Ontology and Universal Nature
Different assumptions are made by scientists and others who study the human society and world in general. Some scientists assume that there are objective rules governing the world and universe, while some assume that phenomena occuring are dependent on the contexts. Formation of assumptions or perspectives (or views) could be seen clearly in the religious arena as well. Religions also make various assumptions about the world and human beings. Based on the belief that there is no life after death (or no rebirth) some relegions assume that human actions are not followed by their results. On the other hand, religions that hold the belief of a creator God assumes that the world exists according to the laws made by the creator. Hence, some declare that there exists an objective world.
On the contrary, Buddha did not declare that everything in the world is either objective or subjective. Having realized the role of perceptions, views (see the footnote) and grasping he declared that the whole world can be found in the fathom long body. When asked whether he was a man, the Buddha answered no. Similarly, when asked if he was a god, brahma, or yakka etc. the Buddha's answer was negative. He knew the subjective nature of the worldly knowledge. All the beings - humans, gods, brahmas - are with minds that could get defiled by ignorance, anger and greed. On the other hand, the Buddha eliminated such defilements from his mind. Therefore, in order to show the difference between the beings who have defiled mnds and the Buddha without the defilements, he did not affirm that he was a man, god or a brahma. The Buddha realized the necessity to transced this subjective knowledge or to use the subjective knowledge for further development of wisdom.
Moreover, with the realization of the role of the positive mental faculties such as mindfulness, effort, concentration, confidence (sraddha), and wisdom he decalred the non-deterministic nature of the universal laws. He states that if the universal laws are deterministic then Nirvana is not possible. Hence, due to non-deterministic nature of these laws it is possible to change the course of samsaric existence and attain Nirvana. As a Bodhisatva, he discovered behaviors needed for gaining the understanding necessary for showing the others the path to Nirvana. He practiced the 'perfections' or paramitha relentlessly showing the non-deterministic nature of some of the universal laws. He realized the changing nature of things and phenomena and that existence is subject to suffering . Hence, he did not declare that everything is subjective.
Irrespective of the contextual factors, everyone undergoes suffering and and is subject to change. Whether a person is rich or poor, black or white, thin or fat, wise or foolish etc. she/he is overcome by this unsatisfactoriness and change at some point in life. Hence, the Buddha declared that ultimate truth is the four Noble Truths. These Truths are neither created by the Buddha, nor a verbalization of his imaginations. Instead, he realized the existence of these Truths in the universe.
Old age, disease, and death come to everyone without even wishing for them. Moreover, these are common to everyone. Even the strong 'body builders' are overpowered by sicknesses. Similarly, things around us change whether we wish for the changes or not. Buddhists perform a simple experiment everyday when offering flowers to the Buddha. When we observe the flowers that are offered to the Buddha, we can realize that they are beautiful (with niec coloers, pleasant smells and softness). As the time passes by, the colors fade or discolorations occur, the softness is replaced with roughness and dryness, and intensity of the scent decreases. Changes occur in the flowers. Ultimately we throw away the flowers offered to the Buddha because they have become very unpleasant. The Buddha stated, "all conditions things are subject to change. When the conditions that cause them change, the result changes too. Therefore, be dilligent and follow the path." Only through following this path dilligently that a person can transcend the subjectivity and overpower the objective impermanence to realize the absolute happiness of Nirvana.