In arts, especially visual arts, humans have perfected their skills to create distinctive experiences by combining a multifaceted interplay between the substance and design of images. Innate mechanisms of this process have remained unknown so far, and no artificial system with similar capabilities exists yet. However, the increasing prevalence of artificial intelligence in arts has drastically changed what seems to be the underlying constants, such as artistic creativity and authorship of artworks. This phenomenon becomes even more commonplace in the post-truth era as facts become fiction in competing versions. Although art has not always been searching for truths, artificial intelligence powered by generative adversarial networks puts the entire concept of art in a much larger context. In such a context, this descriptive-qualitative study based on literature review, which aims to discuss the impacts of artificial intelligence on photography and painting in the post-truth era and the issues of creativity and authorship, first explains the concept of generative adversarial networks and then examines a sample of their uses in photography and painting with concrete examples. Later, the study discusses the effects of artificial intelligence driven by generative adversarial networks on the art market and analyzes the concept of creativity and the issue of authorship because of those impacts in the context of works of art. Finally, the notion of post-truth is explained, and what the advent of artificial intelligence is likely to mean for art in the future within the framework of post-truth is questioned. Results show that the lines between art's expressive and demonstrative functions are beginning to blur, while the border between fiction and reality is becoming increasingly blurred. AI powered by GANs re-contextualizes the meaning of the truth in artistic endeavors as it happens whenever a novel medium or technology appears and is increasingly adopted by more people at various paces and rates.