Pierre-Paul Grassé quotes
When we consider a human work, we believe we know where the "intelligence" which fashioned it comes from; but when a living being is concerned, no one knows or ever knew, neither Darwin nor Epicurus, neither Leibniz nor Aristotle, neither Einstein nor Parmenides. An act of faith is necessary to make us adopt one hypothesis rather than another. Science, which does not accept any credo, or in any case should not, acknowledges its ignorance, its inability to solve this problem which, we are certain, exists and has reality.
Pierre-Paul Grassé
The immanent purpose is an intrinsic property of living beings, without it, they would not exist. Consider the autonomous function units and their components: organs, tissues, isolated cells, as well as other properties such as nutrition, body defense, growth, reproduction, to which they are subject at the end. When it comes to these properties, biologists do not argue; but if you pronounce the word purpose, there is a public outcry. Probably because they do not distinguish the purpose of fact or immanent, the trascendental purpose. Of the latter, the biologist has little or nothing to say; it is a matter of metaphysics.
Pierre-Paul Grassé