LS vs IS

After reading those papers, I think I become more confused with the difference between IS and LS.

I don't have much trouble in catching that they ground from seperated communities, have different scope and goals, use different methods and epistemology and history contexts prevent them from being aware of each other. But I kind of find it unclear about their future.

As Duffy described in the paper: "IT tend to focus on the design of the instruction", LS tends to "focus on the learning process and the social context."
LS is "highly interdisciplinary, collaborative approach, derive design principles from a cohesive theory" while IT "spends much time in “defining” principles."
His sense is that "learning sciences field does not give sufficient attention to identifying and testing the role of particular cognitive variables in learning environment."

Duffy also stated in his article, “Should we be reading each other’s literature? I am not sure. To the extent we have different goals, the literature for one group may remain largely irrelevant to the other.”

Then I asked: Is it really necessary to merge these two and is it really possible to merge them in future? It is highly likely that merging them does provide benefits to designers from both parts, but the efforts that spent on merging or acquiring the essense of both may greatly overweight the efforts that designers or technologists can afford to really work out something with expertise in only one field. What is worse, if as duffy mention that they don't go into each other's literature, if a designer or scientist in each field just grap a very small piece from the other that meets their specific needs when they encounter a particular problem, I think it is not a systematic approach to learn and not a good way for the two to merge or benefit from each other.

My another confusion is that: is the difference between LS and IS just the difference between Science and Technology applied to learning? Every science endeavors to generalize theories or principles from cohesive facts and every technology tries to define principles for riching specifi contexts. The distinctions between LS and IS stated in the paper do not seem to give much information or hints to identify their speciality in learning or teaching. (I hope my opinion doesn't go to the extremes) When we studied IS last month, we mentioned that IS focuses on "how to teach", which centers on "instruction"; on the contrary, LS should be concerned more with "learning". It seems to me IS and LS demonstrate the same process but from different perspectives. The former is from the instructor's perspective while the latter from the learners'.
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David Merrill in his paper mentioned that "Theoretical gournding is not a distinction between two disciplines." ("The Science of Instruction andn the Technology of Instructional Design") and he doesn't think these two disciplines share the same but with different philosophies, theories, and methods. Haha, this is a good news to me. Is there significant distinction between these two? :-) Furthermore, he said "Design is not just application of science but is in fact a means to creating its own knowledge base." Is this claim against his previous statement? If design has and is trying to build its own knowledge base, we should say that the design and LS are from different goal and theories. Then why David Merrill still said "There are some issues that have been suggested that I don't believe distinguish these two fields"? Maybe I can ask him tomorrow.