# XVII explained — Philosophical Works

> Chapter companion for Philosophical Works by René Descartes.

## What happens

This chapter argues that the objective perfection in an idea must be caused by something with at least as much formal or eminent perfection. Using the analogy of a complex machine, Descartes explains that the skill displayed in the idea must exist in its cause, whether that cause is an external inventor or the mind's own genius.

## Themes in this chapter

### Existence of God

The principle that the cause must contain as much perfection as the effect is foundational to Descartes' argument for God's existence from the idea of a perfect being.

### Reason and Method

Descartes employs a methodical analogy—the idea of a machine—to illustrate a general causal principle about ideas.

## Character check-ins

### Narrator

The narrator reflects on the relationship between the perfection of ideas and their causes.

## Key lines

> the greater objective (representative) perfection there is in our idea of a thing, the greater also must be the perfection of its cause.

The more perfection an idea represents, the more perfection its cause must possess.

_This states the core causal principle that Descartes will apply to the idea of God._

> all the ingenuity which is contained in the idea objectively only, or as it were in a picture, must exist at least in its first and chief cause, whatever that may be, not only objectively or representatively, but in truth formally or eminently.

All the skill depicted in an idea must actually exist in its ultimate cause, either in the same form or in a higher form.

_Descartes uses the machine analogy to clarify that the cause must have the perfection either formally (in the same way) or eminently (in a higher way)._

## Links

- HTML: https://www.betterreads.online/discover/philosophical_works_se/chapters/xvii
- Book: https://www.betterreads.online/discover/philosophical_works_se
- All chapters: https://www.betterreads.online/discover/philosophical_works_se/chapters