Though Descartes is today especially remembered as a philosopher, he himself thought of his scientific work as primary. He made major contributions to optics and to mathematics (we still speak of "cartesian coordinates"), and he developed a new physics. Cartesian physics, forgotten today, has various features.
1. There is no action at a distance. The only way in which one body can act upon another is through contact.
2. There is no such thing as empty space ("void").
3. Matter consists of very small particles some of which are bigger, and others are more like dust, created by the bigger ones being worn away.
4. Weight or mass is not an intrinsic property of material particles.
The physics of Descartes was an explanatory framework which was theoretically powerful, at least potentially, but which did not give any way of making specific predictions.
Cartesian physicists conflicted with the followers of Newton because he reintroduced "action at a distance", which they regarded as a superstition. Newton's response was simply that the inverse square law for gravitation worked, and that he was not concerned to make hypotheses to explain this. ("Hypotheses non fingo" - "I do not make hypotheses".)