Problem: Critics point out that Moses could not have written all of the Pentateuch, because the end of Deuteronomy (ch. 34) records his death.
Solution: This is not a new objection. Obviously, readers of the Bible have made this observation for millennia. Proponents of Mosaic authorship have always assumed that a later author added this final chapter after Moses died. Because the book of Joshua is a clear continuation of the story, it is argued that Joshua probably wrote Moses’ obituary. Likewise, the prophet after Joshua probably wrote his obituary. Admitting that the last chapter was a later addition is different than saying that all the chapters were later additions or redactions. This objection really throws the baby out with the bathwater. We cannot judge the theory of Mosaic authorship based on the last chapter of the Pentateuch. Instead, we need to base our judgment on all of the collective chapters combined. For more on this subject, see “Authorship of the Pentateuch.”