And besides if the hidden character is behind total cover, they cant shoot their enemies, and enemies cant shoot them, so it doesnt matter. What matters is when the assasin who hid behind total cover comes to 3/4 cover or comes out in the open to attack you. At which point, if passive perceptiin is always on, that when you percieve them, and they cannot attack with advantage.
Actually, 3/4 cover is explicitly mentioned as being good enough to potentially conceal your location by successfully hiding. As such, when the assassin who hid behind total cover (and has not yet been passively or actively found) comes to 3/4 cover to attack you, that attack does not reveal their location until the attack hits or misses as per the rules for Unseen Attackers and Targets combined with the rules for hiding. If the passive perception did not already detect this creature, it would not help them in that situation.
"that text does NOT say that that is the only way to find a creature,"
The way the rules work, the only thing you can do are things the rules say you can do. So, if the rules say you can misty step as a bonus action, then you can misty step as a bonus action. The rules will NEVER say that will be the only way to misty step, cause some subclass or feature might let you do it someway else.
BUT, unless therr is a rule somewhere that says you can misty step as a reaction, then all there is is the rule that says you can misty step as a bonus action, then bonus action is the only way you can do it.
The rules for Hide willl NEVER say that Search Action/Perception Check is the ONLY way to find someone hidden, but unless there is actual text rules that give another way, then there is no other way.
So unless there is a rule that says you can "find" someone who is hidden using your passive perception, then it isnt raw. It may be rai. But if its rai, then raw needs errata to clarify
And besides if the hidden character is behind total cover, they cant shoot their enemies, and enemies cant shoot them, so it doesnt matter. What matters is when the assasin who hid behind total cover comes to 3/4 cover or comes out in the open to attack you. At which point, if passive perceptiin is always on, that when you percieve them, and they cannot attack with advantage.
Actually, 3/4 cover is explicitly mentioned as being good enough to potentially conceal your location by successfully hiding. As such, when the assassin who hid behind total cover (and has not yet been passively or actively found) comes to 3/4 cover to attack you, that attack does not reveal their location until the attack hits or misses as per the rules for Unseen Attackers and Targets combined with the rules for hiding. If the passive perception did not already detect this creature, it would not help them in that situation.
My comment was in response to
"You can find a hidden creature behind Total Cover if you meet its Hide DC with a Wisdom (Perception) check or if the DM uses your Passive Perception instead and it's high enought to do so."
I.e. total cover.
To which i was agreeing that you could find someone behind total cover.
The way the rules work, the only thing you can do are things the rules say you can do.
First of all, this is false. If there had to be a rule for every possible thing that you could do, then the rulebook would be infinitely long. Where is the rule that says that you can paraglide? Where is the rule that says that you can swing back and forth while grabbing a chandelier? Where is the rule that says that you can bake a loaf of bread? There are an infinite number of things that creatures can do that are not explicitly stated within the rules.
So unless there is a rule that says you can "find" someone who is hidden using your passive perception, then it isnt raw. It may be rai. But if its rai, then raw needs errata to clarify
No, the 2024 rules made a deliberate effort to avoid repeating things in multiple places. There is no reason for the text of the Hide action to address this at all. The Hide action provides a mechanism for determining how to adjudicate a Search action to find a hidden creature. There are already rules elsewhere that establish that Passive Perception is used to notice creatures and objects when not actively searching. So, setting the DC explicitly for the Search action also implicitly sets the DC for Passive Perception, by rule. This is because the DC is a property of the thing being found, not a property of the method of finding it. Any time it is possible to actively search for something you might also discover it passively. That's RAW.
A similar issue arises when people like to claim that taking the Hide action "only" gives you the Invisible condition. This is false. It's just that the other rules and mechanics for hidden creatures are located elsewhere -- therefore, they do not need to be written into the text for the Hide action. The Hide action establishes that you become a hidden creature. In the rules for Unseen Attackers and Targets we learn that the location of a hidden creature is unknown specifically because they are both unseen and unheard. Therefore, the act of becoming hidden means that you become both unseen and unheard. An additional consequence is that you also gain the invisible condition -- that detail is not given anywhere else, so it has to exist within the text for the Hide action. In the 2024 rules, this sort of thing happens all over the place because the authors tried very hard to save word count by avoiding redundancy.
