The role of sculpture for Tucker is fundamentally a passive one: other things act upon the sculpture, actions of giving light or moving belong to the world or to the viewer. As Tucker says in the introduction to The Condition of Sculpture:

‘When we speak of sculpture as ‘active’ we do so metaphorically:
at most it resists our gaze, receives light, withstands gravity.’

It is important to point out that when Tucker speaks of an intellectual appreciation of sculpture this has nothing to do with ‘meaning’, or at least any sense of meaning outside of an essentialist meaning of sculpture as sculpture. It is also worth pointing out that such a narrowly prescriptive and passive view of sculpture already had its critics and dissenters in the 1960s. During that decade a range of activities began to interrogate the parameters of sculpture practice, perceiving it as an expanded idea rather than the strictly formal concept adhered to in Tucker’s writings. Many of these activities simply lie outside of Tucker’s definition of ‘sculpture’ since they offend against its basic conditions, for example the walks of Richard Long. Other works of sculpture would be difficult to discuss in Tucker’s terms since they have concerns outside of those he is prepared to acknowledge as pertinent to sculpture, for example works by Carl Andre. If Tucker’s views were being critiqued and questioned in the 1960s, by 1975 they were considered by some to be strictly partisan. The motivation of Tucker’s writing had seemed, in the 1960s, to be an open-ended enquiry into the nature and possibilities of sculpture. By the mid-1970s, and particularly in the introduction to The Condition of Sculpture, Tucker’s prose had hardened into an unshakeable dogma and a carping criticism of avant-garde theory, the tone of which did little to enhance the serious thought and valuable insights of Tucker’s writing.

One of the areas in which Tucker’s writings show particular insight concerns the relations of sculpture and space: the space of the world, the space of the viewer and ‘public space’. As well as being a free-standing object, there is another sense in which sculpture is in the world and relates to the world, and this concerns its immediate surroundings: its location and environment. A clue to Tucker’s views on this lies in the quotation by Rainer Maria Rilke with which Tucker begins his introduction to The Language of Sculpture:

‘It [sculpture] had to be fitted into the space that surrounded it,
as into a niche; its certainty, steadiness and loftiness did not spring
from its significance but from its harmonious adjustment to the
environment.’

This ‘harmonious adjustment’ bears some similarities to notions of ‘site specificity’; a term current in relation to sculpture since the mid-1960s. However a ‘harmonious adjustment to [its] environment’ is still quite a way from the strictest sense of site-specificity where the sculpture is made exclusively for that place (a good example would be Richard Serra’s Tilted Arc) or is actually made of the materials of that site (for example Robert Smithson’s Spiral jetty). However, it is important to note this concern with sculpture’s relationship to its environment for it serves to problematise any simplistic understanding of Tucker’s other notions about sculpture being ‘homeless’ or ‘free-standing’. These concepts must be understood in the context of an idea of sculpture already in the world and in relation to that world. Sculpture, for Tucker, unlike the arts of poetry, painting or music, cannot be an ‘occasional’ art, enjoyed and then stored away. Sculpture is in the world in a much more physical, inconvenient and obtrusive way, more like architecture.

For Tucker, the relation of sculpture to the viewer or spectator is one of private contemplation via the viewer’s mental faculties. However, for Tucker, the relation of sculpture to a more abstract notion of ‘the public’ is much more problematic. Sculpture can become ‘public’ in different ways. It can become public having been made privately and then being placed in a public space or it can be ‘public sculpture’, designed and made for a particular place, often as the result of a commission or competition. It is this second sense of ‘public sculpture’ that Tucker finds most objectionable. In addition to his view that competitions place detrimental and limiting strictures on the sculptor, the real problem seems to lie with the expectations of sculpture’s supposed public function. Tucker wrote in 1969:

‘For there is no public realm in our time to which a public
sculpture might give visual purpose.’