Note that a true Pathology is one that is fundamental to the game, built into the game design. As such, under the Situation Model, a Pathology only ever arises from things born of either the Game Input or the Results of some prior input.
A Faux Pathology is not a true Pathology. Because analysing a game's design is virtually impossible without considering some player's involvement, it is possible for a player to consider something a Pathology that isn't. For example, it might simply be a puzzle that the player lacks sufficient Reason to solve, but feels to that player like there is a critical piece of Knowledge missing. The line between a Faux Pathology and a real Pathology is somewhat blury.
A Critical Pathology is a Pathology that causes the game to no longer be functional at all. A non-critical Pathology may allow the game to still be interesting or fullfill its goal; a Cricial Pathology does not. Note that the game can still be progressable, but the intent of the game design is drastically damaged if not destroyed. Typically, this happens in one of the following ways:
A Knowledge Pathology is a Pathology in a game based on the Knowledge domain of the Situation Model. The game's design provides certain expectations about the player's Knowledge base, for later Situations will test those expectations. A Pathology develops if the player's body of Knowledge differs significantly from what the game expects the player to have at that particular Situation.
There are two forms of this Pathology. A Negative Knowledge Pathology is merely when the game has not provided the player with a certain piece of Knowledge. Because the player's Comprehension is also a factor, it can inspire a Faux Pathology whereby the player simply lacks the comprehension necessary to deduce the Knowledge. The true form of the Pathology is when the game does not provide any Result that has some form of logical consequence that leads from that Result to Knowledge.
A slightly alternate form of this Pathology is when the game provides a result, but it requires a Game Input that the player is not likely to provide. This is often due to a Knowledge Pathology that has already occurred, however, and is rarely encountered in the absense of other errors.
The second form of Knowledge Pathology is the False Knowledge Pathology. False Knowledge happens as a true Pathology when the game expects the player to reason one thing, but given what the player knows, some other thing that is actually untrue seems more reasonable based on that Result. The Faux Pathology analog of this is when one's Comprehension is simply erronous, or otherwise different from what the game expects, and the player's logical deduction came to the wrong conclusion.