I infer that the intellect is immaterial, but my inference from the empirical data and my personal experience is not a theological but a philosophical inference. It belongs to the subject of philosophical psychology, not scientific psychology.
Again, back to forensics. When an accident scene is evaluated, scientists can determine if something happened by chance, by a natural process, or by an intelligent plan.
The scientific, empirical evidence is evaluated through a scientific process. The inference that can be drawn from the analysis is that the crime occured – it was not an accident.
So, by analogy, when one observes indications of the work of intelligence in nature – it’s reasonable to conclude, through scientific means, that the object being observed was formed or developed with the influence of a coordinating intelligence. Why? Because science can observe the products of human intelligence and can recognize patterns that are the hallmarks of purposeful, intelligent design.
You ask why Michael Behe would say that the evidence that ID uncovers could point to alien beings (and not necessarily to God) – and that is because the nature of the designer (the owner of the intelligence at work) is not the subject of ID research.
The only difference in this view as with your conclusion that the mind is immaterial, is that ID proposes a model for “designed things” – some kind of definition that would separate products of intelligence from what is created through random or natural processes.
This is done through probability studies. If known natural laws cannot explain the object, and the object gives evidence that parallels what is only produced by intelligent agents – then a reasonable conclusion is that some intelligence (of some kind, from some source) was involved in the creation of the object.
When you posit that the mind is immaterial, after investigating the empirical evidence, you are proposing something that cannot be modeled in nature (immaterial things). So, yours would be a philosophical inference. The difference with ID is that “intelligently designed things” can be recognized by science – analogously through what human beings produce.
If chance or natural laws do not have the power to produce the object in question – and the object resembles only what we know to be produced by intelligence (for example, software language) – then the inference that this object was produced with the help of some intelligence is a reasonable one.
In the case of the Mind – you can see that chance and natural laws cannot explain the origin or function of human consciousness. Now to draw the inference that the mind is therefore immaterial, however, is a different sort of conclusion. It would be philosophical because science cannot directly study immaterial things.
Whereas, science can study the products of intelligent design.
Researchers, for example, finding some logs piled up in a stream – could recognize a pattern, order and purpose. They conclude that the log pile was intelligently designed. In this case – not by supernatural intelligence, but by animal intelligence (it’s a beaver dam).
Now if they had never heard of beavers, the researchers could still conclude that some intelligence was at work. To conclude that God created the dam would be incorrect. But ID doesn’t seek to identify who the designer is - because that is outside of what science can do.
ID cannot tell us precisely what designer is indicated by the empirical data. Some aspects of the designer can be identified – great intelligence, great power, organizing properties … a few things like that.