The way the rules work, the only thing you can do are things the rules say you can do.
First of all, this is false. If there had to be a rule for every possible thing that you could do, then the rulebook would be infinitely long.
First of all, no, this is exactly how the rules work. If the rules spell out all the ways a character can make an attack, and those rules say that your character can make 4 attacks, then you cant argue that there is no rule that PROHIBITS you from making a 5th attack therefore 5 attacks within the rules. That is the textbook example of an Argument from Ignorance logical falacy. "The fallacy is committed when one asserts that a proposition is true because it has not yet been proven false"
Where is the rule that says that you can paraglide? Where is the rule that says that you can swing back and forth while grabbing a chandelier? Where is the rule that says that you can bake a loaf of bread? There are an infinite number of things that creatures can do that are not explicitly stated within the rules.
"Player characters and monsters can also do things not covered by these actions. Many class features and other abilities provide additional action options, and you can improvise other actions. When you describe an action not detailed elsewhere in the rules, the Dungeon Master tells you whether that action is possible "
i.e. on-the-spot dm ruling or something like an in-house homebrew rule made by the DM.
Now, some argue that passive perception in the PHB has enough wording to say it is always on and counters a stealth check attempt to hide:
"Passive Perception is a score that reflects a creature’s general awareness of its surroundings. The DM uses this score when determining whether a creature notices something without consciously making a Wisdom (Perception) check."
Which... maybe... that was the intention fo that rule. But it is rather vague, the wording is a tad ambiguous, and the implications are weird*. But it would be something rule based.
(*) Weird, because passive perception is defined as "determing whether a creature notices something without consciously making a Wisdom (Perception) Check", but then goes on to explain the way to calculare Passive Perception is to pretend the creature consciously took the Search Action, spent at least a turn searching, and got a perfectly average roll.
The definition is you're not actively searching, but your score is as if you're actively searching and made an average roll. That's weird. Weirder still is that now, if you do make an active search, half the time you will roll worse than if you had spent your time doing nothing, or spent it doing something else entirely.
Interpreting the text to mean Passive Perception is always on and is the same as an average roll on an active Search Action Perception Check produces some really, really weird outcomes.
Typically at my table i use either an active Wisdom (Perception) check or Passive Perception instead. Not both acting as a minimum threshold or akin to 2 checks vs DC.
If i ask for an active Wisdom (Perception) check, it's so the result can expressly be above or below your Passive Perception score while i don't use this score for a given check.
While general awareness is usually always on unless your unaware of your surrounding, a Perception check is only needed when as DM i ask for it, and wether it's active or passive is at my discretion. One could then ask how could you often be less perceptive when actively searching then your general awareness? My answer is focused attention. It's one or the other i use though, as DM i usually uses an active check, unless i use a passive one instead.
Typically at my table i use either an active Wisdom (Perception) check or Passive Perception instead. Not both acting as a minimum threshold or akin to 2 checks vs DC.
The last half dozen or so DMs ive seen, rule PP is always on and is a floor. And players never ask to search during combat, so they never encounter situation where the active check is worse than passive.
Your approach is more nuanced, but most dms dont seem to be doing nuance, they seem to be following a mechanical application of the rules (always on, floor).
My solution is to clarify it IS always on and impose a -5/disadvantage passive perception penalty during combat, and martial classes get features that eventually overcome that penalty. So the nuance is built into thr rules and can be applied mechanically.
The way the rules work, the only thing you can do are things the rules say you can do.
First of all, this is false. If there had to be a rule for every possible thing that you could do, then the rulebook would be infinitely long.
First of all, no, this is exactly how the rules work. If the rules spell out all the ways a character can make an attack, and those rules say that your character can make 4 attacks, then you cant argue that there is no rule that PROHIBITS you from making a 5th attack therefore 5 attacks within the rules. That is the textbook example of an Argument from Ignorance logical falacy.
