For what it's worth, I think I might agree with you (at least in some respect).
Looking at life to detect if it is intellgently designed can be a perfectly scientific endevour. It was basically this that lead us to the conclusion that life was designed, but there is no need to interject an intelligence behind the design given the evidence we have so far compiled.
Hypothesizing that there might be evidence yet that would be indicative of some kind of intervention in the development of life, is also scientific. However, where ID gets into difficulty is in the details of the intervention. In order for it to succesfully create an explanatory framework (and find itself with a theory) it will need to explain how this entity interacts with life, and then seek evidence of that form of interaction.
Without this kind of investigation, ID can continue hypothesizing about things for eternity, but saying 'The intelligent designer did it in some undetectable manner' is using the old theological wording of 'I don't know' and replacing God with intelligent designer. So here's the rub - the concept of seeking intelligent design can be a scientific endevour, but as it stands ID is a political movement, with a lot of 'God did its' (but without trying to use the word God). What science they have produced has been shown to be good looking but basically falsified.
SETI is scientific because we know it is possible to employ the EM spectrum in a manner conducive to communication. Such communication might be undetectable to us, but it probably has significantly different characteristics from the rest of the noise out there, so we are more than likely going to be able to detect it if we receive it. Life poses an inherent difficulty to us. Since we don't have a massive sea of known undesigned life (noise) there is no way for us to compare it to life on earth to see if it has characteristics of known designed life (Which we unfortunately lack too). This is the big gap between SETI and ID, and ID suffers for it.
Hearkening back to the topic for a moment (and I don't know if that has been included in the context of the SETI/ID discussion) but I think Macneil has an interesting point to make about the Cornell seminars:
Allen MacNeill writes:
...by studying what I believe to be a flawed attempt at identifying and quantifying design or purpose in nature, we may be able to do a better job of it. Clearly, there are purposeful entities capable of “intelligent design” in the universe: I am one and I infer that you are another. There are also objects and processes that clearly are not: the air we are both currently breathing clearly fall into this class. As a scientist committed to naturalistic explanations for natural phenomena, it is clear to me that there must be some way of discerning between these two classes of objects and processes, as both of them are clearly “natural.” Therefore, we will use several approaches to the identification and explanation of design and purpose to do so.
™ Version 4.2
