Problem: For each of the following short arguments; (a) say whether the argument is deductively valid or invalid. Then (b) if you think the argument is invalid, explain why the argument is invalid. If you think the argument is valid, then represent the logical form of the argument, making sure you indicate what your schematic letters stand for. All functionally extinct species are unable to reproduce enough to sustain their population. Koalas can reproduce enough to sustain their population. So koalas are not a functionally extinct species.