You are misunderstanding the point. There are tons of places in the rules where certain words or descriptions are used where the author makes an assumption that we are all on the same page. Otherwise, the books would be millions of pages long. For example, the books describe the rules for what happens when a creature falls. But what causes a creature to fall? Do the rules define that anywhere? If a creature steps off of the edge of a cliff, what happens? How do we know? Where is the rule for what happens when a creature steps off of the edge of a cliff? The DM might rule that this causes you to teleport to the next town. Or that they fly up into the air. Or that they float downwards extremely gently. But those things would be unexpected. Most players would reasonably expect that the consequence of a creature stepping off of the edge of a cliff would be similar to what happens in our real world. That's the basic framework of the rules -- by default, we can expect the physics of the environment to be similar to our real world. This doesn't have to be the case. The DM could create a world with moon-like gravity where people could jump 50 feet high and they never take falling damage because they never actually fall. But there should probably be some serious session 0 discussions about that. Not because the DM is actually changing any existing written rule, but because the rules are written with certain assumptions that the DM is now subverting.
The perception skill is like this also. The entire skill is all about how well your senses notice things in the environment. This includes our real-world senses such as vision and hearing. Do the rules have to define what the word "vision" means? Or "hearing"? No, there is an assumption that we all know what the author is talking about whenever they use phrases such as "you can see", etc. The word "find" is not actually used very often in the rules. So what? There are certain assumptions about what it actually means to find someone or something that do not have to be written. It involves perceiving that thing such that you now know its location when previously you did not. How do you perceive something? With your senses. There are also a few special features beyond your normal senses that can help you find creatures as well, but that's beyond the scope for now.
The game designers recognized from the beginning that your senses are at work all the time while you are conscious. They created a mechanic for passive checks in addition to active checks with Passive Perception being by far the most important since it is important to take this fact that your senses are always working into account when adjudicating anything that involves perception. Your brain is constantly receiving input and interpreting data that it receives from your senses all day long without you consciously doing anything. That's just part of being a living creature. The rules account for this.
but then goes on to explain the way to calculare Passive Perception is to pretend the creature consciously took the Search Action, spent at least a turn searching, and got a perfectly average roll.
The definition is you're not actively searching, but your score is as if you're actively searching and made an average roll. That's weird. Weirder still is that now, if you do make an active search, half the time you will roll worse than if you had spent your time doing nothing, or spent it doing something else entirely.
Interpreting the text to mean Passive Perception is always on and is the same as an average roll on an active Search Action Perception Check produces some really, really weird outcomes.
You seem to be weirdly stuck on this comparison between the formulae for active and passive checks. This is just how the designers decided to do it back in 2014 and this formula did not change in 2024. It's somewhat arbitrary but is also not a decision that was created in a vacuum. It involves game balance, desired probabilities for success, the interaction with other rules and so on. They could have originally created the formula to be 8 + modifiers. They could have originally created the formula to be 12 + modifiers. But they didn't. They chose to go with 10 + modifiers. And that decision is totally reasonable.
Saying that we are "pretending" to search and are getting an average roll is just not really grasping what these formulae are modeling. In the case of Perception, your senses are constantly perceiving things all of the time. But this isn't something that has any variance because you aren't really doing anything which could succeed or fail in the same manner that a D20 test models. Therefore, you have a set score for passive checks, and you might be slightly better or worse than someone else with a certain passive skill, but there is no variance in the outcome.
Now, once we determine that something is difficult enough to find that you didn't passively notice it, that automatically represents something that is already somewhat difficult to find. Because of this, it makes perfect sense that an active search will succeed less than half the time. But the only reason to spend this action to make this attempt in the first place is if you didn't already notice it yet. Constantly complaining that the passive check is the same as an average roll is missing the point of how it's meant to work.
