Critical realism is the doctrine accepted by some philosophers sympathetic to the view of R.W. Sellars, as published in Critical Realism (1916).
Critical realism retains the belief of common-sense realism in independant physical things, but admits that these are not directly and homogeneously presented to us in perceptual situations.
These latter are thought to be very various, and out understanding of them must depend in part on the qstate and findings of the natural sciences. Thus the after-image, the foot is felt after the leg has been amputated, and other cases call for different explanatory accounts.
In general, critical realists hold that knowledge of the world can be gained because there is some sort of reliable correspondence between sensa, or some sort of intuitive data, on the one hand, and external objects on the other.
Critical Realism vs Idealism
Critical realism is historically the successor to idealism. It conceded to idealism that whenever something is perceived it is an object for a mind, but insisted that is does not follow from this that something has no existence except in its being perceived.