Locke owed much to his precedent and contemporary natural philosophers for the formation of his philosophical thought. His debt to Descartes, Boyle and Sydenham has been widely recognized. This paper argues that the chief influence on Locke's empiricism is from his medical mentor, Sydenham, and examines the origin of Locke's “Historical, plain Method”. Locke's early medical manuscripts and Drafts for the Essay, written while Locke was working with Sydenham, reveal that he was under strong influence of Sydenham's strict empiricism. However, Locke took a more moderate position in Essay and was aware of the uses of probable hypotheses in natural philosophy.
Smith proposed an equitable maxim requiring that our moral sentiments of merit and demerit should be based on the expected consequence of the action. But in practice, these sentiments vary with the actual consequence. Smith called this ‘irregularity of moral sentiment (hereafter IS)’. In this paper I would like to suggest Smith's possible explanation and justification of IS in reference to the contemporary debates on moral luck and responsibility. Smith can explain IS in terms of epistemic value of consequence of action. Smith's justifications of IS are based on the practice of atonement and the agent's guilt feeling, which admit of both consequential and non-consequential interpretations.