The word consequence can mean:

— Effect, referring to a causal, cause / effect relationship S. Causality.
— Consequent, referring to a logical, antecedent / consequent relationship, S. Connectives, §Implication

1. Effect-to-cause argumentation

The effect to cause argument goes back from the consequences to the cause. Given data is considered the effect of a hypothetical cause that can be reconstructed on the basis of this data combined with a known causal relationship between these type of facts and their cause. Other expressions can also be used, such as argument by the effect, or from the effect to the cause.

You have a temperature, so you have an infection

— Argument: A confirmed fact t, the patient’s temperature. This fact t belongs to the category of facts or events T, “having a temperature”, as defined by medicine. This is a categorization process.
— Causal Law: There is a causal law linking I facts “having an infection” to T facts, “having a temperature”
— Conclusion: t has a type T cause, an infection, and the patient should be treated accordingly.

This corresponds to the diagnostic process; one could speak of diagnostic reasoning.

The effect (the temperature) is the natural sign of the cause. Such natural, palpable, effects provide endless basis for argument by natural signs:

See! The cinders are still hot, there was a recent fire (… they cannot be very far)

In the area of ​​socio-political decision, the argument by the consequences corresponds to the pragmatic argument, transferring upon the measure itself the positive or negative evaluation of the effects of a proposed measure.
The pathetic argument scheme is a special kind of pragmatic argument.

The argument from the consequences is sometimes referred to in Latin as argumentation quia “because” in opposition to the arguments by the cause or propter quid “because of which”.
S. A priori, a posteriori.

2. Arguments by the identity of the consequences

The same kind of argumentation applies to deductions made from the implied meaning of words, as an appeal to the sense of semantic coherence or logical consecution:

Scheme: “Another topic consists in concluding the identity of precedents from the identity of results”
Instance: “There is as much impiety in asserting that the gods are born as in saying that they die; for either way the result is that at some time or other they did not exist” (Aristotle, Rhet. II, 23, 1399b5; F. p. 313-315).

If something is condemned because it forcibly involves mechanically something negative, then it automatically creates a category of causes “having that kind of negative consequences”, which must also be condemned. If the reason given for banning the consumption of marijuana is that it causes a loss of control, then all substances that cause a loss of control must also be banned, including for example alcohol.

3. Refutation by contradictory consequences

The refutation by contradictory consequences is a kind of ad hominem*, used in dialectic:

Peter says “S is P”.
S has the consequence Q: the fact is known and accepted by the opponent.
P and Q are incompatible
So Peter says incompatible things about S.

Example:

Pierre says that power is good.
Yet, everyone agrees that power corrupts (consequence)
Corruption is an evil.
The good is incompatible with the evil; to be good, power should exclude corruption.
Peter says contradictory things.