Chapter 3

The simplicity of the soul shown from the properties with which the soul is furnished

432. I have already set out the direct proof drawn from intimate consciousness. The following demonstration of the soul's simplicity can be drawn from its properties.

We begin from the definition of the soul: 'The soul is the principle of feeling and understanding.' This definition shows immediately that the soul is simple. In other words, it shows that multiplicity, continuous extension and materiality have no place in the concept of soul.

But every ens has its own properties, through which it is determined and distinct from every other. The properties which specify an ens cannot be communicated to any other not pertaining to that species. If it were possible, the species of things would be confused. In fact, they are inconfusable because their distinction is founded in the intrinsic order of ens, which is eternal and immutable.(186) It is sufficient to prove, therefore, that the concept of soul and that of multiplicity, extension and materiality are specifically different to show that they are mutually exclusive, and that the soul is neither multiple nor extended nor material.

433. Multiplicity, I maintain is opposed to every real substance because no real substance is possible unless it is one. Continuous extension, as we have seen, is found only in what is felt and in what is sensiferous. But the soul is the sentient principle, and 'sentient' is specifically different from the concept of what is felt and what is sensiferous. The soul, therefore, has no extension.

In the same way, we can prove that the soul has no materiality because the materiality of the body consists in a force which violently changes what is felt. This change alone is known to us. But the force which changes and violently alters what is felt has an entirely different concept from what is felt, and one even more different from that which feels; it is brute force opposed to feeling. The soul, therefore, which is the sentient principle has nothing whatsoever to do with materiality; it is immaterial.

434. The same conclusion is reached it we take other properties such as principle. The nature of principle excludes multiplicity, extension and extended matter. The same result is obtained if we begin from the identity of the soul (cf. 140-180). There are, in fact, as many proofs of the simplicity of the soul as there are properties.

Notes

(186) Christian Wolff defends the thesis: 'The attributes of one ens cannot be communicated to any other.' He proves it by having recourse to the principle of sufficient reason as follows. 'Imagine that an attribute, which ens A does not possess, is communicated to it. This attribute has no sufficient reason in the essential constitutives of the ens. Consequently, something is admitted without a sufficient reason. But this is repugnant. The attributes of one ens cannot, therefore, be attributed to another' (Physiologia rationalis, §45). The demonstration is irrefutable.