Antonyms of adj illogical

2 senses of illogical

Sense 1
illogical (vs. logical), unlogical -- (lacking in correct logical relation)

logical (vs. illogical) -- (capable of or reflecting the capability for correct and valid reasoning; "a logical mind")
        => dianoetic, discursive -- (proceeding to a conclusion by reason or argument rather than intuition)
        => formal -- (logically deductive; "formal proof")
        => ratiocinative -- (based on exact thinking; "one's ratiocinative powers")

Sense 2
confused, disconnected, disjointed, disordered, garbled, illogical, scattered, unconnected -- (lacking orderly continuity; "a confused set of instructions"; "a confused dream about the end of the world"; "disconnected fragments of a story"; "scattered thoughts")

INDIRECT (VIA incoherent) -> coherent, consistent, logical, ordered -- (marked by an orderly, logical, and aesthetically consistent relation of parts; "a coherent argument")

Similarity of adj illogical

2 senses of illogical

Sense 1
illogical (vs. logical), unlogical -- (lacking in correct logical relation)
       => absurd -- (inconsistent with reason or logic or common sense; "the absurd predicament of seeming to argue that virtue is highly desirable but intensely unpleasant"- Walter Lippman)
       => inconsequential -- (not following logically as a consequence)
       => intuitive, nonrational, visceral -- (obtained through intuition rather than from reasoning or observation)
          Also See-> incoherent#1; irrational#1; unreasonable#1

Sense 2
confused, disconnected, disjointed, disordered, garbled, illogical, scattered, unconnected -- (lacking orderly continuity; "a confused set of instructions"; "a confused dream about the end of the world"; "disconnected fragments of a story"; "scattered thoughts")
       => incoherent (vs. coherent) -- (without logical or meaningful connection; "a turgid incoherent presentation")