Criticisms that Tufte and others have leveled against PowerPoint are not insurmountable defects of the programs themselves. These defects are generally due to an orientation, shared by program designers and users alike, and toward images rather than diagrams, toward perceptual decoration and object indication rather than toward visually mediated, iconic representations Of verbal information. Using Peirce's theories of visual rhetoric, we show that improvements in visual communication generally - and PowerPoint slides in particular - depend on shifting our orientation away from image-driven thinking and toward diagrammatic modes of presentation.