Relationship of cigarette smoking and snuff dipping to plasma fibrinogen, fibrinolytic variables and serum-insulin: The northern Sweden MONICA study
That is, when you are reasoning by sign, you are not saying that smoke causes fire but that from our observation of smoke, we can assume the presence of fire. If we were to use reasoning by cause, we might state that: because fire causes smoke, if I start a fire, there will also be smoke. In the example of reasoning by cause, we infer that something will happen based on the occurrence of something else
You should always check the policy of the mode of transportation before you board
The issue grows more complicated when dealing with large animals or those that require specialist handlers to free safely, but in the case of one cigarette butt, it seems reasonable to assist the fish in making better decisions (a bit like this octopus who switched their plastic home for something fancier)
Some causes can be minor and others that can be life-threatening