For example, you always leave your car keys on the counter so that you can easily grab them when it's time to leave the house. One day, you walk into the room and you fail to notice the car keys -- they are not on the counter. So, your passive perception has already failed -- this means that it's not trivial to find the keys. So now the search for the keys begins. Will you find your car keys within the next 6 seconds? That's somewhat unlikely. You'll probably look in the wrong place. But it's certainly possible. It depends on whether you make an above average roll on your active Perception check when you begin your Search. If the keys are especially badly lost, you might have almost no chance of quickly finding them even if you do a really good job of searching. But again, the opposite will never be true because you would have already noticed them without searching if they were easy to find.
Honestly, some of your other threads on this topic probably belong in the Homebrew section of the forums since it sounds like you really want to change the formula for passive checks for some reason. But as for the premise of this thread -- determining whether or not Passive Perception is always on -- of course it is. Your eyes are always seeing, and your ears are always hearing unless something has explicitly happened to you such as having the blinded and/or deafened conditions.
Typically at my table i use either an active Wisdom (Perception) check or Passive Perception instead. Not both acting as a minimum threshold or akin to 2 checks vs DC.
The last half dozen or so DMs ive seen, rule PP is always on and is a floor. And players never ask to search during combat, so they never encounter situation where the active check is worse than passive.
Your approach is more nuanced, but most dms dont seem to be doing nuance, they seem to be following a mechanical application of the rules (always on, floor).
My solution is to clarify it IS always on and impose a -5/disadvantage passive perception penalty during combat, and martial classes get features that eventually overcome that penalty. So the nuance is built into thr rules and can be applied mechanically.
I have a different experience with DMs than you do. No rules say you can't take such action in combat. So you can definitely take the Search action in combat to try discern something that isn’t obvious and make Wisdom (Insight, Medicine, Perception, or Survival) check.
In such case i wouldn't use Passive Perception instead since you're consciously making a Wisdom (Perception) check as described in the Search action meaning DM don't risk "asking players to make Wisdom (Perception) checks for their characters tips them off that there's something they should be searching for, giving them a clue you'd rather they didn't have. In those circumstances, use characters' Passive Perception scores instead." since you're already doing just that actively and conciously.
The last half dozen or so DMs ive seen, rule PP is always on and is a floor. And players never ask to search during combat, so they never encounter situation where the active check is worse than passive.
People don't ask to search during combat because it's a waste of an action, changing passive perception won't alter that. If you want people to take the search action in combat, make the search action better.
"For example, the books describe the rules for what happens when a creature falls. But what causes a creature to fall?"
Yeah, you and i have polar opposite views of how the rules work on a fundamental level. So we"re probably never going to agree when the interpretatio of the rules comes down to something fundamental like this.
I am saying that even though the rules say you are hidden until someone "finds" you, and even though the rules define a thing called passive perception, neither thr rules for hiding nor the rules for passive perception state clearly exactly how, if at all, those two things interact. At which point, you get results from this poll where 25% of folks say passive perception is not always on, 75% says it is, and in the comments, folks are suggestijg their homebrew fixes to address the ambiguity by applying completely different solutions.
"But as for the premise of this thread -- determining whether or not Passive Perception is always on -- of course it is."
I would say the vast majority of dms think their interpretation of the rules is the correct interpretation, that of course theirs is the intended interpretation, and that its quite obvious that others are wrong.
Now imagine where 75% say one thing, and 25% say the opposite. Some might just tut-tut that and say one side is wrong.
Im mostly saying the rules, as written, suck.
"Because of this, it makes perfect sense that an active search will succeed less than half the time."
Perfect sense, eh? Well, thats the end of the discussion i suppose...
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Actually, 3/4 cover is explicitly mentioned as being good enough to potentially conceal your location by successfully hiding. As such, when the assassin who hid behind total cover (and has not yet been passively or actively found) comes to 3/4 cover to attack you, that attack does not reveal their location until the attack hits or misses as per the rules for Unseen Attackers and Targets combined with the rules for hiding. If the passive perception did not already detect this creature, it would not help them in that situation.
