Towards Descartes’ Scientific Method: a posteriori Evidence and the Rhetoric of Les Météores

I argue that Descartes uses his method as evidence in the Discours and Les Météores. I begin by establishing there is a single method in Descartes’ works, using his meteorology as a case study. First, I hold that the method of the Regulae is best explained by two examples: one scientific, his proof of the anaclastic curve (1626), and one metaphysical, his question of the essence and scope of human knowledge (1628). Based on this account, I suggest that the form of his early metaphysics (not its content) is similar to the method of doubt of the Meditationes. Second, I argue that Descartes’ explanation of the cause of parhelia (1629) likewise contains a formulation of this procedure. I provide a novel reading of Les Météores, where, following Descartes’ guidance in the Discours and Correspondance, I interpret his meteorology by reasoning from effects to causes, in this case, from Christoph Scheiner’s 1626 observation of parhelia to his meteorological foundation. This backwards orientation to Les Météores, I argue, reveals an instance of Descartes’ scientific method. I conclude with remarks on Descartes’ concept of evidentia, in which I explain how he incorporates a posteriori evidence and an apparent hypothetical foundation into his rationalist epistemology where he uses his method as evidence for his claims

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability