Magritte would probably say that this (Figure 1) is not a bike.
And he would be correct – but only thanks to technicalities. This (i.e. Figure 1) is indeed not a bike: it is a set of pixels on a screen that evokes bicycleness. And ‘This’ is not a bike either: it is the word ‘This’.
I am less literal than Magritte: for me, Figure 1 depicts a bike. This, however, is definitely not a bike (Figure 2), and does not depict one.
It is a unicycle – or a pixelated evocation of a unicyle for the purists out there. Why is it not a bike? Because a BI-cycle has TWO-wheels, whereas a UNI-cycle has ONE-wheel. Logical.
A bike is not necessarily a bike
BUT – there are two theory-of-bike ( i.e. philokuklical ) issues with the idea that a bike is a bike.
The first issue is logical, and can best be understood by thinking through the following syllogism.
1- Someone who rides a bicycle is a cyclist because they ride a bicycle.
2- Someone who rides a unicycle is a cyclist because they ride a unicycle.
3- Someone riding a unicycle must therefore be riding a bicycle (and vice-versa).
The second issue is legal, but can also be expressed as a syllogism:
1- There are byelaws in most cities stipulating that bicycles should not be ridden on sidewalks.
2- Under these bylaws, people riding a unicycle are ticketed for riding on sidewalks (see here and here)
3- Therefore a person riding a unicycle on a sidewalk is riding a bicycle.
Ontario Ministry of Transport: a unicycle is a bicycle
The Ontario Ministry of Transport has clearly specified that a unicycle is a bicycle (Figure 3), though only unicycles with handlebars (!) are bicycles.
Despite syllogisms and surreal ministerial diktats, New York judges suggest that bicycles are bicycles and that unicycles are not.
Indeed, the fine levied by New York City on one sidewalk-riding unicyclist was thrown out, as was another a few years earlier. So, in New York at least, judges accept that bikes are essentially (i.e. it is their essence to be) two-wheeled.
Is a bike a bike? Maybe.