"that text does NOT say that that is the only way to find a creature,"
The way the rules work, the only thing you can do are things the rules say you can do. So, if the rules say you can misty step as a bonus action, then you can misty step as a bonus action. The rules will NEVER say that will be the only way to misty step, cause some subclass or feature might let you do it someway else.
BUT, unless therr is a rule somewhere that says you can misty step as a reaction, then all there is is the rule that says you can misty step as a bonus action, then bonus action is the only way you can do it.
The rules for Hide willl NEVER say that Search Action/Perception Check is the ONLY way to find someone hidden, but unless there is actual text rules that give another way, then there is no other way.
So unless there is a rule that says you can "find" someone who is hidden using your passive perception, then it isnt raw. It may be rai. But if its rai, then raw needs errata to clarify
My comment was in response to
"You can find a hidden creature behind Total Cover if you meet its Hide DC with a Wisdom (Perception) check or if the DM uses your Passive Perception instead and it's high enought to do so."
I.e. total cover.
To which i was agreeing that you could find someone behind total cover.
First of all, this is false. If there had to be a rule for every possible thing that you could do, then the rulebook would be infinitely long. Where is the rule that says that you can paraglide? Where is the rule that says that you can swing back and forth while grabbing a chandelier? Where is the rule that says that you can bake a loaf of bread? There are an infinite number of things that creatures can do that are not explicitly stated within the rules.
No, the 2024 rules made a deliberate effort to avoid repeating things in multiple places. There is no reason for the text of the Hide action to address this at all. The Hide action provides a mechanism for determining how to adjudicate a Search action to find a hidden creature. There are already rules elsewhere that establish that Passive Perception is used to notice creatures and objects when not actively searching. So, setting the DC explicitly for the Search action also implicitly sets the DC for Passive Perception, by rule. This is because the DC is a property of the thing being found, not a property of the method of finding it. Any time it is possible to actively search for something you might also discover it passively. That's RAW.
A similar issue arises when people like to claim that taking the Hide action "only" gives you the Invisible condition. This is false. It's just that the other rules and mechanics for hidden creatures are located elsewhere -- therefore, they do not need to be written into the text for the Hide action. The Hide action establishes that you become a hidden creature. In the rules for Unseen Attackers and Targets we learn that the location of a hidden creature is unknown specifically because they are both unseen and unheard. Therefore, the act of becoming hidden means that you become both unseen and unheard. An additional consequence is that you also gain the invisible condition -- that detail is not given anywhere else, so it has to exist within the text for the Hide action. In the 2024 rules, this sort of thing happens all over the place because the authors tried very hard to save word count by avoiding redundancy.
Sometimes your DM will determine whether your character notices something without asking you to make a Wisdom (Perception) check; the DM uses your Passive Perception instead.
Not always.
First of all, no, this is exactly how the rules work. If the rules spell out all the ways a character can make an attack, and those rules say that your character can make 4 attacks, then you cant argue that there is no rule that PROHIBITS you from making a 5th attack therefore 5 attacks within the rules. That is the textbook example of an Argument from Ignorance logical falacy. "The fallacy is committed when one asserts that a proposition is true because it has not yet been proven false"
https://en.wikipedia.org/wiki/Argument_from_ignorance
https://www.dndbeyond.com/sources/dnd/phb-2024/playing-the-game#Actions
"Player characters and monsters can also do things not covered by these actions. Many class features and other abilities provide additional action options, and you can improvise other actions. When you describe an action not detailed elsewhere in the rules, the Dungeon Master tells you whether that action is possible "
i.e. on-the-spot dm ruling or something like an in-house homebrew rule made by the DM.
Now, some argue that passive perception in the PHB has enough wording to say it is always on and counters a stealth check attempt to hide:
https://www.dndbeyond.com/sources/dnd/phb-2024/rules-glossary#PassivePerception
"Passive Perception is a score that reflects a creature’s general awareness of its surroundings. The DM uses this score when determining whether a creature notices something without consciously making a Wisdom (Perception) check."
