Many behaviors which initially appear incongruent reveal themselves, on closer examination, not to be. Often, such discoveries are made possible by differentiating the circumstances surrounding the behaviors in question.
For example, one may observe the unconcern with which people converse in crowded places and wonder at why a lone stranger approaching on a hiking trail has the power to cease the chatter between two friends for as long as the friends deem the stranger within the auditory bounds of their privacy. What these two circumstances share serves as evidence supporting the notion that the behaviors are indefensibly inconsistent, whereas the differences between the circumstances serve to justify the disparate behaviors. Both circumstances involve collocutors in the presence of strangers, yet the density of strangers and the duration of their presence are parameters whose values differ greatly between a hiking trail and a crowded restaurant. Therefore, the claim of inconsistent behavior can be rendered null by declaring that the behavior chosen is a decision made according to whether the parameter values have exceeded a personal threshold.
It’s tempting to perceive the defeat of the incongruent behavior hypothesis as proof that the dual behavior modes are rational, but I wouldn’t go that far. Establishing that each behavior mode is associated with a particular class of circumstance isn’t equivalent to demonstrating that the behaviors have a rational basis. If two people are comfortable talking to one another while standing next to a stranger at an outdoor concert, there’s no privacy-related reason that they should be motivated to pause their conversation while crossing paths with someone on a mountain. However, there may be other motivations to pause the conversation–to greet in passing the person with whom the collocutors are crossing paths, for example. After all, when encountering another amid the less-traveled outdoors, one is strongly compelled, by a perhaps innate impulse, to at least acknowledge their presence.
In sum, anyone suspected of incongruent behavior is likely to happily explain why their behavior should not be characterized as such, and, if they can differentiate the associated circumstances, they’ll likely be right. Through elimination of the ‘incongruent’ adjective, they point to what is probably a more accurate label: ‘irrational’, and, in doing so, they affirm that they are human.