1. One or more non-transitory computer-readable media storing computer-executable instructions that, when executed on one or more processors, cause the one or more processors of a virtual assistant service to perform acts comprising: generating data for a conversation graphical user interface (GUI) that represents a virtual assistant; causing display of the conversation GUI via a computing device to enable a conversation between the virtual assistant and a user of the computing device; receiving user input that is provided via the conversation GUI, the user input comprising one of audio input, keypad input, or touch input; parsing the user input with a natural language processing system that employs a language model; determining, with the natural language processing system, a response based at least in part on (i) the parsed user input and (ii) at least one of content of a service provider, content of the virtual assistant service, or content of the computing device of the user; identifying an assumption that is used to determine the response, the assumption comprising at least one of the language model that is employed by the natural language processing system, a profile for the user, or a learned behavior of the user; causing display of a dialog representation in the conversation GUI for the user input; causing display of a dialog representation in the conversation GUI for the response; causing display of the assumption in the conversation GUI; enabling the user to interact with the conversation GUI to modify the assumption; receiving a modification to the assumption; determining a revised response based at least in part on the modification to the assumption; and causing display of the revised response in the conversation GUI.