The point is that if the transformation that Stuart uses were applied to a single agent, it would convert a coherent utility function into an incoherent one; therefore it cannot demonstrate anything about the incoherence of combined utility functions. It is too general—in fact, it is a Fully General Counterargument to the existence of utility functions with more than one input. It could well be the case that independent agents cannot have a coherent combined utility function, but this argument does not demonstrate it unless you also wish to assert that single-agent utility functions cannot consist of linear additions of sub-utilities.
in fact, it is a Fully General Counterargument to the existence of utility functions with more than one input
No, it’s not, because it is not even talking about a utility function with more than one input. It is talking about two completely seperate utility functions. A single utility function with multiple inputs has to include a scaling between the inputs and therefore is not described by Stuart’s argument, which exploits the lack of such scaling between two seperate utility functions.
The point is that if the transformation that Stuart uses were applied to a single agent, it would convert a coherent utility function into an incoherent one; therefore it cannot demonstrate anything about the incoherence of combined utility functions. It is too general—in fact, it is a Fully General Counterargument to the existence of utility functions with more than one input. It could well be the case that independent agents cannot have a coherent combined utility function, but this argument does not demonstrate it unless you also wish to assert that single-agent utility functions cannot consist of linear additions of sub-utilities.
No, it’s not, because it is not even talking about a utility function with more than one input. It is talking about two completely seperate utility functions. A single utility function with multiple inputs has to include a scaling between the inputs and therefore is not described by Stuart’s argument, which exploits the lack of such scaling between two seperate utility functions.