A priori and a posteriori in the context of "Branches of science"

Immanuel Kant (born Emanuel Kant; 22 April 1724 – 12 February 1804) was a German philosopher. Born in Königsberg, he is considered one of the central thinkers of the Enlightenment. His comprehensive and systematic works in epistemology, metaphysics, ethics, and aesthetics have made him one of the most influential and highly discussed figures in modern Western philosophy.

In his doctrine of transcendental idealism, Kant argued that space and time are mere "forms of intuition [German: Anschauung]" that structure all experience and that the objects of experience are mere "appearances". The nature of things as they are in themselves is unknowable to us. Nonetheless, in an attempt to counter the philosophical doctrine of skepticism, he wrote the Critique of Pure Reason (1781/1787), his best-known work. Kant drew a parallel to the Copernican Revolution in his proposal to think of the objects of experience as conforming to people's spatial and temporal forms of intuition and the categories of their understanding so that they have a priori cognition of those objects.

Ad hoc is a Latin phrase meaning literally 'for this'. In English, it typically signifies a solution designed for a specific purpose, problem, or task rather than a generalized solution adaptable to collateral instances (compare with a priori).

Common examples include ad hoc committees and commissions created at the national or international level for a specific task, and the term is often used to describe arbitration (ad hoc arbitration). In other fields, the term could refer to a military unit created under special circumstances (see task force), a handcrafted network protocol (e.g., ad hoc network), a temporary collaboration among geographically-linked franchise locations (of a given national brand) to issue advertising coupons, or a purpose-specific equation in mathematics or science.

In the philosophy of religion, an ontological argument is a deductive philosophical argument, made from an ontological basis, that is advanced in support of the existence of God. Such arguments tend to refer to the state of being or existing. More specifically, ontological arguments are commonly conceived a priori in regard to the organization of the universe, whereby, if such organizational structure is true, God must exist.

The first ontological argument in Western Christian tradition was proposed by Saint Anselm of Canterbury in his 1078 work, Proslogion (Latin: Proslogium, lit. 'Discourse [on the Existence of God]'), in which he defines God as "a being than which no greater can be conceived," and argues that such a being must exist in the mind, even in that of the person who denies the existence of God. From this, he suggests that if the greatest possible being exists in the mind, it must also exist in reality, because if it existed only in the mind, then an even greater being must be possible – one who exists both in mind and in reality. Therefore, this greatest possible being must exist in reality. Similarly, in the East, Avicenna's Proof of the Truthful argued, albeit for very different reasons, that there must be a "necessary existent".

Sensor fusion is a process of combining sensor data or data derived from disparate sources so that the resulting information has less uncertainty than would be possible if these sources were used individually. For instance, one could potentially obtain a more accurate location estimate of an indoor object by combining multiple data sources such as video cameras and WiFi localization signals. The term uncertainty reduction in this case can mean more accurate, more complete, or more dependable, or refer to the result of an emerging view, such as stereoscopic vision (calculation of depth information by combining two-dimensional images from two cameras at slightly different viewpoints).

The data sources for a fusion process are not specified to originate from identical sensors. One can distinguish direct fusion, indirect fusion and fusion of the outputs of the former two. Direct fusion is the fusion of sensor data from a set of heterogeneous or homogeneous sensors, soft sensors, and history values of sensor data, while indirect fusion uses information sources like a priori knowledge about the environment and human input.