Did I say it was? I argued for 16 on the basis of this comment thread.
All countries have constraints based on mental competency. The point is that a typical 16 year old (and yes, probably 15 year olds too) are well above the mental capacity where we still allow adults to vote.
The current age limits are not justified with any evidence of that the group is substantially less competent to make the relevant choices than many other subsets of the population that we don't hesitate to allow to vote. If someone for example started arguing for iq tests, or a test on knowledge of current affairs, it would be exceedingly hard to put the barrier low enough to not exclude any enfranchised adults, and you'd almost certainly end up including children well below the age of 16 (e.g. political youth parties in many countries have a lower age of 14, some even lower, and you'll find people in those organisations that are schooled in political science beyond what most adults ever will be).
This would not extend to 1 day old babies because a 1 day old baby lack the ability to make any kind of informed choice. In fact, a 1 day old baby lack the physical ability to observe the alternatives and indicate a choice. They would be excluded by any kind of mental competency standard.
Where exactly to draw the line would be hard, but expect it to drop substantially over time, as it already has.
All countries have constraints based on mental competency. The point is that a typical 16 year old (and yes, probably 15 year olds too) are well above the mental capacity where we still allow adults to vote.
The current age limits are not justified with any evidence of that the group is substantially less competent to make the relevant choices than many other subsets of the population that we don't hesitate to allow to vote. If someone for example started arguing for iq tests, or a test on knowledge of current affairs, it would be exceedingly hard to put the barrier low enough to not exclude any enfranchised adults, and you'd almost certainly end up including children well below the age of 16 (e.g. political youth parties in many countries have a lower age of 14, some even lower, and you'll find people in those organisations that are schooled in political science beyond what most adults ever will be).
This would not extend to 1 day old babies because a 1 day old baby lack the ability to make any kind of informed choice. In fact, a 1 day old baby lack the physical ability to observe the alternatives and indicate a choice. They would be excluded by any kind of mental competency standard.
Where exactly to draw the line would be hard, but expect it to drop substantially over time, as it already has.