Image: The statue of Descartes on the yard of the Ecole Normale Superieure in Paris. Kind of demonstrating the problems of dualism.

With “dualism” I mean substance dualism, which is the opposite of monism, the view that our world is consisting of one substance. Substance dualism claims that the world is divided to two parts: one material part and one spiritual. Monism usually means materialism, but the subjective idealism of Berkeley is also a kind of monism. I will not deal with this one now, because it has very few followers, while substance dualism is the accepted view of most monotheistic religion. I will speak about this substance dualism from the viewpoint of the philosophy of mind and from the perspective of life after death. Substance dualism can be criticised in this two aspects similarly, because of unresolvable problems. One problem would be of epistemic kind the other the well known problem of mental causation.

Both idea are connected to religion as well. The mind-body dualism, because the three monotheistic religion believes, god created humans, and their transcendent soul is made by god. And vice-versa, the phenomena that point according to their view to a transcendent soul, they regard as a proof of god. The dualistic worldview with the belief in an after-life is obviously connected to the religious faith. The transcendent world is not only the home of death people, but also of god. Here, they regard the phenomena hinting to a life after death as a proof of after-life.

Let us start with the body-mind dualism. It is well known that already Descartes realized that the substance-dualism is connected to an immense problem, namely, if the soul is not material, then how can it cause phenomena in our body, and through our acts in the world, that are obviously of a material kind?! One untenable “solution” is that the seeming correlations of our thoughts and the happenings in the material world are not of causational art, they are either mere coincidences, or caused by god. In the first case the transcendental phenomena of the soul were unnecessary, so called epiphenomenal hypotheses. And according of the principle of Occam’s razor, we shall discard such hypotheses. In the second case the hypothesis of the substance-dualism was resulting in a problem, for which the alleged solution is god, but this is also an unnecessary complication and the razor of Occam shall cut off god. In this case we have not only that god is an unnecessary complication, but this god also has to create the harmony at each of the phenomena of the soul. Since this is not done by causation.

There is a fundamental problem here in dualism: if there are two kinds of substances, then how is the world unified? And if the world is a single one, then how can it consist of two substances? If the non-materialistic substance can cause a material phenomena, why do they call it non-matierial substance?

Now, Descartes thought to resolve the problem by assuming, there is an interaction happening between the material and the non-material in the pineal gland, the pineal gland being the principle seat of soul. Like if the specification of an exact location would resolve the how could such a conceptual absurdity happen. With specifying the exact location as the pineal gland, this hypothesis was even more clearly refuted, as we know, what the pineal gland is, and what it serves for, and that its role is important to regulate sleep, but not very crucial for consciousness.

Now the situation with the after world or with the god in this after world is similar, with an important difference that most of the believers think it as being in another “dimension”, or space-time. But still, the problem is similar. Independently of this other space-time, if it is another substance, how can god, or, how can spirits or ghosts interact with the material substance?! And vice versa, if it has an effect on the material, how is it another substance?

A frequent “argument” of the believers is that science is not capable to know the transcendent world. But in the method of science there are no restrictions about substances, nor about “dimensions”. For the scientific method, space-time can have as many dimensions it will, and there could exist as many “substances”, that could not consist of an obstacle for science. The only thing important for the scientific method is: statements shall be confirmed. For the sciences about reality, confirmation means empirical confirmation. And that only needs one thing, namely the claimed interaction with material.

The famous principle of Berkeley: “Esse est percipi” (“to exist is to be perceived”) 1 lead him to subjective idealism, but their is some truth in it. Another, similar principle could be that “to exist means to have effects”. This is similar, because things are perceived trough their effect. And a third definition of existence could be that to exist means to be confirmed, or as Carnap put it: „To be real in the scientific sense means to be an element of the system”2 ,where “system” means the accepted scientific theory. Now, let us examine these three principles!

  1. Let as call the entities that can be perceived directly, or accessible indirectly empirically as the empirical Universe.
  2.  The impact Universe: those entities that can have a direct or indirect effect on us.
  3.  The confirmation Universe: the set of those entities that can be confirmed to exist by the scientific method.

From a practical point of view it seems that 2. the impact Universe is the most important. The most important thing about the existing entities is that their have an effect on our life. If something is effecting us, it is important to know about it. If something has not even an indirect effect on us, it is all the same if we know about it, or not. For example if the believers claim there exists a god, but it has no effect on our life whatsoever, then why would we care?

Definition 3. is formulated from the aspect of scientific method and its reach. Here we define what science may know.

Now, let us note  all three definitions are to be understood in a potential manner. I say something to exist in an empirical way that can be perceived, but also those entities that could be perceived indirectly. Anything belongs here that can be measured or detected by any means. Even those things for which we do not have currently a device, but such a device could be principally constructed.

Similarly, the effect Universe does not only consist of the entities that have currently a direct effect on us, but everything, that could have an effect on us in any indirect way, if we were in the right place at the right time.

The confirmation Universe does not only contain the entities that are confirmed according to our current knowledge, but everything, science could by principle confirm.

Now, my statement is that the three universes, the empirical, the effect and the confirmation Universe are the same set. It is trivial that if the empirical science does confirm something, it does it so that we have to perceive something,  at least a measuring device. Also the other direction is obvious: if something is empirically accessible, it can be confirmed.

It is only a little bit more complicated to admit that everything that is empirically accessible, has an impact on us. For this we have to get rid of the naive belief that perception is not a physical process. Because certainly all perception is based on physical processes, and on effects. If we see something, it is, because some photons have an effect on our retina. If we hear something, it is, because something has an effect on our tynpanum through the waves that are spreading in the air. And so on. There is no perception without an effect on some of our sensing organs.

The reverse order is a little bit more complicated. Her we have to get rid of the belief that empirical perception is only our own, direct perception. We have to assume that we have a lot of intelligence to visualize a lot of things. Now, let us assume that an object T has an effect on us, at least an indirect effect! This effect has to change something in us. Some position,ingredients, mass, velocity, or whatever. All these changes are measurable in some way. If T has an effect on C and C has an effect on us, then the change is measurable in us, but also another change is measurable in C, since C had a direct effect on us, so we have to access C. If something is indirect, we have to remind ourself that the principle is more complex, but it remains valid.

And now, let us ask ourself, is it possible that something cannot be confirmed empirically, and has no effect on us nor to the material world? Such a thing will not exist for us at least. Moreover, for us, it is totally irrelevant if it exists, because it has no effect whatsoever, so it does not change anything in our life. Such an entity cannot be confirmed by science. But such an entity is purely metaphysical. It does not make sense to speak about such entity. According to the view of the logical positivists, to speak about such entities is actually insensible.

Of course, a lot of religions may speak blah-blah about such thing, but we cannot consider this from any rational point of view. Such a blah-blah is only good for one thing: it may result in the horrors of religions that we know so well.

1 George Berkeley: „A Treatise Concerning the Principles of Human Knowledge”, first chapter.

2Rudolf Carnap: „Empiricism, semantics, and ontology” in „The philosophy of science”, MIT, 1991, p. 86.