I'm not talking about when a character with a -2 to athletics tries to make a big jump or some such. That's just poor decision making and a probably (or maybe automatically) failed roll.

I'm talking about things like when a player uses their own intelligence to come up with an idea that would require a stat of, say, 15 intelligence to come up with and wants us all to pretend their 3 intelligence character came up with it.

My first impulse is to be like "Jerry you have 4 intelligence, your character is stupid, stop trying to be smart."
But I worry that would be met with "DM why are you trying to steal my player agency"

Another idea I had, and am not sure about, it that whereas a dice roll helps determine the success of an attempt at something, I could use the characters stat to determine if the idea was a good or bad one in the first place.

So for example the party comes across a cliche bridge troll/demon/whatever that says "I will allow you to cross if you make a deal with me."
One of the players says to the it "can you wait a few seconds" thinking if it says yes it will count as the deal and they get to cross.
An intelligent character rolls persuasion to see if it agrees to wait or not, and if it does the plan works and they get to cross.
A stupid character rolls persuasion to see if it agrees to wait or not, and if it does when they try to cross it laughs at them for being dumb enough to think that would count as their deal.
Mind you this isn't the best example because I can't help but think that plan is stupid and wouldn't work regardless, since actually making deal would require genuine agreement understanding it is the deal being agreed upon.

That is simple bad roleplaying.

In general I dislike the role-players complaining about min-maxing, because in truth every single soldier in the entire world tries to min-max.  You ask a marine which weapon is best and he will spend 30 minutes explaining why his favorite is the best in the world.

But if your character has an int of 3, yeah, that guy should be insisting that his Barbarian needs to use a tree as an improvised weapon, because look how BIG it is, despite the fact it still does 1d4.

Even a dumb character has a good idea once in a while. Perhaps you could use your system, but also secretly roll intelligence for the character that came up with the idea. That way a dumb character can have a good idea and a smart character can have a bad idea, even if it's most of the time the other way around.

You are correct Wooby.   (insert joke about timing here)

But the Player that does this does not do it once a level, they do it every game.  Because they are not trying to play their character's stats.

Quote from Mog_Dracov >>

In general I dislike the role-players complaining about min-maxing, because in truth every single soldier in the entire world tries to min-max.  You ask a marine which weapon is best and he will spend 30 minutes explaining why his favorite is the best in the world.

 I don't understand what you mean by Role-Players complaining about Min-Maxing.  Could you flesh this out for me?

As for the Marine ... I served in the military.  I have a list of weapons I prefer over others, but I would not think they are the best weapon for any situation, although they might be the best weapon for a specific situation.  I could tell you why I liked that weapons system but I could accept that they were not the best; just the best weapon I would want to carry under a set of circumstances.  So in urban combat, a soldier might think a pump action shotgun was the best while another might think an M-4 was the best.  I'd like to understand what you mean.

I think if your player wants their character to do something that seems too intelligent for their character, you could have them roll an intelligence check to see if their character could have come to that conclusion. Like... let's say you come across some chemicals in a laboratory, and you discover some pure Sodium. You know what happens when Sodium comes in contact with water... but that doesn't mean your character would. A character with a 3 in intelligence and no prior experience with chemicals could, at best, make an intelligence check at disadvantage to try and remember something cool they saw happen once.

Keep in mind that low intelligence doesn't necessarily make someone a complete idiot. Intelligence, in D&D terms, is mostly a measure of your character's ability to recall specific facts and information. A character with low Int but solid Wis could make a solid plan through common sense and intuition, even if they don't know all the words for everything they're suggesting.

Are you just exaggerating or do you really have a character with a 4 INT in your party? And if so why did you even allow it? As a DM you should realize that 4 INT is roughly equivalent to an animal, and would be very hard if not impossible to RP correctly. You should only allow this if the player is an outstanding RPer and has agreed to play his character like an animal who barely understands simple words and cannot speak in full sentences. If he has not agreed to this you should not allow him to take a 4 INT.

Presumably with the 4 INT, something good is making up for it (e.g., 20 STR). If so, then that is the trade-off. If the player choose to get uber STR by sacrificing INT, then the INT is sacrificed. He can't come back now that he has a 20 STR and RP his INT as average. It's not. He's got the comprehension ability of a wolf.

Quote from BioWizard >>

Are you just exaggerating or do you really have a character with a 4 INT in your party? And if so why did you even allow it? As a DM you should realize that 4 INT is roughly equivalent to an animal, and would be very hard if not impossible to RP correctly. You should only allow this if the player is an outstanding RPer and has agreed to play his character like an animal who barely understands simple words and cannot speak in full sentences. If he has not agreed to this you should not allow him to take a 4 INT.

