前苏格拉底哲学是西方哲学中，在苏格拉底之前的哲学流派。我们有时候很难找到这个时期的哲学家们用来支持他们各自论点的原话，尽管他们写出了十分重要的文本，但却都没有保留下来。我们现在所能看到的思想都是摘录自后来的哲学家、历史学家或者一些偶然发现的残本中。

从那个时代开始，哲学家们反对过去对世界的神秘主义解释，他们试图通过理性进行重新诠释。他们追问诸如此类的问题：

他们所提出的问题和悖论成为了后代研究数学、科学和哲学的基本问题。尽管这个时期的哲学家所作出的宇宙论已经被基于现代科学的观点所取代，后代哲学家也不同意他们对其他问题所作出的答案，但这些问题的重要性是公认的。

Pre-Socratic philosophy is Greek ancient philosophy before Socrates (and includes schools contemporary to Socrates that were not influenced by him). In Classical antiquity, the Presocratic philosophers were called physiologoi (Greek:φυσιόλογοι; in English, physical or natural philosophers). Aristotle called them physikoi ("physicists", after physis, "nature") because they sought natural explanations for phenomena, as opposed to the earlier theologoi (theologians), whose philosophical basis was supernatural. Diogenes Laërtius divides the physiologoi into two groups, Ionian and Italiote, led by Anaximander and Pythagoras, respectively.