Science is among the major accomplishments of the human race. It is our most reliable source of knowledge about the world. But what, if any, are the limits of science? Are there questions that will forever elude our best scientific efforts? According to modern science itself, after all, the human brain is the product of a long and capricious process of biological evolution. Do we have any reason to suspect that science will penetrate the deepest mysteries of the universe? Epistemic pessimists, by our humble origins, have argued for cognitive closure: some truths about the universe will forever remain beyond our ken. Our paltry are just not up to the task. project will explore whether this pessimism is warranted. First, I will develop a conceptual toolbox for parsing different forms and modalities of cognitive closure. If science ever comes to a halt, will this feel like slamming into a brick wall, or slowly getting bogged down in a swamp? Many parts of modern science are intuitively perplexing. Second, I will explore different strategies for extending or scaffolding our cognitive endowments, thereby overcoming our natural limitations. Finally, I will the relationship between the thesis of cognitive closure and the problem of scientism. Are we overly confident in the epistemic powers and universal applicability of science and its methods? Is some epistemic humility called for, in view of our humble origins?