 Three sorts of evidence relevant to the existence of an apple are mentioned: perceptions of its several sensible qualities, perceptions of its effects in conjunction with objects of various sorts, and indications of the manner in which it was formed. The evidence we have that, say, a seeming particular thing is an apple might include perceptions of its round figure and pleasing taste, observations of its turning brown after exposure to air, and report of its having been picked from a tree. Let’s call this group of traits “T”. To evaluate this evidence, Shepherd invokes the notion of the “apparent cause”. The apparent cause in the case in question is an object of the kind apple. There is a certain regularity with which active causes that belong to the kind apple exhibit traits T. There may be one or more other kinds of objects that are found to have traits T with greater or less regularity. Although things in these other kinds satisfy part of the definition of the apparent cause, they do not satisfy the remainder.