I once happen to see a Current Reality Tree cluttered with “coulds” and “shoulds”. Conditional or tentative language cannot be used with logic trees and here is why.
Cause-and-effect (sufficiency logic)
The Logical Thinking Process logic trees use either sufficiency or necessity logic. Sufficiency or cause-and-effect relationship states that a cause, if it exists, is sufficient by itself for the effect to happen. Using conditionals like should or could violates the sufficiency principle as it suggests that the cause is not always producing the effect.
If a should or could is found in such a tree, the scrutinizer must raise a “cause insufficiency reservation“. The statement must then be corrected, for example by adding one or more additional cause(s) combining to the first one with a logical AND connector. If this combination is valid, the sufficiency relationship is restored and should or could is removed as the effect is now guaranteed to happen.
If no additional causes can combine to the first one, the cause-and-effect relationship is probably only assumed or false. Anyway no should or could can be left in a logically sound tree.
Using present tense
The entities – the building blocks of the logic trees holding the statements – must be expressed in present tense.
Using present tense is natural in a Current Reality Tree (CRT) as it is the description of the actual situation, the cause-and-effects relationships that exist right now.
The use of present tense in Future Reality Trees (FRT) is highly recommended even so these future situations and the Desirable Effects do not yet exist. Present tense helps to project oneself and the audience into the future and visualize the situation as it were already improved (Scheinkopf, “Thinking for a change, putting the TOC Thinking Processes to use”, p119). Dettmer also recommends to use positive wording (Dettmer, The Logical Thinking Process, p244).
This applies to entities in a CRT, a FRT and in a Prerequisite Tree (PRT) which are verbalized in full sentences.
What about necessity-based logic?
Can necessity logic based tree use conditional/ tentative language?
The Goal Tree (GT), the Evaporating Cloud (EC) and Prerequisite Tree (PRT) are built on necessity logic. They describe the chains of enabling conditions that are required to achieve a goal or an objective. Without the enabling conditions, the objective cannot be attained. Conversely, with the enabling, necessary conditions fulfilled, the objective will not automatically be achieved; additional action is required.
As the Desired Effect is not guaranteed to happen even so all necessary conditions are fulfilled, the use of conditional / tentative language seems legit. Practitioners would not use it though.
First because we need to demonstrate positivity about a desirable change and help the audience to mentally visualize the future where things happen and produce the desired outcome.
Second because we need to give confidence and demonstrate our own trust in the proposed solution. No audience would be thrilled hearing that this solution “may”, “should” or “could” produce the desired result. No decision maker would give his/her go for a change program or a solution implementation which is not certain to produce the expected result.
The use of conditional / tentative language would only raise concern about the feasibility of the proposed solution and appear as a lack of confidence of its promoters.
Tentative language is recommended in academic writing, not at all with logic trees.
Using tentative language is recommended in academic writing and scientific research in order to leave room for alternatives, later corrections, etc. unless there is solid evidence backing up a statement. Therefore the use of verbs like “appear, suggest, indicate,…”, modals “may, might, can, could, will, would” and adverbs like “possibly, probably, likely…” are recommended.
But when building or presenting logic trees, absolute certainty is required in order to demonstrate robustness of the analysis and the confidence in the conclusions. If a logic tree is built on the canonical logic rules (we’ll consider the use of present tense as a canonical logic rule), has been scrutinized and cleared of all reservations, it is robust and tentative language is no option.