Is the Inquisitive rogue's Ear for Deceit feature made useless by a character's Passive Insight score?

Question

The Inquisitive rogue's Ear for Deceit feature (XGtE, p. 45) says:

When you choose this archetype at 3rd level, you develop a talent for picking out lies. Whenever you make a Wisdom (Insight) check to determine whether a creature is lying, treat a roll of 7 or lower on the d20 as an 8.

Passive Insight is 10 + Wisdom modifier (+ proficiency bonus, if proficient), which is better than 8 + the same modifiers from the Ear for Deceit feature. I've seen stated before by Mike Mearls on Twitter that passive scores were meant to be treated as minimum scores:

A check requires an action. So, PC enters room. Passive notices anything there. Check needed for anything that has DC above passive.

Does that mean that this ability actually has no use? At least nothing that I can really make out... Unless for some reason your passive Insight isn't applicable.

Answer 1

Passive checks are different from active ones

A passive check is a special kind of ability check that doesn’t involve any die rolls. Such a check can represent the average result for a task done repeatedly, such as searching for secret doors over and over again, or can be used when the DM wants to secretly determine whether the characters succeed at something without rolling dice, such as noticing a hidden monster. (PHB 175)

As per the rule on Passive checks, if the enemy is using their passive Deception it's likely you would use your passive Insight.

The idea behind the ability is not to modify how well you passively catch liars but how well you actively catch them. Generally when someone lies to you they make a deception check vs your insight. In this opposed roll situation you have a 40% chance of a better or equal result (if you have the same bonus to deception/insight).

Usefulness will depend on your DM

As with a lot of non-combat abilities in D&D their usefulness is determined by how often your DM calls for them. If you DM only ever uses passive checks for lying/insight then this ability is generally worthless. If you find your DM doing this let them know that it feels like their making a class feature of yours feel like it was a waste.

Answer 2

Mike Mearls is simply wrong.

Read the book, play the game, learn from your experiences, ignore the tweets.

He's wrong when he says that an ability check requires an action. It's unclear whether he means an action in terms of the turn structure, or an action in the informal sense of putting forth effort to do something, but either way there are obvious counterexamples:

• Initiative is an ability check to determine how quickly you notice a situation, and is prior to anyone taking any action at all.
• A Grapple requires an opposed Athletics check, meaning both the attacker and the defender make checks; it replaces a single attack by the attacker, and costs the defender no action/reaction at all.
• The examples in the rules for Acrobatics checks include "stay upright on a rocking ship's deck". You're literally making a check to just stand there.
• Talking generally does not require an action, and may result in a Persuasion or Deception or other check to determine what effect your words have. This may (as in your situation here) be an opposed check, so even the character who's not talking has to make an ability check.

He's also wrong about automatically succeeding when a DC is below your passive skill. As described in the PHB, passive skill doesn't apply to normal ability checks at all. It applies to passive checks, which are a different kind of check made under different circumstances.

In general, if you are allowed to roll for a check, you don't also get to apply your passive skill to that check.

Answer 3

The interpretation by Mike Mearls is on the liberal side of RAW

From the Player's Handbook page 175 (emphasis added):

Passive Checks

A passive check is a special kind of ability check that doesn't involve any die rolls. Such a check can represent the average result for a task done repeatedly, such as searching for secret doors over and over again, or can be used when the DM wants to secretly determine whether the characters succeed at something without rolling dice, such as noticing a hidden monster.

Passive checks are not required to be used by the DM, and in fact some DMs may never use them! Judging from the the tweet by Mike Mearls, it seems that he uses them a lot, while some DMs I know usually only use Passive Perception or don't use passive checks at all. I like to use passive skills to give hints to specific players, which generally prompts them to make an active check.

The bottom line is that the usefulness of the Ear for Deceit feature will depend on your DM. If you feel that it's being unfairly ignored, talk to them about it.

Answer 4

First of all, as pointed out by others: Mike Mearl's interpretation of the rules is extremely liberal. The rules for passive checks follows the following rule:

A passive check... can represent the average result for a task done repeatedly, such as searching for secret doors over and over again, or can be used when the DM wants to secretly determine whether the characters succeed at something without rolling dice, such as noticing a hidden monster.

Unfortunately the paragraph is vague, when it 'can' represent, and 'can' be used don't confirm what it does represent, nor does it confirm when it can be used, it also doesn't weed out what it does represent, nor does it weed out when it situations where it cannot be used, in this way these are almost merely suggestions. Several conclusions and implications can be made, however!

• First, an implication: A DM can say that throughout the conversation the character is constantly trying to gain insight into what the intentions of the person he is conversing with are. As such, he can use a passive check which represents the average of making the check over an over.
• Second, a conclusion: The word 'or' directly indicates that neither the proposition on what passive checks represent, nor the the proposed usage of them, are required. This would imply that a passive check does not need to be used as a representation of continuous action.

My final conlcusion is this: A RaW reading of the rules allows 5e to be played in a way that passive checks are always in use (so long as you have time to perform the task repeatedly), but a reading of the rules RaW also allows you to determine that passive checks are not always in use. In the end it is up to the DM, but there are rules out there there that (such as ear of deceit) that implies passive checks should not always be used. To begin with, if an ability exists it shouldn't be worthless! If your DM plays things out in a way that a PCs feature is useless, he isn't doing things right.

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Finally I want to bring something up that hasn't been brought up, note that this is an equivocation of the previous way I used 'can represent the average result.' If the passive perception represents the mathematic average for a task done repeatedly, the mathematic average for the task done repeatedly would actually more properly be 10.5 + all modifiers that normally apply to the check. 5e rounds down on rational numbers though, so 10 is used. In the case of eye of deceit, 10.5 isn't the average that you will roll on a 20 sided die though. 11.9 technically is. I would personally round this bonus up because of a statistical phenomenon that occurs which makes eye of deceit potentially lose a lot of value when its effects on a 20 sided die roll are converted to an average bonus.