Is this an ashtray? A round glass container of which the rim has three indents? 

How do I know for certain that this is an ashtray? How can I state for certain that the function of this object could be: a) to hold a burning cigarette in one of the three indents in the rim of the glass container while the smoker is occupied with other matters. b) to collect the ash tapped off a cigarette within the glass bowl. c) to accept the extinguished cigarette in the glass bowl after it has been partially or completely consumed according to the inclination of the smoker.

Can this round glass container of which the rim has three indents also be an ornament that people place in their homes to: a) enjoy the play of light that occurs within the wondrous world of this glass object. b) fill out a bare or empty place in the home that without the glass object would seem bare or empty. c) see the colours of their interior reflected in its surface that due to its transparency always blends in with its surroundings.

Can this round glass container of which the rim has three indents also be a wine glass because: a) they are both made of glass. b) they are both round. c) they both serve as a container.

Can this round glass container of which the rim has three indents also be a telephone because: a) both have a function. b) both are handy. c) both can be of service in both professional and domestic situations.

Can an ashtray, just like any decorative object serve to make an empty space look less bare? Can you serve wine in an ashtray and tap off your ash in a wine glass? Can an ashtray, because of its industrially manufactured character represent modernism? Can you phone your nephew in Canada with an ashtray? How do I know for certain that this is an ashtray?

Can this round glass container of which the rim has three indents also be an objet d’art that: a) due to its industrially manufactured character represents modernism. b) denies its own existence and represents immateriality because of its transparent and reflective character. c) because of its modest size and appearance becomes part of daily life, thereby offering new perspectives on the relation between daily life and art.