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The Limits of Knowledge (Scepticism)

3. Descartes' Response to the Sceptical Challenge

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In this module, we look at Descartes’ response to his sceptical challenge, focusing in particular on (i) how cogito ergo sum functions as the first step in the attainability of some kind of knowledge (ii) Descartes’ notion of clear and distinct ideas (iii) the importance of discerning the existence of God, and the possibility of whether God is a deceiver (iv) why the idea of God must be innate and endowed by God, according to Descartes (v) why God, a supremely perfect being, cannot be a deceiver according to Descartes (vi) first-order ideas and second-order ideas of external world objects.


In this course, Dr Ema Sullivan-Bissett (University of Birmingham) explores the limits of knowledge (scepticism). In the first module, we contrast normal incredulity to philosophical scepticism, and examine various ways to remove grounds for doubt. In the second module, we come to look at how Descartes arrives at his three stages of doubt, laying the groundwork for the sceptical challenge. In the third module, we turn to Descartes’ response to the sceptical challenge, before looking at Locke’s response in the fourth module. In the fifth module, we examine Berkely’s idealism in response to the sceptical challenge. In the sixth module, we evaluate G.E. Moore’s proof of an external world. Finally, in the seventh module, we consider whether a possible response to scepticism can be found in contextualism.


Dr Ema Sullivan-Bisset is a reader in philosophy at the University of Birmingham. Her research interests are in the philosophy of mind and psychology. Her recent publications include Better to return whence we came (2022) and Debunking doxastic transparency (2022).

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APA style

Sullivan-Bissett, E. (2022, May 16). The Limits of Knowledge (Scepticism) - Descartes' Response to the Sceptical Challenge [Video]. MASSOLIT.

MLA style

Sullivan-Bissett, Ema . "The Limits of Knowledge (Scepticism) – Descartes' Response to the Sceptical Challenge." MASSOLIT, uploaded by MASSOLIT, 23 May 2022,

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