Relations, Dimensions, Time, and Space

Is time really a 4th dimension? I think it depends on how you look at it. But the number 4 is definitely arbitrary.

Any attribute of an existent may be thought of as a dimension of a relation over existents on the continuum or field of that attribute. The three spatial dimensions do not exist as such, but are attributes of existents measuring their particular boundaries or orientation relative to each other.

Time, on the other hand, does not measure any particular attribute of an existent. It measures all of its attributes in unison. Time is a measure of existence itself. It provides the sequential attribute of causality as we track which existents are concurrent and which occur separately.

Time, therefore, is a kind of dimension. A continuum on which things come into existence and then cease to exist. That doesn't make time special in that it's somehow grouped with the spatial dimensions, and doesn't validate the concept of "spacetime".

An object's color can be thought of as a dimension. As can its number of vertices, its intelligence, its similarity to a carrot, or any other conceivable attribute.

It's hard for us to conceive of the fact that time and space do not exist except in the mind. They are concepts. They're data. They are relations over attributes of things that do exist.