【Indicate】 , 【betoken】 ,  【attest】 , 【bespeak】 ,  【argue】 ,  【prove】  can all mean to give evidence of or to serve as ground for a valid or reasonable inference.

One thing indicates another when the former serves as a symptom or a sign pointing to the latter as a justifiable or necessary conclusion, treatment, or remedy.

One thing betokens another when the former serves as visible or sensible evidence or, more narrowly, as a presage or portent of the latter.

One thing attests another when the former serves as indisputable evidence of the latter and has the force though not necessarily the character of legal testimony or documentary proof.

One thing bespeaks another when the former leads to the inference that it is the outward manifestation of the latter.

One thing argues another when the former gives good reason for belief in the existence, the reality, or the presence of the latter.

One thing proves another when the former serves to demonstrate or manifest the truth of the latter.