Which... maybe... that was the intention fo that rule. But it is rather vague, the wording is a tad ambiguous, and the implications are weird*. But it would be something rule based.
(*) Weird, because passive perception is defined as "determing whether a creature notices something without consciously making a Wisdom (Perception) Check", but then goes on to explain the way to calculare Passive Perception is to pretend the creature consciously took the Search Action, spent at least a turn searching, and got a perfectly average roll.
The definition is you're not actively searching, but your score is as if you're actively searching and made an average roll. That's weird. Weirder still is that now, if you do make an active search, half the time you will roll worse than if you had spent your time doing nothing, or spent it doing something else entirely.
Interpreting the text to mean Passive Perception is always on and is the same as an average roll on an active Search Action Perception Check produces some really, really weird outcomes.
Typically at my table i use either an active Wisdom (Perception) check or Passive Perception instead. Not both acting as a minimum threshold or akin to 2 checks vs DC.
If i ask for an active Wisdom (Perception) check, it's so the result can expressly be above or below your Passive Perception score while i don't use this score for a given check.
While general awareness is usually always on unless your unaware of your surrounding, a Perception check is only needed when as DM i ask for it, and wether it's active or passive is at my discretion. One could then ask how could you often be less perceptive when actively searching then your general awareness? My answer is focused attention. It's one or the other i use though, as DM i usually uses an active check, unless i use a passive one instead.
The last half dozen or so DMs ive seen, rule PP is always on and is a floor. And players never ask to search during combat, so they never encounter situation where the active check is worse than passive.
Your approach is more nuanced, but most dms dont seem to be doing nuance, they seem to be following a mechanical application of the rules (always on, floor).
My solution is to clarify it IS always on and impose a -5/disadvantage passive perception penalty during combat, and martial classes get features that eventually overcome that penalty. So the nuance is built into thr rules and can be applied mechanically.
You are misunderstanding the point. There are tons of places in the rules where certain words or descriptions are used where the author makes an assumption that we are all on the same page. Otherwise, the books would be millions of pages long. For example, the books describe the rules for what happens when a creature falls. But what causes a creature to fall? Do the rules define that anywhere? If a creature steps off of the edge of a cliff, what happens? How do we know? Where is the rule for what happens when a creature steps off of the edge of a cliff? The DM might rule that this causes you to teleport to the next town. Or that they fly up into the air. Or that they float downwards extremely gently. But those things would be unexpected. Most players would reasonably expect that the consequence of a creature stepping off of the edge of a cliff would be similar to what happens in our real world. That's the basic framework of the rules -- by default, we can expect the physics of the environment to be similar to our real world. This doesn't have to be the case. The DM could create a world with moon-like gravity where people could jump 50 feet high and they never take falling damage because they never actually fall. But there should probably be some serious session 0 discussions about that. Not because the DM is actually changing any existing written rule, but because the rules are written with certain assumptions that the DM is now subverting.
The perception skill is like this also. The entire skill is all about how well your senses notice things in the environment. This includes our real-world senses such as vision and hearing. Do the rules have to define what the word "vision" means? Or "hearing"? No, there is an assumption that we all know what the author is talking about whenever they use phrases such as "you can see", etc. The word "find" is not actually used very often in the rules. So what? There are certain assumptions about what it actually means to find someone or something that do not have to be written. It involves perceiving that thing such that you now know its location when previously you did not. How do you perceive something? With your senses. There are also a few special features beyond your normal senses that can help you find creatures as well, but that's beyond the scope for now.
The game designers recognized from the beginning that your senses are at work all the time while you are conscious. They created a mechanic for passive checks in addition to active checks with Passive Perception being by far the most important since it is important to take this fact that your senses are always working into account when adjudicating anything that involves perception. Your brain is constantly receiving input and interpreting data that it receives from your senses all day long without you consciously doing anything. That's just part of being a living creature. The rules account for this.
