Abstract

Axiom 4 of the Ethics of Spinoza runs:The knowledge (cognitio) of an effect depends upon and involves the knowledge of the cause.Since this is in the ancestry of some of Spinoza’s most important and characteristic claims, a clarification of its meaning would be highly desirable (in the literature it is left unhelpfully vague.) I argue that A4 is a causal likeness principle, according to which causal relationships always feature a property which in some sense is “passed” from the cause to the effect. This interpretation provides a key to understanding some darker passages.