mechanics or role play.

Any mental task should be handled by a roll. Puzzles, translations, stuff like that. You can use those rolls to simulate identifying clues, leaping to conclusions, and yes, it is cool to have script to translate for color, but making them do it should be a roll, not an exercise.

I do include puzzles in my game. I never make them a requirement to move forward, however — because if they fail all the rolls, then they are stuck. Just like if the players don’t think of a solution.

my puzzles always have things that provide the answer beforehand, as well. If a party comes before the infamous speak friend and enter, they will hear before hand several times that the people who would do that were direct people and gave explicit instructions.

because not everyone is good at even simple puzzles, and setting them as a requirement steals joy.

 And game-blocking puzzle needs an NPC as a backup, and that just ruins the players' fun

When my players get stuck on a puzzle I let them make a character roll and give them a hint as an insight the character had.

When players are more informed than their characters I don't do a thing other than let it happen with a smile. Every dog has it's day and it keeps the game moving.

As others have said, typically D&D puzzles are designed to challenge players, not characters. It's a different kind of fun separate from roleplaying, like a mini-game.

A puzzle designed to challenge players is basically a skill challenge, which is a valid thing but is a very different kind of engagement.

If your players like puzzles, it might be worthwhile to have a side discussion about how you want to separate the "players-figuring-out-the-puzzle" discussion from the "characters-overcoming-the-obstacle" scene. You could let them solve the puzzle and then separately figure out how the party came to the same conclusion. Just because the girl playing the barbarian figured it out doesn't mean her character was the mastermind behind the solution. Or maybe they'd get a kick out of narrating a scene where the barbarian gets frustrated and throws her axe, which just happens to bounce off the right sequence of glyphs to open the door.

Quote from Agile_DM >>

When my players get stuck on a puzzle I let them make a character roll and give them a hint as an insight the character had.

When players are more informed than their characters I don't do a thing other than let it happen with a smile. Every dog has it's day and it keeps the game moving.

 sometimes i wish there were a hard-earned forums currency so i could leave a two-pence tip on a particular reply for succinct wisdom. alas...

🪙🪙