technology INCREASES jobs, never decreases it - over the long term
Counter-points:
If it took several workers to install a door - because it had to be lifted, moved, and held in place while someone put in the bolts to hold it on - or an engine - to lift, move into place, secure, etc - or glass - to move safely into place and secure it - and technology comes along that makes it possible for one worker to do those positions, then the number of jobs has decreased by a significant factor. Might other jobs in other areas be created (e.g to make the technology)? Yes; is the factor of jobs created sufficient to employ those that were displaced? No. For instance, if it took 3 people to install the car door before, but now it takes 1, that's a 3x factor in job loss; if the technology only required a 1 person to build it, then that's only a 2x factor in job creation - not sufficient for job replacement, at least 1 person is still unemployed. In this case it is plausible that both people that lost their job could potentially find an equivalent employment opportunity; but that's not always the case, especially for people that have been on the job for years and are within 10 years of retirement (they'll find it a lot harder to find a new position).
Or take the super markets - it use to be that each checkout lane required at least 1 person to operate (1 for the register, and possibly 1 to bag). However, now with self-checkouts 1 person can now operate 4-6 checkout lanes (as is the case at most grocery stores) or more (as is the case at Walmart) making at least a 4x factor in job loss, in some cases as much as an 8x factor. Does the technology for self-checkouts employ at the same factor? No. The scales simply don't work - there are hundreds of grocery stores, but only a few self-checkout lane manufacturers; so unless that self-checkout lane manufacturer employed at a rate of nearly 10x compared to a 4x job loss, the overall impact is a net job loss. Further, can those employed to run the checkouts (or bag) find equivalent employment? Not necessarily; even having 3 people compete for another job (let alone 3x# of grocery stores) will reduce the wages but also fill up other equivalent positions (at any kind of merchant) very quickly. Further, additional training may be necessary, and not everyone employed in these positions can necessarily receive the additional training to be able to "move up" to more advanced positions. For instance, high school students won't qualify for more advanced positions since they are still in school; many disabled fill bagger-type positions because those fit their skill sets and abilities well.
Or, as others have pointed out, look at the farming sector which use to employ hundreds to harvest a crop at any given farm. Technology has now enabled a handful of people to do the same work in most cases, especially soy, corn, and wheat. (Fruits crops - e.g apples, oranges, etc - still generally require humans due to delicacy of the crop.)
So, like it or not technology does create overall job loss, and economists, who play only in economic theory for the most part, don't take into account the varied types of people in the positions; they always assume that everyone can be trained for a more advanced position, which is not true. It's no different than a computer scientists creating an algorithm based on a Turing Machine with Infinite Memory and Infinite CPU capacity and expecting it to work on equally well on an i386 with 4MB as it does a i7 with 16GB of RAM.