Why were all NS-2 manufactured without the serial numbers?

Question

In the story "Little Lost Robot" from I, Robot, a modified Nestor (NS-2) hides himself in a cargo with 62 other physically identical robots.

I think one of the main reasons why the hiding robot was not easily identifiable was NS-2s did not have any serial numbers.

In the story general mentions:

‘But we had to have robots of a different nature. So just a few of the NS-2 model, the Nestors, that is, were prepared with a modified First Law. To keep it quiet, all NS-2s are manufactured without serial numbers; modified members are delivered here along with a group of normal robots; and, of course, all our kind are under the strictest impressionment never to tell of their modification to unauthorized personnel.’ He wore an embarrassed smile, ‘This has all worked out against us now.

It seems only a few NS-2 had modified first law but all of them were missing the serial number. I am not clear on how not having serial number was helpful to keep the operation quiet.

Answer 1

Not having serial numbers means there is no physical way to tell the modified ones from the non modified ones. ALL are free of serial numbers, but only a few are modified.

Answer 2

It has been a long time since I last read "Little Lost Robot," but I seem to remember there having been a sort of trope about inefficient, bumbling, and stupid government agencies (and bumbling commercial entities) in the robot stories.

The government insisted on the modified NS2 robots to work in the hyperspace research project. It also insisted on the lack of serial numbers.

So you've got a government agency that has insisted on having something stupid done, and now has to be rescued by the overworked, underpaid, very clever underdog heroes.

The "stupid government agency" provides the cover for what is essentially a plot device - if they had serial numbers there'd be no mystery to solve and no story. "Stupid government agency" insists on not having serial numbers - mystery, let's write a story.

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Not knocking the story, by the way. I really liked the Powell and Donovan stories.

Answer 3

Most of the people working with the Nestors were unaware that there were ones out there with illegal modifications. And they weren't supposed to find out. Hence no paper trail, which serial numbers would implicate inevitably.

Having some with and some without serial numbers would cause instant suspicion that there was something strange about the ones without, can't have that.

Of course it'd have been far easier to issue them all with serial numbers and simply not enter the modifications in the documents released for general consumption, only keep that list in the company HQ computer systems.

But if they'd done that there'd have been no story.

Answer 4

For double blind test, you need test group and placebo group. And the researcher doing the testing must not know which group is which so they won't unconsciously have effect on the results,by treating the two groups differently. If you know that a robot is the one with modified first law, you will act differently towards it than the regular one, even if subconsciously. Robot could detect it and change its own reactions to your treatment.

Thus invalidating the test.

More information here: blinded experiment.

Edit: They (government/military) created modified Nestors for a reason. That reason is to test whether modified first law will function well enough when robots have to work alongside humans in dangerous environment. If you want to properly test THAT, humans mustn't know, less they influence the results of test. My understanding was that if this test was successful, it would have lead to wide adoption of modified Nestors in locations and situations where unmodified models couldn't previously work, due to "strict" implementation of the first law. As in, through inaction part letting humans come to harm. For example: They would prevent a human being from entering radioactive parts of the station to shut down faulty reactor because radiation would harm humans. If it was necessary to contain leak or shutdown a reactor to prevent catastrophe, human would be unable to do the job because of a robot preventing it.