[wolfgke]

> On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" In one case a member of the Upper, and in the other a member of the Lower, House put this question. I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question.

Luckily math has developed methods such as error-detecting/error-correcting codes (to insure against small typos/transmission errors), constructive results on continuity and robustness of functions (i.e. we can prove that if the error in the input data is less than some concretely computable delta, the solution will have an error less than epsilon; or we can ensure that the error in the solution is less than some computable epsilon if we can ensure that the error in the input data "is not too large" (i.e. bounded by some computable epsilon) etc.

In this sense I don't consider the question as that absurd.

[fellellor]

From what I know, error correcting codes wrap around information (in a manner of speaking) so as to provide a measure of consistency, which then enables error correction properties. If the information itself is riddled with errors then the error correcting code can't do anything here.

People using Babbage's machine would have entered raw information into that thing. No error correcting code would correct the human induced flaws in that. So the question was absurd at the time.

[lou1306]

And yet the Schiaparelli lander crashed because the machine couldn't give the right answer to a question that was wrong.

All these solutions are good for a noisy input, but have no use when the input is incorrect (ie. doesn't match reality).