You seem to be weirdly stuck on this comparison between the formulae for active and passive checks. This is just how the designers decided to do it back in 2014 and this formula did not change in 2024. It's somewhat arbitrary but is also not a decision that was created in a vacuum. It involves game balance, desired probabilities for success, the interaction with other rules and so on. They could have originally created the formula to be 8 + modifiers. They could have originally created the formula to be 12 + modifiers. But they didn't. They chose to go with 10 + modifiers. And that decision is totally reasonable.
Saying that we are "pretending" to search and are getting an average roll is just not really grasping what these formulae are modeling. In the case of Perception, your senses are constantly perceiving things all of the time. But this isn't something that has any variance because you aren't really doing anything which could succeed or fail in the same manner that a D20 test models. Therefore, you have a set score for passive checks, and you might be slightly better or worse than someone else with a certain passive skill, but there is no variance in the outcome.
Now, once we determine that something is difficult enough to find that you didn't passively notice it, that automatically represents something that is already somewhat difficult to find. Because of this, it makes perfect sense that an active search will succeed less than half the time. But the only reason to spend this action to make this attempt in the first place is if you didn't already notice it yet. Constantly complaining that the passive check is the same as an average roll is missing the point of how it's meant to work.
For example, you always leave your car keys on the counter so that you can easily grab them when it's time to leave the house. One day, you walk into the room and you fail to notice the car keys -- they are not on the counter. So, your passive perception has already failed -- this means that it's not trivial to find the keys. So now the search for the keys begins. Will you find your car keys within the next 6 seconds? That's somewhat unlikely. You'll probably look in the wrong place. But it's certainly possible. It depends on whether you make an above average roll on your active Perception check when you begin your Search. If the keys are especially badly lost, you might have almost no chance of quickly finding them even if you do a really good job of searching. But again, the opposite will never be true because you would have already noticed them without searching if they were easy to find.
Honestly, some of your other threads on this topic probably belong in the Homebrew section of the forums since it sounds like you really want to change the formula for passive checks for some reason. But as for the premise of this thread -- determining whether or not Passive Perception is always on -- of course it is. Your eyes are always seeing, and your ears are always hearing unless something has explicitly happened to you such as having the blinded and/or deafened conditions.
I have a different experience with DMs than you do. No rules say you can't take such action in combat. So you can definitely take the Search action in combat to try discern something that isn’t obvious and make Wisdom (Insight, Medicine, Perception, or Survival) check.
In such case i wouldn't use Passive Perception instead since you're consciously making a Wisdom (Perception) check as described in the Search action meaning DM don't risk "asking players to make Wisdom (Perception) checks for their characters tips them off that there's something they should be searching for, giving them a clue you'd rather they didn't have. In those circumstances, use characters' Passive Perception scores instead." since you're already doing just that actively and conciously.
People don't ask to search during combat because it's a waste of an action, changing passive perception won't alter that. If you want people to take the search action in combat, make the search action better.
"For example, the books describe the rules for what happens when a creature falls. But what causes a creature to fall?"
Yeah, you and i have polar opposite views of how the rules work on a fundamental level. So we"re probably never going to agree when the interpretatio of the rules comes down to something fundamental like this.
I am saying that even though the rules say you are hidden until someone "finds" you, and even though the rules define a thing called passive perception, neither thr rules for hiding nor the rules for passive perception state clearly exactly how, if at all, those two things interact. At which point, you get results from this poll where 25% of folks say passive perception is not always on, 75% says it is, and in the comments, folks are suggestijg their homebrew fixes to address the ambiguity by applying completely different solutions.
"But as for the premise of this thread -- determining whether or not Passive Perception is always on -- of course it is."
I would say the vast majority of dms think their interpretation of the rules is the correct interpretation, that of course theirs is the intended interpretation, and that its quite obvious that others are wrong.
Now imagine where 75% say one thing, and 25% say the opposite. Some might just tut-tut that and say one side is wrong.
Im mostly saying the rules, as written, suck.
"Because of this, it makes perfect sense that an active search will succeed less than half the time."
Perfect sense, eh? Well, thats the end of the discussion i suppose...