But how are the causal principles different?
As has been explained many times, the actions of inanimate matter are simply reactions to imposed forces, whereas the actions of living organisms are primarily governed by a complexity of self-regulatory systems exhibiting goal-directed action in furtherance of its life.
If you look at a bacterium at a biochemical level, it is essentially a very complex biological machine. All of its functions are deterministic mechanical and biochemical processes directed by code in the form of DNA.
Your choice of words belies your intent. It is the integration of an entire complex of self-regulatory systems which gives rise to life, which is what we mean when we say that life is reducible to a set of biochemical processess. The self-regulatory systems, even in as simple a life-form as bacteria, are not to be likened to programming computers with your “directed by code in the form of DNA.” There exist regulatory systems for repair to DNA damage, such as, for instance, signals that induce an increase in the transcription of genes. These actions exhibit the goal-directedness of the bacterium in increasing cell survival. Likewise, there is bacterial chemotaxis where motile bacteria can direct swimming towards that which furthers its life, and away from that which harms it. This is an adaptive regulatory system which, in effect, detects spatial gradients of amino acids, small peptides, and other nutrients, and which permits a velocity-dependent progress in a valued direction, over time. The self-regulatory systems that are essential to life do not exist in inanimate matter.
I fail to see why a very complex robot would be considered to be philosophically any different.
If you mean what you said literally – philosophically, not scientifically – then indeed it might be rather difficult to discern any one particular instance of actions by a complex electro-mechanical robot from the actions of a living organism. Of course, philosophically, in principle, this is easily taken care of by understanding the differing nature of the two, and, scientifically, by dissecting and determining the causal principles by which the two act.
I have to note that this whole discussion, primarily between yourself, me, and Bowzer, does not seem headed towards resolution. There are only so many ways we can say the same thing, and, for some reason I cannot discern, you just do not seem to “get” what we are saying. Perhaps it is time for a break. Maybe looking at these posts sometime later, something might “click.”