Presumably with the 4 INT, something good is making up for it (e.g., 20 STR). If so, then that is the trade-off. If the player choose to get uber STR by sacrificing INT, then the INT is sacrificed. He can't come back now that he has a 20 STR and RP his INT as average. It's not. He's got the comprehension ability of a wolf.

 My old paladin had a horse smarter than that PC. My IRL dog knew dozens of commands in 4 languages including a form of sign language, and a series of whistle signals, he probably had an Int higher than 4. That is tough to role play. Anything lower than 6 is soooo hard.

Quote from BioWizard >>

Are you just exaggerating or do you really have a character with a 4 INT in your party? And if so why did you even allow it? As a DM you should realize that 4 INT is roughly equivalent to an animal, and would be very hard if not impossible to RP correctly. You should only allow this if the player is an outstanding RPer and has agreed to play his character like an animal who barely understands simple words and cannot speak in full sentences. If he has not agreed to this you should not allow him to take a 4 INT.

Presumably with the 4 INT, something good is making up for it (e.g., 20 STR). If so, then that is the trade-off. If the player choose to get uber STR by sacrificing INT, then the INT is sacrificed. He can't come back now that he has a 20 STR and RP his INT as average. It's not. He's got the comprehension ability of a wolf.

 Some groups choose to strictly role stats, which could leave you with a 3 (4d6 remove lowest).

I have not personally been dm for such an extreme as a 3 int character trying to do things that would require high int to think of, but I see less extreme versions of this premise with some regularity. 

Even so, there is no reason for a 3 INT character to be played as if he is intelligent.

Personally as a DM I would not allow such a bad stat. But then I use stat arrays or point buy, or if I used rolls, I would do something like, allow you to re-roll if you got no more than 2 on any of the 4d6.

Quote from BioWizard >>

Even so, there is no reason for a 3 INT character to be played as if he is intelligent.

Personally as a DM I would not allow such a bad stat. But then I use stat arrays or point buy, or if I used rolls, I would do something like, allow you to re-roll if you got no more than 2 on any of the 4d6.

 I agree,  3 INT is barely (if at all) sentient. 

There are some fundamental problems with D&D stats that overlap with the player’s real “abilities,” but that aside, the biggest complaint I have about abilities is how one-dimensional people see them as. A low intelligence could mean a lot of different things: really bad memory, poor reasoning skills, poor insight into deeper topics, really bad in some specific intellectual skill area. It doesn’t have to mean bad in all of these. Remember that this is an abstraction. You can’t define an individual with six variables. Leave the stats for rolling: recall, insight, ability challenges, perhaps a game outcome. 

think you need to just not see 

Yes, abilities are abstractions. But even a Cat has a 3 INT, and a baboon has a 4, and an ape has a 6. So it is hard to argue that a human or an elf with a 3 INT would be somehow otherwise normal but just have a really bad memory like Dory from Finding Nemo. 

Right. So if a 3 or 4 means that to you, don’t permit it for a character.  It will be unplayable.

By that same token, a character with an 18 intelligence will have perfect 100% recall, no problem is unsolvable, with perfect insight into every dimension of every situation and able to connect every subtle relationship effortlessly. A player can just go on autopilot and you just tell them everything you have planned as it emerges. That level of intelligence is way beyond both the module designer and the player.  If we don’t do this at that end of the spectrum why would you stress about the lower end. 

Look at it this way: Int lets you recognize that it’s raining, Wis tells you to bring an umbrella. If you’re not even smart enough to realize it’s raining, that make it hard to RP.

It’s kind of a weird question, just because who is to say how smart is smart enough? Outside of the extreme examples, like a 4 int or someone, I don’t know, inventing calculus, it seems arbitrary to decide one score is high enough to think of something but another isn’t. 
In the original example, if a character has a 12 or a 14, would you say, no, you need a 15 to think of that? 
And in practical terms, I’d guess most characters will have between a 8-14. Basically wizards are likely to be the only characters with an int over 14, that’s most everyone unable to think of these things. 
So while agree it’s probably bad role playing if your kind of dim character has tons of good ideas, as a DM, I’d just go with it. 

When your Int is literally lower than an animal’s, it’s a different story.

Quote from IamSposta >>

When your Int is literally lower than an animal’s, it’s a different story.

 Agreed.  But that’s going to be a pretty rare edge case. Even rolling for stats. It’s possible but going to be rare. 

Quote from Xalthu >>

Quote from IamSposta >>

When your Int is literally lower than an animal’s, it’s a different story.

 Agreed.  But that’s going to be a pretty rare edge case. Even rolling for stats. It’s possible but going to be rare. 

 That’s what we are discussing, an Int 3-4 PC.